Summary:To investigate the pathophysiology of cardiac free wall rupture (cardiac rupture) following acute myocardial infarction (AMI), and to clarify whether reperfusion therapy prevents cardiac rupture, 1,329 cases of AM1 (conventional therapy group: 807 cases and reperfusion therapy group: 533 cases) were studied retrospectively. The overall incidence of cardiac rupture was 2.3% (2.7% in the conventional therapy group vs. 1.7% in the reperfusion therapy group). Patients with cardiac rupture were divided into two subgroups according to the time interval from the onset of AM1 to cardiac rupture (early rupture S72 h and late rupture 24 days). The indices of initial evolution of AM1 was a significant risk of early cardiac rupture. The reperfusion therapy group showed significantly lower incidence of late rupture (0.4 vs. 1.5% in conventional therapy group; p