PROGNOSTIC IMPLICATIONS OF ABPM

PD Dr.Peter Trenkwalder
Department of Internal Medicine, Starnberg Hospital
Ludwig Maximilian University Munich
Osswaldstr. 1, D - 82319 Starnberg, Germany

INTRODUCTION Numerous epidemiological studies have demonstrated that high blood pressure (BP) values are closely correlated with an increased cardio-vascular and cerebrovascular morbidity and mortality. In long-term intervention trials treatment of hypertension with antihypertensive agents could reduce the cerebrovascular event rate by 35-40% and the cardiac event rate by 15-20%. All these studies have been performed with office BP measurements. In the last decade ambulatory blood pressure monitoring (ABPM) with modern portable devices has become available world-wide. Actually the question remains, whether the increased information provided by ABPM (e.g. about the total circadian BP profile) can better predict hypertensive complications and whether treatment guided by ABPM will improve the outcome of hypertensive patients.

REVIEW DATA More than a hundred cross sectional studies studies have shown that 24 hour ABPM is a better predictor than office BP for surrogate markers and true target organ damage of hypertension such as left ventricular mass and wall thickness, arterial wall thickness, systolic and diastolic left ventricular dysfunction, proteinuria (including microalbuminuria) in patients with diabetic or hypertensive nephropathy, retinopathy, brain damage and an overall organ damage score. Only few prospective studies using ABPM are hitherto available: Perloff et al. demonstrated more cardiovascular events in patients with both increased office and ambulatory BP, Verdecchia et al. showed an increased event rate in hypertensives with impaired day-night rhythm, Mancia et al. reported a close correlation between drug-induced regression of left ventricular mass and changes in ambulatory BP.

ABPM can easily diagnose the „white coat effect", i.e. the raise in BP during clinical visits, and „white coat hypertension", i.e. increased BP in the office compared to normal BP during the remaining day. Whether white coat hypertension is a pure benign disorder without increased risk or a borderline stage between normotension and hypertension remains to be determined.

CONCLUSION ABPM improves diagnostic categorization of hypertension and evaluation of target organ damage. Future prospective long-term studies must determine whether diagnosis and treatment based on ABPM (in addition or instead of office BP) will finally improve the prognosis of hypertensive patients.