Índice de resistencia microcirculatoria y obstrucción microvascular en la resonancia magnética cardiaca tras un IAMCEST / Functional angiography-derived index of microcirculatory resistance validated with microvascular obstruction in cardiac magnetic resonance after STEMI

Introducción y objetivos El índice de resistencia microcirculatoria (IRM) medido tras una angioplastia primaria (ICPp) por infarto agudo de miocardio con elevación del segmento ST (IAMCEST) se asocia con la aparición de obstrucción microvascular (OMV) y eventos clínicos adversos. Para evaluar la OMV tras una ICPp exitosa por IAMCEST sin guías de presión ni administración de agentes hiperémicos, variables que parecen limitar la adopción del IRM en el laboratorio de hemodinámica, se investiga la viabilidad y la utilidad de la medición del IRM mediante resonancia magnética cardiaca (RMC) (angio-IRM). Métodos El estudio incluyó a 285 pacientes con IAMCEST sometidos a ICPp y RMC. Con un programa informático comercial, se calculó el angio-IRM del vaso culpable tras la ICPp exitosa. Se evaluaron la OMV, el tamaño del infarto y el índice de rescate miocárdico medidos una mediana de 3 [rango intercuartílico, 3-5] días después de la ICPp. Resultados De la población total, 154 pacientes (54,0%) mostraron valores de angio-IRM elevados (> 40 U) en el vaso culpable. La OMV fue significativamente más frecuente en los pacientes con angio-IRM> 40 U que en aquellos con angio-IRM ≤ 40 U (el 88,3 frente al 32,1%; p <0,001). El tamaño del infarto, la extensión de la OMV y el área en riesgo fueron significativamente mayores en los pacientes con angio-IRM> 40 U que con angio-IRM ≤ 40 U (p <0,001 para todas las comparaciones). El angio-IRM mostró una capacidad de discriminación de OMV significativamente mayor que el grado de flujo TIMI o de blush miocárdico (área bajo la curva, 0,821, 0,504 y 0,496 respectivamente; p <0,001). Conclusiones El angio-IRM se asoció significativamente con el tamaño del infarto, la extensión de la OMV y el área en riesgo. Cifras altas del angio-IRM (> 40 U) tras una ICPp por IAMCEST fueron muy predictivas de OMV en la RMC (AU)

Introduction and objectives The index of microcirculatory resistance (IMR) measured after primary percutaneous coronary intervention (PCI) for ST-segment elevation myocardial infarction (STEMI) is associated with microvascular obstruction (MVO) and adverse clinical events. To evaluate MVO after successful primary PCI for STEMI without pressure wires or hyperemic agents, we investigated the feasibility and usefulness of functional angiography-derived IMR (angio-IMR). Methods The current study included a total of 285 STEMI patients who underwent primary PCI and cardiac magnetic resonance (CMR). Angio-IMR of the culprit vessel after successful primary PCI was calculated using commercial software. MVO, infarct size, and myocardial salvage index were assessed using CMR, which was obtained a median of 3.0 days [interquartile range, 3.0-5.0] after primary PCI. Results Among the total population, 154 patients (54.0%) showed elevated angio-IMR (> 40 U) in the culprit vessel. MVO was significantly more prevalent in patients with angio-IMR> 40 U than in those with angio-IMR ≤ 40 U (88.3% vs 32.1%, P <.001). Infarct size, extent of MVO, and area at risk were significantly larger in patients with angio-IMR> 40 U than in those with angio-IMR ≤ 40 U (P <.001 for all). Angio-IMR showed a significantly higher discriminatory ability for the presence of MVO than thrombolysis in myocardial infarction flow grade or myocardial blush grade (area under the curve: 0.821, 0.504, and 0.496, respectively, P <.001). Conclusions Angio-IMR was significantly associated with CMR-derived infarct size, extent of MVO, and area at risk. An elevated angio-IMR (> 40 U) after primary PCI for STEMI was highly predictive of the presence of MVO in CMR (AU)

Association of Quantitative Flow Ratio with Lesion Severity and Its Ability to Discriminate Myocardial Ischemia

Background and Objectives@#Quantitative flow ratio (QFR) is an angiography-based technique for functional assessment of coronary artery stenosis. This study investigated the response of QFR to different degree of stenosis severity and its ability to predict the positron emission tomography (PET)-defined myocardial ischemia. @*Methods@#From 109 patients with 185 vessels who underwent both 13 N-ammonia PET and invasive physiological measurement, we compared QFR, fractional flow reserve (FFR) and instantaneous wave-free ratio (iFR) for the responses to the different degree of anatomical (percent diameter stenosis [%DS]) and hemodynamic (relative flow reserve [RFR], coronary flow reserve, hyperemic stenosis resistance, and stress myocardial flow) stenosis severity and diagnostic performance against PET-derived parameters. @*Results@#QFR, FFR, and iFR showed similar responses to both anatomic and hemodynamic stenosis severity. Regarding RFR, the diagnostic accuracy of QFR was lower than FFR (76.2% vs. 83.2%, p=0.021) and iFR (76.2% vs. 84.3%, p=0.031). For coronary flow capacity (CFC), QFR showed a lower accuracy than iFR (74.1% vs. 82%, p=0.031) and lower discriminant function than FFR (area under curve: 0.74 vs. 0.79, p=0.044). Discordance between QFR and FFR or iFR was shown in 14.6% of cases and was driven by the difference in %DS and heterogeneous distribution of PET-derived RFR and stress myocardial blood flow. @*Conclusions@#QFR demonstrated a similar response to different anatomic and hemodynamic stenosis severity as FFR or iFR. However, its diagnostic performance was inferior to FFR and iFR when PET-derived RFR and CFC were used as a reference.

Association of Quantitative Flow Ratio with Lesion Severity and Its Ability to Discriminate Myocardial Ischemia

Background and Objectives@#Quantitative flow ratio (QFR) is an angiography-based technique for functional assessment of coronary artery stenosis. This study investigated the response of QFR to different degree of stenosis severity and its ability to predict the positron emission tomography (PET)-defined myocardial ischemia. @*Methods@#From 109 patients with 185 vessels who underwent both 13 N-ammonia PET and invasive physiological measurement, we compared QFR, fractional flow reserve (FFR) and instantaneous wave-free ratio (iFR) for the responses to the different degree of anatomical (percent diameter stenosis [%DS]) and hemodynamic (relative flow reserve [RFR], coronary flow reserve, hyperemic stenosis resistance, and stress myocardial flow) stenosis severity and diagnostic performance against PET-derived parameters. @*Results@#QFR, FFR, and iFR showed similar responses to both anatomic and hemodynamic stenosis severity. Regarding RFR, the diagnostic accuracy of QFR was lower than FFR (76.2% vs. 83.2%, p=0.021) and iFR (76.2% vs. 84.3%, p=0.031). For coronary flow capacity (CFC), QFR showed a lower accuracy than iFR (74.1% vs. 82%, p=0.031) and lower discriminant function than FFR (area under curve: 0.74 vs. 0.79, p=0.044). Discordance between QFR and FFR or iFR was shown in 14.6% of cases and was driven by the difference in %DS and heterogeneous distribution of PET-derived RFR and stress myocardial blood flow. @*Conclusions@#QFR demonstrated a similar response to different anatomic and hemodynamic stenosis severity as FFR or iFR. However, its diagnostic performance was inferior to FFR and iFR when PET-derived RFR and CFC were used as a reference.