Blood pressure J-curve: is it cause or effect?

Clinical trials have demonstrated that antihypertensive therapy leads to the prevention of stroke, consistent with that predicted by epidemiological data. In contrast, in the same studies, the reduction in coronary artery disease events has been substantially less than predicted. Many possible explanations have been proposed to account for this shortfall in the reduction of disease produced by antihypertensive therapy. One suggestion has been that too great a fall in diastolic pressure during treatment actually increases the risk of myocardial infarction. A substantial body of data taken from clinical trials has consistently demonstrated a J-shaped association of diastolic pressure and coronary events. Some studies suggest that this J-shaped association is limited to those with coronary disease, and that the J-phenomenon is the result rather than the cause of atherosclerotic disease of the aorta. A prospective study is underway to resolve this issue. Meanwhile, the cautious physician is advised to seek a moderate decline in diastolic pressure to a level greater than 80 mmHg.