Segmental comparison between coronary angiography and positron emission tomography reveals low predictive value of epicardial flow for viability.

Abstract

The functional significance of the anterograde and retrograde filling of coronaries on angiography is controversial. Eighteen patients with 27 severe lesions (> 85% diameter stenosis) after previous extensive myocardial infarction were selected. The left ventricle was divided into 33 segments for regional comparison of epicardial flow (as assessed by angiography) and tissue perfusion as well as metabolism (as measured by 13NH3- and 18FDG-PET). Viability was defined as normal perfusion (> 80% relative of maximum 13NH3 activity) or mismatch defect (> 1.2 metabolism/flow ratio). A method has been developed to register the 'lesion predicted region', determined on the basis of angiography, in the same polar map as derived from the positron emission tomography data. Distal to the lesion, the anterograde epicardial flow was evaluated by Thrombolysis in Myocardial Infarction (TIMI) criteria (TIMI flow 0-3), and retrograde filling was graded on a 0-3 scale (collateral grade 0-3). TIMI flow grade and retrograde collateral grade in every lesion predicted region segment were summed to indicate the total segmental epicardial flow. Out of the 594 segments, 369 were associated with a severe lesion. Among them, significantly higher average perfusion and metabolic activities were found in segments of good epicardial filling (summed epicardial flow > or = 3) than in the territories of limited epicardial flow (summed score < 3): 65.4 +/- 17% vs 45.6 +/- 10 (P = 0.001%) and 68.6 +/- 16% vs 47.4 +/- 11% (P = 0.0004), respectively. However, when we analysed the predictive value of angiographically detectable good epicardial flow for positron emission tomography viability criteria then the positive predictive value was found to be as low as 0.5, while the negative predictive value was considerably higher (0.82). After myocardial infarction, angiographically detectable limited epicardial flow reveals scarred segments while good epicardial contrast filling does not necessarily indicate maintenance of nutritive function.