COMPLEX CAUSES OF FATAL MYOCARDIAL-INFARCTION

It is too often deduced that myocardial infarction is due to coronary occlusion and that subsequent death needs no other explanation. But th e great majority of myocardial infarctions are not fatal, whether trea ted or untreated. There is, of course, some relation to the size of th e infarct and the presence or absence of complicating conditions such as diabetes mellitus or hypertension, but little attention has been di rected al the myriad of other events and processes influencing the cli nical course. Examples include the exact anatomic territory infarcted and whether it includes the sinus node or AV node or important neurore ceptors; whether many small arteries are occluded (especially downstre am of narrowed main coronary branches); whether the heart is hypertrop hied, dilated, infected, or infiltrated; and whether there may be intr acardiac, extracardiac, or intracranial neuropathological conditions t hat could destabilize cardiac electrical activity. It is now known tha t apoptosis plays a major role in myocardial infarction or ischemia. b ut it also occurs within the heart completely independently of Infarct ion. Then is also the vexing dilemma that an effective coronary collat eral circulation, which is determined primarily by transanastomotic pr essure gradient, is made less effective by exactly those treatments th at reestablish flow in an occluded coronary artery. Since thrombolysis and angioplasty are automatically considered urgent treatment for an occluded coronary artery, it is prudent to remember the complex causes that determine whether the patient lives or dies.