[Electromechanical dissociation in myocardial infarction. Anatomical-clincal study of 82 cases]

In our experience electromechanical dissociation (EMD) is the most common mechanism of fatal cardiac arrest in patients with acute myocardial infarction (AMI).

We reviewed retrospectively 82 autopsy cases of AMI in whom the medical record documented EMD as terminal cardiac arrest in order to outline the clinical and pathologic features of different subgroups: 26 cases with external cardiac rupture (CR) were compared with 56 cases without CR. In turn, inside the latter series, 16 cases of sudden EMD were compared with 40 cases of EMD occurring in the terminal phase of cardiac shock.

In comparison with those without CR, patients with CR showed at multiple regression analysis less evidence of left ventricular failure (p < 0.05); less extended infarct areas (p < 0.01); more frequent sudden EMD (p < 0.05). Most patients with CR had massive pericardial effusion; cardiac rhythm at the onset of EMD was seldom slow in those cases. In the group without CR no discriminant characteristics were found in cases of sudden EMD vs cases preceded by cardiac shock.

In case of CR EMD occurs in less extensively damaged hearts and is generally sudden; in AMI without CR EMD may affect patients with severe depression of pump performance, but not necessarily in shock. EMD after an AMI may result from several factors: cardiac tamponade is prevalent in the presence of CR; in cases without CR our data don't permit to conjecture a distinct pathogenesis for sudden EMD in comparison with cases preceded by shock.