Ageing and hypertension: the assessment of blood pressure indices in predicting coronary heart disease.

OBJECTIVE: To determine whether pulse pressure (PP), diastolic blood pressure (DBP), systolic blood pressure (SBP), or mean arterial pressure (MAP) is the superior haemodynamic predictor for the risk of coronary heart disease (CHD). METHODS: Age-related changes of blood pressure in normotensive and untreated hypertensive subjects in a population-based cohort from the Framingham Heart Study were characterized. The relationship between these blood pressure indices and risk of CH D over a 20-year follow-up period were then evaluated. RESULTS: There was a parallel linear rise in SBP, DBP and MAP from age 30-49 years, suggesting increased peripheral vascular resistance (PVR) in this age group. After age 50-60 years, DBP declined, PP rose steeply, and MAP levelled off, while SBP continued to show a linear increase, suggesting increasing predominance of large artery stiffness (LAS) in this middle-aged and elderly group. After adjusting for age, sex and other risk factors, MAP and DBP consistently underestimated PVR and risk of CHD. Systolic blood pressure fully represented PVR but frequently underestimated LAS and risk of CHD. Pulse pressure was superior to SBP as a surrogate marker for LAS and predictor of CHD risk in the presence of discordantly low DBP, but PP frequently underestimated PVR. CONCLUSIONS: In middle-aged and older subjects, at any given level of SBP > or = 120 mmHg, the risk of CHD rose with discordantly lower DBP, suggesting that the wider PP was driving the risk for CHD. These results suggest that total haemodynamic load, defined as the sum of pulsatile load (LAS) and steady-state load (PVR), is a major determinant of CHD risk.