Endocardial tears and rupture tracts of left ventricular ruptures during acute myocardial infarction: an autopsy study of 50 out-of-hospital sudden death cases.

We pathologically evaluated endocardial tears and rupture tracts of left ventricular ruptures during acute myocardial infarctions (50 sudden out-of-hospital death cases; 28 men and 22 women; age range 42-88 years; mean age 68.4 years). Endocardial tears were frequently seen at or near the base of the papillary muscles (54%) or in the area where the septum meets the free wall (42%). The endocardial tear was longer in the adjacent septum (mean 2.1+/-1.0cm) than at the papillary muscle base (mean 1.0+/-0.8cm). Accessory tears were observed near the main endocardial tear in about half of the cases (44%). The rupture tract was located well within the infarcted area in 88% and at the border of the infarcted and normal myocardium in 12%. Mature fresh thrombus was found on most main endocardial tears. In most rupture tracts, the thrombus was more mature in the subendocardial than in the subepicardial zone. Morphologically, this study confirmed that most cardiac ruptures start with an endocardial tear at or near the base of the papillary muscles or in the area where the septum meets the free wall, and rapidly progress independent of the histopathologic age of the infarction.