Impact of systolic blood pressure on cardiovascular prognosis.

Traditionally, diastolic rather than systolic blood pressure has been regarded as the main risk factor for cardiovascular complications in hypertension. While this remains valid for clinical hypertensive emergencies (accelerated and malignant hypertension), it is becoming increasingly clear that the risk of incurring the more distant cardiovascular complications in chronic 'benign' hypertension is associated with the systolic rather than the diastolic component of arterial pressure. Assessment of increased systolic pressure as a risk factor in its own right has been based on three epidemiological approaches. First, the impact of systolic pressure per se was examined by statistical evaluation of prospectively studied populations with different blood pressures. Second, selected subgroups with 'isolated' systolic hypertension were followed up. A third assessment was based on the results of therapeutic trials. All three assessments confirm that systolic pressure is likely to become the main criterion in the evaluation of hypertension, particularly in the elderly.