Background: The Coronary Artery Surgery Study (CASS) Registry is used to evaluate the effect of various baseline clinical and angiographic factors on mortality after acute out-of-hospital myocardial infarction (MI) in patients with and without prior coronary bypass surgery.
Methods and results: Among the CASS Registry patients, there were 985 medical and 369 surgical patients who had an MI out of the hospital within 3 years after enrollment. In the medical group, 20% died before hospitalization. Medical patients with baseline three-vessel disease or left ventricular (LV) dysfunction were at high risk of immediate death. For medical patients who were hospitalized with MI, mortality was higher for older patients and those with severe angina as well as for those with extensive disease and LV dysfunction. The total 30-day mortality for medical patients was 36%. In the surgical group, 12% died before hospitalization. Surgical patients with LV dysfunction or prior MI were at highest risk of immediate death. For surgical patients hospitalized with MI, mortality was significantly increased only for patients with baseline LV dysfunction. Mortality was not significantly higher for surgical patients with multivessel disease. The total 30-day mortality for surgical patients was 21%. The prior use of aspirin or beta-blockers was not associated with reduced mortality from subsequent MI for either medical or surgical patients. Although the prevalence of cigarette smoking was high among patients who had an MI, cigarette smoking did not alter the infarct-related mortality rate.
Conclusions: The surgical group had lower mortality rates than the medical group both immediately (p = 0.001), after hospitalization (p less than 0.0001), and at 30 days (p less than 0.0001).