BLOOD-PRESSURE VARIABILITY - CLINICAL IMPLICATIONS AND EFFECTS OF ANTIHYPERTENSIVE TREATMENT

Hypothesis on relationship between blood pressure variability and end- organ damage: Several studies have shown that the cardiovascular compl ications of hypertension are more closely related to ambulatory 24-h o r daytime average blood pressure than to office readings. A few studie s have also provided evidence that in hypertensive patients, not only average ambulatory blood pressure but also the degree of blood pressur e variability is significantly and independently related to the end-or gan damage associated with hypertension. Limitations of previous studi es: A common limitation of previous studies is that they were based on cross-sectional or retrospective observations, so that the correlativ e evidence they provide does not allow the relationship between blood pressure variability and end-organ damage to be interpreted causally. Evidence from recent studies: Recent evidence from follow-up observati ons has strongly supported the hypothesis that blood pressure variabil ity is prognostically important in hypertensive patients. These findin gs suggest that optimal antihypertensive treatment should aim not only to reduce mean blood pressure levels, but also to reduce the degree o f blood pressure fluctuation. Effects of antihypertensive drugs: Unfor tunately, while most new antihypertensive drugs seem to be effective i n reducing 24-h mean blood pressure levels, they are frequently unable to reduce 24-h blood pressure variability, which is often increased d uring treatment when expressed in normalized units. The development of drugs that guarantee a constant and uniform reduction in blood pressu re over 24 h may, in principle, offer a further advantage by preventin g the increase in 24-h blood pressure fluctuations that may follow the administration of short-acting antihypertensive agents. Trough:peak m easurements of blood pressure: The trough :peak ratio, proposed as an arithmetic indicator of the duration of the antihypertensive effect of a drug, may be a useful measure of the occurrence of a smooth reducti on in blood pressure over 24 h. The possibility of obtaining an additi onal reduction in cardiovascular risk for hypertensive patients by min imizing the net trough:peak effect of antihypertensive drugs is thus a n important issue for future studies.