Ischemia at a distance after acute myocardial infarction: a cause of early postinfarction angina.

Whether an acute myocardial infarction due to occlusion of one major coronary artery can cause ischemia in the distribution of a second narrowed coronary artery by the mechanism of collateral interruption (i.e., ischemia at a distance) is not known. To study this, we reviewed 128 consecutively autopsied patients with acute fatal myocardial infarcts and identified 20 patients in whom angina, associated with transient ischemic ECG changes, developed early after infarction. All 20 patients had severe (>75% narrowing) twoor three-vessel coronary artery disease with a myocardial infarction in the distribution of a freshly occluded coronary artery. Twelve patients had postinfarction angina and transient ST-T-wave changes in the electrocardiographic zone of the occluded vessel (i.e., postinfarction ischemia in the infarct zone). In eight patients, however, postinfarction angina and transient ST-T-wave changes developed in the electrocardiographic zone of a nonoccluded but critically narrowed vessel (i.e., ischemia at a distance). Compared with patients who had ischemia in the infarct zone, patients who had ischemia at a distance had a lower final Killip class, more deaths due to ventricular arrhythmias, and significantly smaller infarcts at autopsy (p < 0.005). Thus, death in the patients with ischemia at a distance appeared to be related more to the ischemic events than to the quantity of myocardium lost. During a 6-month period, four additional patients with ischemia at a distance were identified from 40 consecutive patients admitted to the coronary care unit with documented myocardial infarction. The clinical course and pathologic findings in these patients suggested that it was not the acute infarction that led to their deaths, but rather ischemia at a distance. This concept of ischemia at a distance not only extends our understanding of an ischemic border zone, but suggests a subset of early postinfarction patients who might be particularly suited for prompt cardiac catheterization with aggressive medical and surgical intervention.