Comparison of amount of extent of coronary narrowing by atherosclerotic plaque and of myocardial scarring at necropsy in anterior and posterior healed transmural myocardial infarction.

The amount of cross-sectional area narrowing by atherosclerotic plaque in each 5-mm-long segment from the entire lengths of the right, left main, left anterior descending and left circumflex coronary arteries and the size, predominant location and extent of myocardial scarring were determined in 59 necropsy patients with a healed transmural myocardial infarct (MI). The mean number of the four major epicardial coronary arteries narrowed severely (76-100% in cross-sectional area) was 3.0 in the 37 patients with posterior MI and 2.6 in the 22 patients with anterior MI (p less than .025). The mean percent of severely narrowed 5-mm segments from all four major coronary arteries was similar in the anterior and posterior MI groups, 38% vs 46%. The patients with anterior MI, however, had a higher percentage of severely narrowed 5-mm segments of the left anterior descending than of the left circumflex but not the right coronary artery, 46% vs 25% (p less than 0.001) and 40% (NS). The patients with posterior MI had a higher percentage of severely narrowed segments of the right and left circumflex coronary arteries than of the left anterior descending artery, 55% and 51% vs 32% (p less than 0.05). The anterior MI group had, on the average, larger left ventricular scars than the posterior MI group (20% vs 9%, p greater than 0.002) and more frequent scarring of the ventricular septum, 16 patients (73%) vs six patients (16%) (p less than 0.001).