Blood Pressure: The Lower, the Better

Hypertension is one of the major modifiable risk factors for cardiovascular (CV) morbidity and mortality. It was recently shown that 7.6 million early deaths and 92 million disabled years are attributed to hypertension (1). Lowering blood pressure (BP) reduces CV morbidity and mortality. The benefit achieved in most hypertension outcomes studies was attributed to BP reduction, and the more aggressive the BP reduction, the greater the benefit (2,3). However, it is unclear what the target BP levels should be. Lewington et al. (4) showed in a large collaborative meta-analysis that included 1 million adults with no previous vascular disease that usual BP is strongly and directly related to vascular (and overall) mortality, without any evidence of a threshold down to at least 115/75 mmHg. This observation led clinicians to believe that BP should be lowered to the lowest tolerable levels. Some of the guidelines even adopted this approach and recommended lowering BP to <140/90 mmHg in all hypertensive patients, including the elderly, and to <130/80 mmHg in diabetic and high-risk patients (5,6). The present review will analyze the available data showing that the notion “the lower, the better” is not evidence based and that there is evidence that lowering BP too aggressively may even be harmful. One of the largest trials that addressed the question of what should be the optimal BP was the Hypertension Optimal Treatment (HOT) trial (7). This prospective study enrolled 18,790 patients who were randomly assigned to one of three diastolic BP target groups: ≤90, ≤85, or ≤80 mmHg. Mortality and CV morbidity were not different in the three different target groups, suggesting no benefit of lowering diastolic BP to <90 mmHg. However, instead of accepting the findings of the randomized trial as designed and drawing the right conclusion, the authors did …