Mechanism(s) of Systolic Blood Pressure Reduction and Drug Therapy in Hypertension

Abstract

Antihypertensive drug therapy is a major modality of cardiovascular (CV) disease prevention, especially for stroke, congestive heart failure, and renal insufficiency. Coronary risk is also consistently prevented by antihypertensive treatment, but to a lesser extent.1–4 The Prime Study2 has shown that drug-induced blood pressure (BP) reduction in hypertensive subjects is associated with a significant decrease of coronary risk. However, when treated and untreated subjects are compared, at any given value of systolic BP (SBP), this risk remains higher in treated than in untreated subjects, suggesting the persistence of residual coronary complications. Results of therapeutic trials also indicate that coronary risk is associated with a particular hemodynamic pattern in treated hypertensive subjects.3 Although diastolic BP (DBP) is significantly lowered by drug treatment to <90 mm Hg (80% of the patients), SBP remains above 140 mm Hg in 60%, indicating an increase of pulse pressure (PP), which is the difference between SBP and DBP.4 It is widely accepted that SBP and PP rise sharply with age and that this increase is a major manifestation of vascular aging and stiffening, which are now considered major predictors of CV risk, independent of the mean BP (MBP) level.4 The purpose of this review is to analyze the mechanism(s) of SBP in untreated and chronically treated hypertensive subjects and to determine which pathophysiological factors are susceptible to attenuating consistently coronary and CV complications in hypertensive populations. Ventricular ejection in humans is associated with 2 principal events. First, the coronary circulation is transiently interrupted, as the principal consequence of cardiac contraction, and, second, an acute shock of stroke volume against the aortic wall is observed (Figure 1). Then, the BP curve may be considered as a wave, which travels along the arterial tree at a given speed, the pulse wave velocity (PWV). …