J-curve phenomenon: a matter of debate.

T here is mounting evidence to confirm that hypertension activates multiple pathophysiological processes that lead to deterioration of the cardiovascular system. Since the reduction of blood pressure (BP) is accompanied by beneficial effects on cardiovascular and renal outcome, especially in subjects with uncomplicated hypertension, it has been suggested that lower achieved BP values— close to fully normotensive levels—could decrease the risk of adverse outcomes also in high-risk hypertensive subjects. However, a “J-curve phenomenon” has been observed in such patients, referring to an increased rate of cardiovascular events when BP levels fall below a level that is critical for organ perfusion. Although guidelines for the management of hypertension recommend a BP goal of <140/90 mmHg in the general population and <130/80 mmHg in diabetics, patients with renal, cerebrovascular or coronary artery disease (CAD), or organ damage, the majority of high-risk patients remain with poorly controlled BP. In this review we present data for and against the existence of the J-curve, considering cardiac, cerebral and renal events. We investigate the J-curve among diabetics, patients with renal dysfunction, and elderly subjects. New data challenging the speculation that we should pursue lower achieved BP levels for patients with a high stroke risk than for patients with a high cardiac risk are also analysed. Historical background