15. Rabkin, S.W., Mathewson, F.A.L., Tate, R.B.: Prognosis after acute myocardial infarction: relation to blood pressure values before infarction in a prospective cardiovascular study. Am J Cardiol 40: 604-610, 1977.
The relation of preexisting hypertension to survival after myocardial infarction is uncertain, but it has been examined primarily in studies with limited data on previous blood pressure values. Therefore in the Manitoba Study cohort, 3,983 men under observation since 1948, the last recorded blood pressure before the first myocardial infarction as well as the change in blood pressure from a measurement made 5 years previously was related to survival after the infarction.
With use of the life table method, progressively increasing values for systolic or diastolic blood pressure were found to be associated with worsening prognosis. Subjects with a systolic pressure of 140 mm Hg or greater or a diastolic pressure of 90 mm Hg or greater had a significantly (P<0.05) lower survival rate up to 10 years after myocardial infarction than subjects with lower blood pressure levels. Large (20 mm Hg or more) positive or negative changes in systolic blood pressure were associated with significantly (P<0.05) lower survival rates within 3 months of the infarction but not thereafter.
To standardize the follow-up period, short-term mortality rates were based on data from patients under study for up to 1 month after myocardial infarction and long-term mortality rates on those from subjects under observation 1 month to 3 years after infarction. In multivariate analysis - after adjusting for the effect of age at infarction, previous evidence of angina pectoris or coronary insufficiency, previous episodes of left ventricular failure, transmural or nontransmural infarction and site (anterior or inferior) of transmural infarct - blood pressure was a significant (P<0.01) determinant of short term mortality and was the only significant (P<0.01) predictor of long-term mortality. Also in multivariate analysis, a change in blood pressure over a 5 year interval was significantly (P<0.05) associated with short-term mortality. Thus, blood pressure level and the magnitude of change in pressure from previous values are two significant indicators of prognosis after acute myocardial infarction.