Relation of healed transmural myocardial infarct size to length of survival after acute myocardial infarction, age at death, and amount and extent of coronary arterial narrowing by atherosclerotic plaques: Analysis of 70 necropsy patients

Abstract

The percent of left ventricular wall (including ventricular septum) replaced by scar was determined in 70 necropsy patients with a healed transmural myocardial infarct (MI). The MI involved from 1% to 55% (mean 13%) of the left ventricular wall. The ages at death of the patients ranged from 25 to 82 years (mean 62) and did not signficantly correlate with MI size ( r = −0.12). Of the 70 patients, 41 (59%) had unequivocal histories of an acute MI: the interval from the MI to death in them ranged from 2 to 276 months (mean 50) and correlated negatively with MI size ( r = −0.32, p < 0.05), and the age at the MI ranged from 26 to 79 years (mean 58) and did not correlate with MI size ( r = −0.05). The four major epicardial coronary arteries were examined quantitatively in 56 patients; the number of coronary arteries with severe narrowing ranged from one to four (mean 2.9) and did not correlate with MI size ( r = −0.24). The mean MI size in the 12 patients with and in the 44 without severe narrowing of the left main coronary artery was identical (each 13%). The entire lengths of the right, left anterior descending, and left circumflex coronary arteries in the 56 patients were divided into 5 mm long segments and the amounts of cross-sectional area narrowing in each of the resulting 2489 segments were determined by histologic examination. The percent of 5 mm segments with severe (cross-sectional area narrowing 76% to 100%) narrowing by atherosclerotic plaques in each patient ranged from 3% to 93% (mean 44%) and did not correlate with MI size ( r = −0.20). When the 28 patients with an MI involving > 10% of the left ventricular wall were compared to those with an MI involving ≤ 10%, a similar overall percentage of 5 mm segments of coronary artery was severely narrowed (43% vs 42%). In addition, a similar percentage of segments was narrowed severely in each of the three major epicardial coronary arteries. Thus in our necropsy patients with a healed transmural MI, the MI size correlated with length of survival after an acute MI (in patients with definite histories of an acute MI) but not with age at death or with the amount, location, or extent of coronary arterial narrowing by atherosclerotic plaques.