Regional, Artery-Specific Thresholds of Quantitative Myocardial Perfusion by PET Associated with Reduced Myocardial Infarction and Death After Revascularization in Stable Coronary Artery Disease

Abstract

Since randomized coronary revascularization trials in stable CAD have shown no reduced MI or mortality, the threshold of quantitative myocardial perfusion severity was analyzed for association with reduced death, MI or stroke after revascularization within 90 days after PET. In a prospective long-term cohort of stable CAD, regional, artery specific, quantitative myocardial perfusion by positron emission tomography (PET), coronary revascularization within 90 days after PET and all cause death, myocardial infarction and stroke (DMS) at 9 years follow-up, mean 3.0 ± 2.3 years, were analyzed by multivariate Cox regression models and propensity analysis. For 3774 sequential rest-stress PET scans, regional, artery specific, severely reduced Coronary Flow Capacity (CFC) (CFR ≤ 1.27 and stress perfusion ≤ 0.83 cc/min/g) associated with 60% increased hazard ratio for major adverse cardiovascular events (MACE) and 30% increased hazard of DMS that was significantly reduced by 54% associated with revascularization within 90 days after PET ( = 0.0369), compared to moderate or mild CFC, CFR, other PET metrics or medical treatment alone. Depending on severity threshold for statistical certainty, up to 19% of this clinical cohort had CFC severity associated with reduced DMS after revascularization. Coronary Flow Capacity by PET provides objective, regional, artery specific, size-severity physiologic quantification of CAD severity associated with high risk of death, MI and stroke that is significantly reduced after revascularization within 90 days after PET, an association not seen for moderate to mild perfusion abnormalities or medical treatment alone.

Class 1C antiarrhythmic drugs in atrial fibrillation and coronary artery disease

“…A relative perfusion abnormality indicating overt CAD was defined as a contiguous defect in greater than 10% of the left ventricle (LV) myocardium with activity less than 60% of maximum at rest, or a contiguous defect in greater than 5% of LV myocardium with activity less than 60% of maximum at stress. The occult CAD was defined as the absence of evidence of overt CAD but with the presence of reduced CFC involving ≥50% of the myocardium 6,7 …”

“…Positron emission tomography (PET) can quantify coronary flow capacity (CFC), which is a novel metric defined by the integration of stress myocardial blood flow (sMBF) and coronary flow reserve into a framework of physiologic severity 6 . Mild reduction in CFC dependably identifies myocardial regions supplied by vessels with CAD but without clinical evidence of ischemia or infarction 7–9 . Thus, PET‐based assessment of coronary flow is able to detect patients who have the presence of CAD that may not be clinically evident otherwise.…”

Pitfalls in quantitative myocardial PET perfusion II: Arterial input function

“…Positron emission tomography (PET) quantifies regional absolute myocardial perfusion in ccÁmin -1 Ág -1 , coronary flow reserve (CFR) and their combination as coronary flow capacity (CFC) associated with reduced mortality after revascularization compared to medical treatment 1 and differentiates focal, diffuse, and small vessel disease. 2 The arterial input function is widely recognized as essential for quantitative myocardial perfusion 3 with an extensive literature that, however, does not resolve several issues for Rb-82 imaging.…”

“…4 Secondly, the simple or retention model (i) is highly reproducible ±10% on test/retest measurement in the same patient within minutes, 6 (ii) has a well-documented threshold severity for stress induced angina or ST depression 9,11 , and (iii) predicts high risk of death or myocardial infarction 1,2 that is significantly reduced by revascularization. 1 However, sensitivity analysis for effects of variable arterial input on severity for guiding interventions needs objective definition.…”

MPI in the era of CZT cameras: Absolute numbers are still better than relative figures

“…17 In addition, the prognostic value of absolute MBF analysis in patients with IHD has been also accumulating, and recent reports have demonstrated how a relatively preserved coronary flow capacity associates with a favorable prognosis even in the presence of extensive CAD, while the presence of a more compromised absolute myocardial perfusion confers a dismal outcome, individuating patients that would benefit from aggressive therapeutic approaches (i.e., surgical coronary revascularization). 18 Finally, the absolute quantification of myocardial perfusion has a capital role in the evaluation of patients with non-obstructed coronary arteries, in whom only MBF assessment may unmask the presence of functional alterations of coronary circulation (i.e., endothelial or microvascular dysfunction due to cardiovascular risk factors). 19 However, the limited availability of cardiac PET scanners and the intrinsic technical complexity of the methodology have prevented the diffusion of absolute MBF evaluation in daily clinical practice.…”