Long-term blood pressure variability: an emerging cardiovascular risk factor.

Clinical trials and observational studies have demonstrated that long-term systolic blood pressure variability derived from repeated measurements of visit-to-visit clinic blood pressure is an important predictor of cardiovascular outcomes, independent of average levels of systolic pressure. Even in patients with well-controlled blood pressure (<140/90 mmHg), high systolic blood pressure variability confers an increased risk of cardiovascular events. Systolic blood pressure variability is currently derived from several measurements of visit-to-visit clinic blood pressure and expressed as the standard deviation of systolic pressure. Values in excess of 12 are indicative of high systolic blood pressure variability. Ongoing studies aim to determine whether home blood pressure monitoring may be an alternative way of measuring blood pressure variability. Evidence from several clinical trials shows that long-acting calcium-channel blockers, such as amlodipine, and thiazide-like diuretics are the only antihypertensive drugs that reduce longterm systolic blood pressure variability, and should be used preferentially in patients with high variability.