Histopathological study of cardiac rupture following myocardial infarction with and without thrombolytic therapy.

The characteristics of cardiac rupture associated with thrombolytic therapy for acute myocardial infarction (MI) were studied in the hearts of 10 autopsy patients, 7 men and 3 women aged 41-80 years (mean 59.9 +/- 13.2 years), who died of rupture of the free wall of the left ventricle following acute MI. The site of rupture was examined histologically and the percentage areas of living myocytes, the processes of organization, necrosis and degeneration, and hemorrhage were compared in four patients who received thrombolytic therapy (group R) and six patients without thrombolytic therapy (group N). There were four pathological findings at the site of rupture: necrosis, neutrophil infiltration, hemorrhage, and evidence of the process of absorption. Group R consisted of two patients with hemorrhage, one with absorption, and one with unsuccessful reperfusion and neutrophilic infiltration. Group N included three patients with necrosis, two with neutrophilic infiltration, and one with hemorrhage. The percentage area involved by necrosis and degeneration was significantly lower in group R than in group N. Therefore, local stress produced by more surviving myocardium around the smaller necrosis area and the weakness of myocardium due to hemorrhage and absorption may provoke cardiac rupture in acute MI patients receiving thrombolytic agent.