Patent Application
20220175260
The present invention relates to the field of cardiac disease, in particular to the assessment of coronary vessels, in particular to determine the mechanisms and patterns of blockage or restriction to the blood flow through a coronary vessel. The present invention provides diagnostic methods and devices to determine the condition of coronary artery disease, in specific to determine the functional pattern (focal or diffuse) of coronary artery disease.
Physiological assessment of coronary artery disease has been encouraged since the early days of percutaneous coronary interventions.1 In the last two decades, randomized controlled trials have confirmed the clinical benefit of invasive functional assessment to guide clinical decision making about myocardial revascularization in patients with stable coronary artery disease.2, 3 In clinical practice, hemodynamic significance of epicardial coronary stenoses is assessed by means of pressure ratios. Fractional flow reserve (FFR), assessed as the pressure ratio between distal coronary and aortic pressure during pharmacologically-induced hyperaemia, depicts the maximal achievable flow in a coronary vessel.4 FFR has been recommended by the American and European guidelines to determine lesion significance and appropriateness for revascularization.5, 6 Treatment decision-making is based on one FFR value which provides a vessel level metric surrogate of myocardial ischemia.
Pressure losses in the coronary arteries can ensue due to viscous friction and flow separation. The contribution of each of these components are depicted by the Bernoulli equation and Poiseuille Law and are highly dependent on patient-specific coronary geometries. Reduction in luminal area modulated by lesion length diminish pressure distal to epicardial stenosis. Also, lesion features affecting laminar flow conditions contribute to pressure drop.7, 8 Along a normal coronary artery, no pressure loss is found even during maximal microvascular vasodilation9. In contrast, early stage coronary atherosclerosis is often associated with mild epicardial resistance in the coronary arteries before a segmental stenosis is apparent in invasive coronary angiography. This is identifiable by intra coronary pressure measurements and can contribute to the development of myocardial ischemia.10. Conventional coronary angiography has been traditionally used to assess stenosis significance and the spatial pattern of coronary artery disease (i.e. focal or diffuse). Nevertheless, coronary angiography is inaccurate in assessing the functional significance of a coronary stenosis when compared with the FFR.11 Also, intravascular imaging and coronary computed tomography studies have revealed that coronary angiography underestimates the burden and the spatial distribution of coronary atherosclerosis.12 13 Moreover, using intravascular ultrasound, diffuse atherosclerosis is commonly observed in angiographically normal coronary artery reference segments in patients with stable coronary artery disease.14 The relationship between atherosclerosis distribution its repercussion on luminal geometry and epicardial conductance along coronary vessels remains to be elucidated.
The distribution of epicardial conductance can be evaluated using an FFR pullback manoeuvre.4 This technique reveals the contribution of focal and/or diffuse coronary artery disease (CAD) in terms of FFR drop along the coronary vessel.
The evaluation of the pattern of coronary artery disease (i.e. focal or diffuse) is one of the most compelling questions in interventional cardiology and accordingly there is a need for improved devices, systems and diagnostic methods for assessing the pattern of coronary artery disease. It is generally known that coronary vessels with diffuse pattern of coronary artery disease respond poorly to percutaneous coronary intervention with stent implantation. In contrast, vessels with focal disease respond favourably to percutaneous coronary intervention with stent implantation. In particular, there exists a need for diagnostic methods which can guide an interventional cardiologist with a treatment option in the different patterns of coronary artery disease.
According to a first aspect of the invention, there is provided a computer-implemented method for quantifying the patterns of coronary artery functional disease in a coronary vessel from a patient under hyperaemic conditions, comprising the following steps:
According to an embodiment, there is provided a method, wherein the method comprises the further step of:
According to an embodiment, there is provided a method, wherein:
According to an embodiment, there is provided a method, wherein:
According to an embodiment, there is provided a method, wherein the predetermined threshold is equal to a relative pressure drop of 0.0015 per mm of length of the coronary vessel.
According to an embodiment, there is provided a method, wherein the method comprises the steps of:
According to an embodiment, there is provided a method, wherein the method comprises said step of:
According to an embodiment, there is provided a method, wherein the method comprises said step of:
wherein ΔFFRlesion is defined as the difference between FFR values at the proximal and distal edge of the functional disease; ΔFFRvessel as the difference between FFR values between the ostium and the most distal part of the coronary vessel; Length with FFR drop is defined as the sum of contiguous millimeters with FFR drop ≥0.0015; and the total vessel length is the distance between the ostium and the most distant part of the coronary vessel.
According to an embodiment, there is provided a method, wherein, when the value of the FOI:
According to an embodiment, there is provided a method, wherein said set of multiple of relative pressure values were obtained:
According to a second aspect, there is provided a computer device for evaluating coronary artery disease in a patient under hyperaemic conditions, said computer device configured to generate an FFR curve based on a multiple of FFR values, which are relative pressure measurements from pressures obtained at different positions along the total length of the coronary vessel between the ostium and the most distal part of the coronary vessel, relative to the pressure at the ostium of the coronary vessel, and wherein said computer device is further configured to map said multiple of FFR values along the coronary vessel length, and to determine:
According to an embodiment, there is provided a computer device, wherein: said computer device comprises a computer algorithm configured to calculate a functional outcome index (FOI) based on the combination of:
According to an embodiment, there is provided a computer device, wherein said computer device comprises a computer algorithm configured to calculate a functional outcome index (FOI) based on the FFR curve and the correlation of the FFR values over the total length of the vessel, the computer output configured to display an FOI value, such that the FOI value is an expression of at least one of the following functional patterns of coronary artery disease:
According to an embodiment, there is provided a computer device, wherein said computer device comprises a computer algorithm configured to calculate said functional outcome index (FOI) on the data from the FFR curve based on formula:
wherein ΔFFRlesion is defined as the difference between FFR values at the proximal and distal edge of the functional disease; ΔFFRvessel as the difference between FFR values between the ostium and the most distal part of the coronary vessel; Length with FFR drop is defined as the sum of contiguous millimeters with FFR drop ≥0.0015; and the total vessel length is the distance between the ostium and the most distant part of the coronary vessel.
According to an embodiment, there is provided a computer device further configured to co-register the relative pressure measurements with the positions in the coronary vessel. According to a particular embodiment the co-registration of the position in the coronary vessel could be performed by means of angiography, however according to alternative embodiments, the position embodiment could be derived from a measurement and/or registration of the displacement of the pressure wire with respect to the catheter, for example by means of a suitable sensor configured to determine the displacement and or distance by the pressure wire and the at least one sensor thereon with respect to the catheter, such as any suitable position sensor, such as for example a linear position sensor, an opto-electronic displacement sensor, etc. or according to sill further alternative embodiments by means of a suitable visual scale present on the pressure wire, that allows for a manual input of the displacement and/or the relative position of the pressure wire with respect to the catheter, or in other words, how far or over what length the pressure wire and its corresponding at least one sensor are introduced into the vessel with respect to the ostium of the vessel.
According to an embodiment, there is provided a system, wherein the system comprises at least one of the following, in communication with the computer device, and configured to generate the multiple FFR values:
Further embodiments of the system, in which the computer device implements the embodiments of the computer-implemented method according to the first aspect and/or combinations thereof are possible.
According to a further aspect there is provided a method for quantifying the patterns of coronary artery functional disease in a coronary vessel from a patient comprising the following steps:
Further embodiments of the method, in which the method implements the embodiments of the computer-implemented method according to the first aspect and/or combinations thereof are possible.
Further, there is provided, according to a further aspect, a method, further comprising the step of informing an interventional cardiologist with a treatment option for the coronary vessel based on the value of the FOI, wherein:
According to an embodiment we characterized in a systematic manner the physiological patterns of coronary artery disease (CAD) using manual or motorized coronary pressure pullbacks during continuous hyperaemia in patients with stable coronary artery disease. Standardization of the pressure-length relationship of the coronary artery was accomplished by motorising FFR pullbacks which allowed for accurate and reproducible tracings. We developed a new algorithm which calculates the functional outcomes index (FOI). This new parameter is based on the functional impact of anatomical lesions on coronary artery disease. In still other words, the FOI is a continuous metric wherein values approaching “1.0” represent focal physiological coronary artery disease and values close to “0” represent diffuse CAD. The FOI value has therefore a direct impact on the treatment decision for an interventional cardiologist. According to such an embodiment the functional outcome index (FOI) is calculated on the data from the FFR pullback curve based on formula:
wherein ΔFFRlesion is defined as the difference between FFR values at the proximal and distal edge of the functional disease; ΔFFRvessel as the difference between FFR values between the ostium and the most distal part of the coronary vessel; Length with FFR drop is defined as the sum of contiguous millimeters with FFR drop ≥0.0015; and the total vessel length is the distance between the ostium and the most distant part of the coronary vessel. It is clear that in this way the ratio of
varies between 0 and 1 or in other words 0% and 100%. It is further also clear that the extent of the functional disease of the coronary vessel as defined by the ratio
also varies between 0 and 1 or in other words 0% and 100%. It is thus clear that in the formula above both terms of the sum combine to a value that varies between 0 and 2, and that thus a division by 2 can be performed in order to arrive at a value for FOI which varies between 0 and 1 or in other words 0% and 100%.
According to a further aspect there is provided a diagnostic method for quantifying artery disease in a coronary vessel from a patient comprising the following steps:
According to an embodiment, there is provided a diagnostic method, wherein the multiple of FFR values were obtained by a motorized pullback.
According to an embodiment, there is provided a diagnostic method, wherein the multiple of FFR values were obtained by a pressure wire comprising a multiple of built-in pressure sensors.
According to an embodiment, there is provided a diagnostic method, further comprising informing an interventional cardiologist with a treatment option for the coronary vessel based on the value of the FOI, wherein when the value of the FOI is higher than 0.7 indicates the presence of a focal lesion in the coronary vessel.
According to an embodiment, there is provided a diagnostic method, which suggests the interventional cardiologist no intervention or an intervention wherein an intervention comprises an angioplasty, a stent, a pharmaceutical or a combination thereof.
According to a further aspect, there is provided a system for evaluating coronary artery disease in a patient under hyperaemic conditions, comprising
According to an embodiment, there is provided a system, wherein the pressure wire said pressure wire is coupled to a motorized device with a fixed pullback speed.
The present invention will be described with respect to particular embodiments and with reference to certain drawings, but the invention is not limited thereto but only by the claims. Any reference signs in the claims shall not be construed as limiting the scope. The drawings described are only schematic and are non-limiting. In the drawings, the size of some of the elements may be exaggerated and not drawn on scale for illustrative purposes. Where the term “comprising” is used in the present description and claims, it does not exclude other elements or steps. Where an indefinite or definite article is used when referring to a singular noun e.g. “a” or “an”, “the”, this includes a plural of that noun unless something else is specifically stated. Furthermore, the terms first, second, third and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a sequential or chronological order. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein are capable of operation in other sequences than described or illustrated herein. The following terms or definitions are provided solely to aid in the understanding of the invention. Unless specifically defined herein, all terms used herein have the same meaning as they would to one skilled in the art of the present invention. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art (e.g. in molecular biology, interventional cardiology fluid physics, biochemistry, and/or computational biology).
Randomized controlled trials have confirmed the clinical benefit of invasive functional assessment to guide clinical decision making about myocardial revascularization in patients with stable coronary artery disease. Treatment decision is currently based on only one FFR value which provides a vessel level metric surrogate of myocardial ischemia. In the present invention we characterized the physiological patterns of coronary artery disease using manual or motorized coronary pressure pullbacks during continuous hyperaemia in patients with stable coronary artery disease. In our prospective, multicentre study of patients undergoing clinically-indicated coronary angiography, a pullback device, adapted to grip the coronary pressure wire was set at a speed of 1 mm/sec. The pattern of coronary artery disease was adjudicated based on coronary angiography and on the manual or motorized FFR pullback curve as focal, diffuse or as a combination of both mechanisms. Also, a quantitative assessment of the physiological pattern of coronary artery disease was established by computing the functional outcomes index (FOI).
The FOI is a continuous metric, values approaching 1.0 represent focal physiological CAD and value close to 0 diffuse CAD.
Thus, the present invention provides a new diagnostic method which incorporates a new metric, the functional outcome index (FOI). The FOI takes into account the functional impact of anatomical lesions and the extent of physiological disease, and the FOI value differentiates focal from diffuse CAD.
Accordingly, the present invention provides in a first embodiment a method for assessing a treatment option for a lesion present in a coronary vessel during continuous infusion of a hyperemic agent comprising the following steps:
It is clear that the pressure dropped or relative pressure dropped in the suspected lesions, corresponds to the aggregation or sum of pressure drop or relative pressure drop at the location of all the suspected lesions along the coronary vessel. In other words, the pressure drop and/or relative pressure drop between the proximal and distal edge in case of a single, continuous suspected lesion, or, in case of multiple, serial and/or discontinuous suspected lesions the sum or aggregation of the pressure drop and/or relative pressure drops for each lesion between its respective proximal and distal end. Or in other words, it is clear that the relative pressure drop between the proximal and distal edge of the functional disease corresponds to difference between the relative pressure value at the distal end of the functional disease and the relative pressure value at the proximal end of the functional disease. It is further clear that according to particular embodiments the FFR drop of the functional disease, or the FFR drop of the suspected lesions corresponds to the FFR at the distal end of the functional disease or suspected lesions, minus the FFR at the proximal end of the functional disease or suspected lesions. Similarly it is clear that the relative pressure drop between the ostium and the most distal end of the coronary vessel, corresponds to the difference, delta or gradient between the most distal relative pressure measurement of the vessel and the ostial relative pressure measurement of the vessel. According to particular embodiments this thus means the difference between the FFR at the distal end of the vessel and the FFR at the ostium of the vessel.
In yet another embodiment the invention provides a method for assessing a treatment option for a lesion present in a coronary vessel during and/or after infusion, such as for example continuous infusion or any other suitable type of infusion, of a hyperemic agent comprising the following steps:
It is thus clear that according to an embodiment, when the FOI is lower than 0.4, this indicates the functional pattern of a diffuse coronary artery disease. It is however clear that alternative embodiments are possible in which, for example a functional pattern of a diffuse coronary artery disease is indicated when the FOI is lower than a suitable maximum threshold, such as for example lower than 0.3, lower than 0.2, or lower than 0.15
The wording ‘the pressure drop in the full vessel’ means the pressure difference obtained between the pressure measured at the ostium of the coronary vessel and the pressure obtained at the most distal part of the coronary vessel.
In yet another embodiment the invention provides a method for assessing a treatment option for a lesion present in a coronary vessel under hyperaemic conditions, for example upon a bolus injection or during continuous infusion of a hyperemic agent, comprising the following steps:
It is thus clear that the length of the vessel, also referred to as the total vessel length, can be determined by determining the distance between and/or the difference between the positions mapped to the pressure values associated with the ostium and the most distal part of the coronary vessel.
In yet another embodiment the invention provides a diagnostic method for quantifying artery disease in a coronary vessel from a patient comprising the following steps:
In the present invention the terms a ‘guide wire comprising at least one pressure sensor’ or a ‘pressure wire’ are equivalent.
In a specific embodiment the fractional flow reserve (FFR) curve is obtained by a manual or motorized pullback device which device is attached to the pressure wire.
In yet another particular embodiment there is no need for a motorized pullback device but instead the FFR curve is obtained by a pressure wire comprise a multiple of built-in pressure sensor. Particularly, the FOI value does not change when the pullback is carried out manually or with the aid of a motorized device. In particular embodiments the diagnostic methods of the invention provide a treatment suggestion to an interventional cardiologist based on the value of the FOI, wherein when the value of the FOI is higher than 0.7, higher than 0.8 or higher than 0.9 indicates the presence of a focal lesion in the coronary vessel and benefits from percutaneous coronary intervention with stent implantation. In particular embodiments the diagnostic methods of the invention provide a treatment suggestion to an interventional cardiologist based on the value of the FOI, wherein when the value of the FOI is preferably lower than 0.4, lower than 0.3 or lower than 0.2, lower than 0.15, this indicates the presence of a diffuse lesion in the coronary vessel and does not benefit from percutaneous coronary intervention with stent implantation. It has further been found that a treatment suggestion to an interventional cardiologist based on the value of the FOI, wherein when the value of the FOI is higher than 0.4 and lower than 0.7, such as for example in the range of 0.5 to 0.7 which indicates the presence of a combination of focal and diffuse lesions in the coronary vessel, can be made, that there might still be a benefit from percutaneous coronary intervention with stent implantation. However, with an FOI lower than 0.4 there will be no benefit from does not benefit from a treatment with percutaneous coronary intervention with stent implantation.
In a particular embodiment, the catheter is configured to obtain diagnostic information about the coronary vessel. In this respect, the catheter can include one or more sensors, transducers, and/or other monitoring elements configured to obtain the diagnostic information about the vessel. The diagnostic information includes one or more of pressure, flow (velocity), images (including images obtained using ultrasound (e.g. IVUS), optical coherence tomography (OCT), thermal, and/or other imaging techniques), temperature, and/or combinations thereof. These one or more sensors, transducers, and/or other monitoring elements are positioned less than 30 cm, less than 10 cm, less than 5 cm, less than 3 cm, less than 2 cm, and/or less than 1 cm from a distal tip of the catheter in some instances. In some instances, at least one of the one or more sensors, transducers, and/or other monitoring elements is positioned at the distal tip of the catheter. In another particular embodiment the catheter comprises at least one element configured to monitor Pressure within the coronary vessel. The pressure monitoring element can take the form a piezo-resistive pressure sensor, a piezo-electric pressure sensor, a capacitive pressure sensor, an electromagnetic pressure sensor, an optical pressure sensor, and/or combinations thereof. In some instances, one or more features of the pressure monitoring element are implemented as a solid-state component manufactured using semiconductor and/or other suitable manufacturing techniques.
In yet another embodiment the catheter comprises a pressure wire (or a guide wire). Examples of commercially available guide wire products that include suitable pressure monitoring elements include, without limitation, the Prime Wire PRESTIGE® pressure guide wire, the Prime Wire® pressure guide wire, and the ComboWire® XT pressure and flow guide wire, each available from Volcano Corporation, as well as the Pressure Wire™ Certus guide wire and the Pressure Wire™ Aeris guide wire, each available from St. Jude Medical, Inc or COMET™ FFR pressure guidewire from Boston Scientific. The pressure wire is also configured to obtain diagnostic information about the coronary vessel. In some instances, the pressure wire is configured to obtain the same diagnostic information as the catheter. In other instances, the pressure wire is configured to obtain different diagnostic information than the catheter, which may include additional diagnostic information, less diagnostic information, and/or alternative diagnostic information. The diagnostic information obtained by the pressure wire includes one or more of pressure, flow (velocity), images (including images obtained using ultrasound (e.g. IVUS), OCT, thermal, and/or other imaging techniques), temperature, and/or combinations thereof.
Similar to the catheter the pressure wire also includes at least one element configured to monitor pressure within the vessel. The pressure monitoring element can take the form a piezo-resistive pressure sensor, a piezo-electric pressure sensor, a capacitive pressure sensor, an electromagnetic pressure sensor, an optical pressure sensor, and/or combinations thereof. In some instances, one or more features of the pressure monitoring element are implemented as a solid-state component manufactured using semiconductor and/or other suitable manufacturing techniques. In a particular embodiment the pressure wire can comprise multiple pressure sensors, e.g. at least 10, at least 20, at least 30, at least 40, at least 50, or more pressure sensors. It is clear that according to such embodiments of the pressure wire, the multiple pressure sensors are provided at different positions along the length of the pressure wire, and thus configured to, even when stationary, after being introduced into the coronary vessel up to the distal end of the coronary vessel, determine a coronary vessel, or in other words at different positions between the ostium and the distal end of the coronary vessel.
In a particular embodiment the pressure wire is configured to monitor pressure within the vessel while being moved through the lumen of the vessel. In some instances, the pressure wire is configured to be moved through the lumen of the vessel and across the stenosis present in the vessel. In that regard, the pressure wire is positioned distal of the stenosis and moved proximally (i.e. pulled back) across the stenosis to a position proximal of the stenosis in some instances. Movement of the pressure wire can be controlled manually by medical personnel (e.g. hand of a surgeon) in some embodiments. In other preferred embodiments, movement of the pressure wire is controlled automatically by a movement control device (e.g. a pullback device, such as the Trak Back® II or Volcano R-100 Device available from Volcano Corporation). In that regard, the movement control device controls the movement of the pressure wire at a selectable and known speed (e.g. 5.0 mm/s, 2.0 mm/s, 1.0 mm/s, 0.5 mm/s, etc.) in some instances. Movement of the pressure wire through the vessel is continuous for each pullback, in some instances. In other instances, the pressure wire is moved step-wise through the vessel (i.e. repeatedly moved a fixed amount of distance and/or a fixed amount of time).
In yet another embodiment the invention provides a system for evaluating coronary artery disease in a patient under hyperaemic conditions, comprising
In yet another embodiment the invention provides a system for evaluating coronary artery disease in a patient under hyperaemic conditions, comprising
In the present invention a “system” is equivalent to a “device” or an “apparatus”.
A computing device is generally representative of any device suitable for performing the processing and analysis techniques discussed within the present disclosure. In some embodiments, the computing device includes a processor, random access memory, and a storage medium. In that regard, some particular instances the computing device is programmed to execute steps associated with the data acquisition and analysis described herein. Accordingly, it is understood that any steps related to data acquisition, data processing, calculation of the FOI, instrument control, and/or other processing or control aspects of the present disclosure may be implemented by the computing device using corresponding instructions stored on or in a non-transitory computer readable medium accessible by the computing device. In some instances, the computing device is a console device. In some instances, the computing device is portable (e.g. handheld, on a rolling cart, etc.). Further, it is understood that in some instances the computing device comprises a plurality of computing devices. In that regard it is particularly understood that the different processing and/or control aspects of the present disclosure may be implemented separately or within predefined groupings using a plurality of computing devices. Any divisions and/or combinations of the processing and/or control aspects described herein across multiple computing devices are within the scope of the present disclosure.
It is understood that any communication pathway between the catheter and the computing device may be utilized, including physical connections (including electrical, optical, and/or fluid connections), wireless connections, and/or combinations thereof. In that regard, it is understood that the connection IS wireless in some instances. In some instances, the connection a communication link over a network (e.g. intranet, internet, telecommunications network, and/or other network). In that regard, it is understood that the computing device is positioned remote from an operating area where the catheter is being used in some instances. Having the connection include a connection over a network can facilitate communication between the catheter and the remote computing device regardless of whether the computing device is in an adjacent room, an adjacent building, or in a different state/country. Further, it is understood that the communication pathway between the catheter and the computing device is a secure connection in some instances. Further or more portions of the communication pathway between the catheter and the computing device is encrypted.
It is also understood that the FOI value obtained regarding characteristics of the coronary artery disease (predicted to be diffuse, intermediate or focal lesion) as indicated by the FOI value can be compared with or considered in addition to other representations of the lesion or stenosis and/or the vessel (e.g. IVUS (including virtual histology), OCT ICE, Thermal, Infrared, flow, Doppler flow, and/or other vessel data-gathering modalities) to provide a more complete and/or accurate understanding of the vessel characteristics. For example, in some instances the information regarding characteristics of the lesion or stenosis and/or the vessel as indicated by the FOI value are utilized to confirm information calculated or determined using one or more other vessel data-gathering modalities.
It is to be understood that although particular embodiments, specific configurations as well as materials and/or molecules, have been discussed herein for cells and methods according to the present invention, various changes or modifications in form and detail may be made without departing from the scope and spirit of this invention. The following examples are provided to better illustrate particular embodiments, and they should not be considered limiting the application. The application is limited only by the claims.
From November 2017 to January 2019, 111 patients with 158 vessels were included in two European centers. In 100 vessels (79 patients) motorized FFR pullback analysis was feasible (
Anatomically and functional CAD were observed in 85 vessels. In 15 cases, pullback curves were assessed as having no physiological disease despite the presence of anatomical stenosis and were excluded from this analysis. Using coronary angiography alone, 63% of the vessel were classified as having focal CAD, 26% as diffuse disease and 11% as a combination of focal and diffuse CAD. The inter-observer agreement on the pattern of CAD based on conventional angiography alone was moderate (Fleiss' Kappa coefficient 0.45; 95% CI 0.29 to 0.61). After the evaluation of the FFR pullback curve, 53% of the vessels were identified as focal disease, 20% as diffuse disease and 27% showed a combined pattern of pressure drop. The inter-observer agreement based on the physiological CAD pattern was substantial (Fleiss' Kappa 0.76; CI 0.67 to 0.87). Of the patients identified with anatomical focal disease, 26% was reclassified to a diffuse or combined CAD pattern whereas 13% of anatomical diffuse disease was reclassified as focal CAD (
The mean FFRlesion 61.7±25% whereas the mean percent vessel length with physiological disease was 59.8±21%. The % FFRlesion and length with physiological disease stratified by the physiological CAD pattern is shown in Table 2. The correlation between delta FFR pressure drop and percent diameter stenosis was weak (r=0.21, p=0.028;
A total of 25 vessels with anatomically defined serial lesions were present in this cohort. By visually assessment of the FFR pullback curve, 40% of vessels with serial lesions were adjudicated as two focal drops, 52% as a combination of focal and diffuse drop and 8% as diffuse CAD. When the contribution of the serial lesions was combined the % FFRlesion was 70.2±20%. The % FFRlesion in the proximal lesion was 35.0±20% and 34.9±19% for the distal lesion (p=0.99). Percent vessel length without physiological disease was 46±17%. The mean FOI was 0.58±0.15 (range 0.30 to 0.95). A sensitivity analysis including only vessel with distal FFR<0.80 revealed a similar distribution of the physiological patterns of coronary artery disease and FOI.
The main findings to come to the present invention can be summarized as: 1) coronary angiography was inaccurate to assess the pattern and distribution of CAD; 2) using motorized FFR pullbacks 34% of the vessel disease patterns were reclassified (i.e. focal, diffuse or combined) as compared to conventional angiography; 3) the inclusion of the functional component increased the interobserver agreement concerning the identification of the disease pattern; 4) a new computer algorithm was developed to calculate the FOI. The FOI is based on the functional impact of anatomical lesions and the extent of physiological disease discriminated focal and diffuse CAD using a quantitative metric.
The present invention provides a characterization of the physiological patterns of CAD by assessing the distribution of epicardial coronary resistance under hyperaemic conditions in patients with stable coronary artery disease. Using motorized FFR pullbacks, novel insights into the mechanisms of pressure losses in patients with stable CAD are described. Moreover, the co-registration with coronary angiography allowed us to assess the relationship between anatomical and functional findings at the lesion level confirming a moderate correlation between diameter stenosis and pressure gradient. Three physiological CAD patterns were observed, namely, focal, diffuse or a combination of both mechanisms.
The discrepancy between anatomical and physiological significance of coronary disease has been widely recognized.11 moreover, there is no consensus regarding the definition of diffuse CAD. Several authors have proposed different descriptions of diffuse CAD based extent of atherosclerosis, vessel diameter, number of lesions and appearance of distal run-off.9, 16, 17 The present analysis extends our knowledge to the contribution epicardial lesions to overall pressure gradients. In this study, 62% of the vessel FFR drop was related to angiographically visible stenosis; in other words, almost 40% of the FFR drop was not related to angiographic narrowing. Moreover, physiological disease was observed 60% of the vessel length whereas percent lesion length 25% of the vessel length. This analysis reassembles the intravascular ultrasound observations of diffuse coronary atherosclerosis with a physiological repercussion in terms of pressure losses along the coronary vessels. Moreover, these findings could be extrapolated to recent randomized clinical trials in the field of coronary physiology. In the present study, the mean distal FFR was 0.83±0.09 that is comparable with the ones observed in Define Flair (0.83±0.09) and SWEDEHEART (0.82±0.10).18, 19 One fourth of the vessels assessed as focal CAD with conventional angiography showed also diffuse physiological disease whereas one out of ten vessels with an anatomical diffuse disease was reclassified as focal CAD using a motorized FFR pullback. The evaluation of the FFR pullback curve reclassified 34% of the vessel CAD patterns. Moreover, the use of coronary physiology increased the inter-observer reproducibility concerning the CAD pattern. Nonetheless, it should be recognized that using a visual evaluation of the FFR pullback curve a discrepant assessment on the CAD pattern was observed in 19% of the vessel.
The distribution of coronary atherosclerosis (e.g. focal and diffuse) has been shown to influence clinical-decision making about the revascularization strategy. Patients with anatomically diffuse CAD are often managed conservatively with optimal medical therapy or referred to coronary artery bypass grafting.20 Interestingly, diffuse disease has been shown to carry an adverse prognosis even in patients undergoing surgery. Diffuse physiological disease in the LAD has been associated with higher rate of left internal mammary artery graft occlusion as compared with focal disease.17 Moreover, despite the clinical benefit observed PCI in patients with distal vessel FFR<0.80, one third of the patients undergoing PCI remain with a suboptimal FFR post-PCI which is associated with major adverse cardiac events.21 3 Focal percutaneous based therapies are likely able to restore coronary physiology and relieve ischemia in cases of focal physiological CAD. However, the clinical benefit of PCI in cases of diffuse CAD can be questioned.21 22In patients managed medically, the assessment of lesion-related gradients might also aid in lesion-based risk stratification; high delta lesions FFR gradients (i.e. >0.06) has been identified as a hemodynamic predictor of plaque rupture and acute coronary syndromes.23 On top of contemporary risk stratification using clinical characteristics, luminal and atherosclerotic plaque components, and the presence of ischemia, determining FFR lesion gradients and the physiological pattern of CAD may further refine lesion-based risk stratification. Furthermore, an individualized approach based on the physiological disease at the vessel and lesion level has the potential to improve clinical decision-making and outcomes.
In the present invention, a new physiological metric to objectivize the pattern of CAD was developed. The FOI epitomise the physiological pattern of CAD as focal, diffuse or combined. Rather than trichotomizing the data to define the pattern of CAD, the FOI should be interpreted as a continuous metric. The higher the FOI the more focal CAD and higher the potential gain in epicardial conductance with PCI. The availability of a quantitative metric to characterize CAD patterns under hyperaemic conditions has enabled us to design a clinical trial to investigate the effectiveness of PCI versus optimal medical therapy stratified by the physiological pattern of CAD. This will further personalize treatment strategies in patient with CAD based on coronary physiology.
Some authors have defined the presence of serial lesions as diffuse CAD. In the current cohort, serial lesions were found in 29% of the vessels. Visually the FFR pullback curve depicted two focal drops in Visually the FFR pullback curve depicted two focal drops in 40%, one focal combined with a diffuse drop in 52% and diffuse disease (no focal FFR drops) in 8%. The FOI ranged from 0.30 to 0.95 depicting the variable physiological repercussion of serial lesions. Physiological interdependency in the coronary tree, the so-called lesion cross-talked, has been described under hyperaemic conditions.24 We observed that the functional contribution of each lesion in terms of percent delta FFR was similar for proximal and distal lesions. No differences were found concerning percent diameter stenosis or % FFRlesion between the proximal and distal lesion.
This finding is likely consequence of the intermediate angiographic disease (mean percent diameter stenosis 45.9±14.2%) observed in this population which might be insufficient to reduce coronary flow and ameliorate pressure gradients in the distal lesion.25 26 27 In cases of serial lesions, the true FFR gradient can be unmasked by the removal of one lesion and reassessment of FFR. Kim et al. have found that treating the lesion with the greatest delta FFR and reassessing the functional component of the vessel to determine whether further treatment is required is a safe strategy.28 Also, traditional statistics and machine learning methods have been developed to predict functional outcomes in term of FFR in serial lesions.
The adoption of coronary physiology in clinical practice continues to increase after evidence of clinical benefit compared to anatomical guidance and medical therapy, and the development of non-hyperaemic pressure ratios.29 As the field move forward, refinements in invasive techniques have the potential further improve clinical decision-making and patient selection for revascularization. The characterization of the pattern of coronary artery disease is a necessary step in this direction aiming at predicting which patient benefit the most from PCI, CABG or medical therapy based on the distribution of epicardial resistance. Prediction of functional outcomes after PCI is an important topic and a matter of intense research with non-invasive and invasive methods.30 Angiography-derived FFR and FFR derived from CT angiography have an inherent advantage given the possibility to provide an FFR value at any point of the coronary tree and therefore characterizing the CAD pattern.31 32 It is thus clear that according to such an embodiment, the FFR values at different positions along the length of a coronary vessel could be generated by and/or CT Angiography-derived FFR values acquired from a device configured to provide Angiography-derived FFR values or along the length of the coronary vessel, and/or at any desired point of the coronary tree. These tools will have to demonstrate clinical benefit to be adopted in clinical practice as integral part of the physiological assessment of CAD, refining selection and ultimately improving clinical outcomes of patients with stable coronary artery disease.
Coronary angiography was inaccurate to assess the patterns of CAD. The inclusion of the functional component reclassified 34% of the vessel disease patterns (i.e. focal, diffuse or combined). A new metric, the FOI, based on the functional impact of anatomical lesions and the extent of physiological disease discriminated focal from diffuse CAD has been developed.
Prospective, multicentre study of patients undergoing clinically-indicated coronary angiography. Fractional flow reserve evaluation was recommended in patients with intermediate coronary lesions defined as visual diameter stenosis between 30% and 70%. A motorized FFR pullback was performed at in all patients. Patients presenting with acute coronary syndromes, previous coronary artery bypass grafting, significant valvular disease, severe obstructive pulmonary disease or asthma bronchial, coronary ostial lesions, with severe tortuosity or severe calcification were excluded. The study was approved by the investigational review board or ethics committee at each participating center.
FFR measurements were performed following the recommendations of the Standardization of Fractional Flow Reserve Measurements document.15 Pressure wire was positioned at least 20 mm distal to the most distal coronary stenosis in vessels more than 2 mm of diameter by visual estimation. Pressure-wire position was recorded using contrast injection. The RadiAnalyzer Xpress (St Jude Medical, Mineapolis, USA) and QUANTIEN Integrated FFR System (Abbott Vascular, Illinois, USA) were used to measure invasive coronary pressures. Following intra-coronary nitrates administration, a continuous intra-venous adenosine infusion was given at a dose of 140 μg/kg/h via a peripheral or central vein to obtain a steady-state hyperaemia for at least 2 minutes. A pullback device (Volcano R 100, San Diego Calif., USA), adapted to grip the coronary pressure wire (PressureWire X, St Jude Medical, Mineapolis, USA), was set at a speed of 1 mm/sec to pullback the pressure-wire until the tip of the guiding catheter during continued pressure recording. The maximal pullback length was 13 cm per vessel. If FFR drift (>0.03) was observed, the FFR measurement was repeated.
An FFR value was extracted from the pressure tracing every 10 microns. FFR was defined as the ratio of the moving average of the proximal and distal coronary pressures. Pressure tracings were examined to evaluate quality, curve artefacts and hyperemia stability (Supplementary appendix
Where ΔFFRlesion is defined as the difference between FFR values at the proximal and distal lesion edge of the lesion; ΔFFRvessel as the difference between FFR values between the ostium of the vessel and the most distal FFR measurement, and length with FFR drop defined as the sum of contiguous millimeters with FFR drop ≥0.0015. The FOI is a continuous metric, values approaching 1.0 represent focal physiological coronary artery disease and value close to 0 diffuse coronary artery disease. In cases with serial lesions, the physiological contribution of each lesion was added to calculate ΔFFRlesion. The calculation was performed using an automated and a proprietary algorithm based on the motorized FFR curve.
It is clear that other suitable values for the threshold could be possible for determining the length with FFR drop then the specific value of 0.0015, in which for example the length with FFR drop is defined as the sum of contiguous millimeters with FFR drop≥said suitable threshold. Or in other words, the length of the functional disease, corresponds to the sum of the length of segments of the coronary vessel with relative pressure drops that are larger than or equal to such a predetermined threshold, of for example a relative pressure drop of 0.0015 per mm of length of the coronary vessel, or any other suitable threshold value.
Coronary angiographies were centrally collected and analyzed by an independent core laboratory. The anatomical pattern of coronary artery disease was adjudicated by visual inspection of the target vessel as focal, diffuse or as a combination of both mechanisms. Serial lesions were defined as the presence of two or more narrowings with visual diameter stenosis greater than 50% separated at least by three times the reference vessel diameter.16 Lesion length was detected by an automated quantitative coronary angiography (QCA) software. Vessel length was defined from the vessel ostium until the position of the pressure wire sensor. Manual correction QCA tracing was recorded. Quantitative coronary angiography analyses were performed with CAAS Workstation 8.1 (Pie Medical Imaging, Maastricht, The Netherlands). Co-registration of coronary angiographies and FFR pullbacks was performed off-line using anatomical landmarks recorded during imaging acquisition.
Continuous variables with normal distribution are presented as mean plus/minus standard deviation and non-normally distributed variables as median [interquartile range]. Categorical variables as presented as percentages. Agreement on CAD patterns and between observers was assessed using Fleiss' Kappa. Analysis of variance (ANOVA) was used to compared quantitative variables. Correlation between variables was assess by the Pearson moment coefficient. All analyses were performed in R (R Foundation for Statistical Computing, Vienna, Austria) and graphs created with Data Graph 4.3 software (Visual Data Tool Inc).
| Number | Date | Country | Kind |
|---|---|---|---|
| 1905335.4 | Apr 2019 | GB | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2020/060642 | 4/16/2020 | WO | 00 |
