Prognostic value of 24-hour blood pressure variability.

Objectives: Evaluation of the prognostic value of 24-h blood pressure averages and 24-h blood pressure variability.

Design: After an initial thorough clinical and laboratory evaluation which included 24-h continuous ambulatory blood pressure monitoring, a group of hypertensive patients were re-examined after an average of 7.4 years. End-organ damage at the follow-up visit was related to different measures of blood pressure levels and variability obtained at the initial or the follow-up visit or both.

Methods: Seventy-three patients with essential hypertension of variable severity, in whom ambulatory blood pressure was monitored intra-arterially for 24 h (Oxford technique) were re-examined at a follow-up visit (including echocardiographic assessment of left ventricular mass index) 1-13 years later (mean 7.4 years). The severity of end-organ damage was quantified by a score and related to clinic blood pressure at follow-up and to (1) clinic blood pressure, (2) 24-h blood pressure mean, (3) 24-h short-term and long-term blood pressure variability, and (4) end-organ damage, all assessed at the initial visit (multiple regression analysis).

Results: The set of independent variables considered was significantly related to end-organ damage at follow-up (R = 0.51). The individual variables most important in determining end-organ damage at follow-up were clinic blood pressure at the follow-up visit (P < 0.01), the initial level of end-organ damage (P < 0.05) and long-term blood pressure variability (among half-hour standard deviation of 24-h mean blood pressure) at the initial evaluation (P < 0.05). The prognostic individual weight of the other haemodynamic parameters considered was less and not statistically significant.

Conclusions: The results confirm that the level of blood pressure achieved by treatment and the degree of end-organ damage at the time of initial evaluation are important determinants of future end-organ damage related to hypertension. They also constitute the first longitudinal evidence that the cardiovascular complications of hypertension may depend on the degree of 24-h blood pressure variability.