Instantaneous nonarrhythmic cardiac death in acute myocardial infarction.

From a group of 663 patients with acute myocardial infarction, 15 patients were identified with the syndrome of sudden loss of consciousness not preceded by symptoms of cardiac or respiratory failure or cardiac arrhythmias. The syndrome was accompanied by normal sinus rhythm, as assessed by electrocardiogram, but by neither a palpable pulse nor audible heart sounds. Seven of these patients had postmortem studies, and clinicopathologic correlations are presented. This syndrome has accounted for 68 percent of in-hospital monitored sudden deaths due to myocardial infarction. Four possible mechanisms are reviewed. These patients are presented to identify the problem of nonarrhythmic cardiac arrest in acute myocardial infarction and to stimulate new thoughts concerning etiology and management.