Localization and Quantification of Myocardium at Risk by Myocardial Perfusion SPECT During Coronary Artery Occlusion

Introduction and objectives The aim of this study was to analyze the distribution and extent of the myocardium at risk using polar maps obtained with myocardial perfusion SPECT. Myocardial perfusion of territories irrigated by the left anterior descending (LAD), right coronary (RCA) and left circumflex artery (CX) was studied with the help of a technetium-radiolabeled tracer during occlusion of the vessels in the course of percutaneous coronary angioplasty. Patients and method We studied 50 patients (24 LAD, 15 RCA and 11 CX). The 99mTc compound was injected immediately after inflation of the balloon, and the artery was occluded for approximately 90 seconds. Tomographic images were acquired, and polar maps showing the extent of the ischemic region (uptake Results Mean percentage extent of the ischemic territory was 49.8 ± 10.3% (minimum 35%, maximum 67%), for the proximal LAD, 39.8 (8.3%) (minimum 20%, maximum 51%) for the mid LAD, 20.3 (7.6%) (minimum 8.3%, maximum 35%) for the RCA, and 21.3 (10.8%) (minimum 10.2%, maximum 30%) for the CX. Conclusions The contours and extent of the jeopardized myocardial territory found during coronary occlusion allowed us to generate polar maps that illustrated actual coronary risk. The distribution and extent of the areas at risk differed from those in polar maps generated by most current applications used with myocardial perfusion SPECT.