Purpose: To compare morphological features of myocardial infarction (MI) from patients with any epicardial coronary artery narrowed at some point more than 70% (severe coronary atherosclerosis--SCA) with those from patients with either no coronary atherosclerosis or only mild (less than 70%) atherosclerosis.
Methods: Necropsy findings from 194 patients who died due to MI, 174 patients with and 20 without SCA. Ages ranged from 21 to 82 (mean 60) years.
Results: Mean age was 60 years in the cases with SCA and 56 in the case without it; nevertheless, age distribution was different (p = 0.023), due to the existence of more patients under age 40 in the group without SCA. There was no significant difference concerning sex (31.0% of female patients in the group with SCA and 35.0% in the other group, p = 0.718), mean heart weight (500 g and 506 g), distribution of cases according to time of evolution of MI in recent only, old only or both (cases with SCA--36.2%, 28.2% and 35.6%; cases without SCA--45.0% and 20%; p = 0.666), left ventricular wall committed by the MI (p = 0.715), incidence of hemorrhagic infarction (with SCA--8.6%; without SCA--15.0%; p = 0.406), left ventricular rupture (with SCa--5.17%, without SCA--10.0%; p = 0.719) and left ventricular aneurysms (with SCA--12.1%, without SCA--15.0%; p = 0.316). An association was found between coronary atherosclerosis and recent (p = 0.046) and recanalized (p less than 0.001) thrombosis, but absent when only recent thrombosis and non-operated cases with recent MI were considered (p = 0.091).
Conclusion: Necropsy of fatal cases of MI were not significantly different in the presence or absence of severe atherosclerotic narrowing (greater than 70%) of epicardial coronary arteries, suggesting that this factor does not modify the natural history of MI.