Relation of Blood Pressure Response to Therapy and the Occurrence of Myocardial Infarction and Stroke

In clinical trials of antihypertensive therapy, the extent of the reduction in myocardial infarctions and stroke has been found to differ substantially. To determine whether blood pressure response to antihypertensive treatment might explain these differences, the records of 2.836 participants in a systematic antihypertensive treatment program were searched to detect cases of ischemic disease occurrence. During 7 years of follow-up. 40 myocardial infarctions (MI) and 12 strokes (S) were identified (incidencesMI = 6.0 per 1000 person-yearsS = 1.8 per 1000 person-years). At entry into the study, each of the patients who later would go on to suffer an MI or stroke was paired with a control patient matched for age. sex. race, treatment status (whether receiving antihypertensive therapy or not), and blood pressure level. Each follow-up year was divided into two 6-month sectors and the average blood pressure computed for each sector. Blood pressure changes were defined as the difference between the initial and the computed blood pressures for any particular sector. Blood pressure levels and changes were analyzed, for both cases and controls, at the first and second sectors and at the sector preceding the ischemic event. For myocardial infarction patients who had entered the program with and without antihypertensive therapy, the computed mean blood pressures and changes were similar to those of their matched controls. Prevent sector blood pressures were not different from those of controls. In the case of stroke patients. however, higher mean values and sustained diastolic blood pressure levels were observed compared to values for controls. These findings indicate that blood pressure response to antihypertensive therapy is a strong predictor of stroke. By contrast, myocardial infarction patients could not be distinguished from matched controls on the basis of the blood pressure course during treatment. Other factors, including clinical and behavioral characteristics. as well as biochemical parameters (namely, cholesterol and blood glucose), were strongly associated with the occurrence of myocardial infarction. Management of the hypertensive patient might therefore be improved by careful attention to these other factors, in addition to blood pressure