Background: Experimental clinical observations suggest that fibrinolysis (FL) in acute myocardial infarction, even though reducing global mortality, is associated with an increasing incidence of death in the first 24-48 h. The responsible mechanism is not yet known, although available evidence supports heart rupture as the possible cause.
Methods: We studied 154 patients at autopsy who died of cardiac causes from January 1, 1994 to December 31, 2005 among a cohort of 2260 patients who were admitted for ST-elevation myocardial infarction. They were divided into three therapeutic groups-- FL, coronary angioplasty (PTCA) and conventional therapy (CT)--in order to assess the incidence of cardiac rupture and compare it with the other causes of cardiac death.
Results: Of the 896 patients (39.7%) who were treated with FL, 57 (6.4%) died; of the 804 (35.6%) treated with PTCA, 40 (5.05%) died, and of the 560 (24.7%) treated with CT, 57 (10.2%) died (p < 0.05 in the two first groups vs CT). We studied at autopsy 154 patients (mortality 6.7%). The mean admission delay was 5.05 h in the FL group, 7.04 h in the PTCA group, and 7.05 h in the CT group. Cardiac death occurred on average after 13 h in the FL group, after 15 h in the PTCA group, and after 19 h in the CT group. The cause of death was due to cardiac rupture in 56 patients (36.5%), to shock in 55 patients (35.7%), to electromechanical dissociation in 29 patients (18.8%), and to cardiac failure in 14 patients (9%). In the FL and PTCA groups, cardiac rupture was the major, and also the earliest (10 e 12 h, respectively), cause of death, whereas in the CT group cardiac shock (13 h) was the major cause of death. Anterior myocardial infarction (n = 104, 65%) was more prevalent in deceased patients, whereas inferior myocardial infarction was found in the other 50 cases (35%). Cardiac rupture was more prevalent in anterior myocardial infarction. In the FL and PTCA groups, histological examination showed unusual hemorrhagic infiltration in the necrotic areas with presence of leukocytes.
Conclusions: Our study shows that cardiac rupture is the major cause of death in patients with ST-elevation myocardial infarction treated with FL and PTCA, suggesting that mechanical and lythic reperfusion injury, in coagulative necrosis, may represent a further cause of cardiac rupture that occurs early or within the first hours.