Left ventricular hypertrophy and renin-angiotensin system blockade.

The renin-angiotensin system (RAS), an important control system for blood pressure and intravascular volume, also causes left ventricular hypertrophy (LVH) and fibrosis. The main causal mechanism is the increase in blood pressure, which leads to increased left ventricular wall stress; however, aldosterone release from the adrenals and (more controversially) the direct action of angiotensin II on the cardiomyocytes also play a role. Large clinical trials evaluating the blockade of the RAS with angiotensin-converting enzyme inhibitors or angiotensin receptor blockers have demonstrated an ability to prevent progression and induce regression of left ventricular mass, thereby reducing the significant and independent cardiovascular risk conferred by LVH. Regression of left ventricular mass is also achieved by other medication classes, but the RAS blockers have an additional beneficial effect for the same blood pressure reduction, for which the mechanism is not entirely clear. Studies comparing the efficacy of angiotensin-converting enzyme inhibitors versus angiotensin receptor blockers to achieve LVH regression have not demonstrated any clear benefit of one class over the other.