Effects of type A behavioral counseling and severity of prior acute myocardial infarction on survival

Abstract

The hypothesis under investigation was that the beneficial effect of type A behavioral counseling on survival after acute myocardial infarction (AMI) was conditional on the functioning of the cardiovascular system, as determined by the severity of the prior AMI. Subjects were 862 nonsmoking coronary patients in the San Francisco Bay Area, randomized in 1978 to receive, over 4.5 years, cardiac counseling or cardiac counseling plus type A behavioral counseling. Sixteen baseline factors plus an interaction term (severity of AMI X behavioral counseling) were evaluated for their prognostic significance. Behavioral counseling was not a significant predictor of coronary death in the total cohort, but the interaction between counseling and severity of the prior AMI was (p less than 0.05). Thus, the total cohort was divided into 2 subgroups of mild or serious prior AMI, and independent predictors of survival were isolated within each subgroup. In the subgroup with mild prior AMI, independent predictors were anterior AMI (p = 0.02), plasma cholesterol (p = 0.02) and behavioral counseling (p = 0.05). In the subgroup with serious prior AMI, none of the factors evaluated made a significant independent contribution. These findings suggest that a reduction in type A behavior may exert the greatest protection against coronary death in that subgroup of patients for whom the biologic aspects of coronary artery disease are not advanced. They also demonstrate the importance of considering the level of cardiac functioning before determining predictors of survival or optimum postcoronary care.