Ambulatory blood pressure: the San Francisco experience.

Results obtained at the University of California in San Francisco with the Remler M-2000, patient-activated, semi-automatic portable blood pressure recorder were reviewed. The automated recordings were accurate and reproducible in comparison with simultaneous readings obtained with a conventional sphygmomanometer. Daytime pressures in ambulatory patients were correlated reasonably well with office blood pressures (r = 0.63-0.69), but in 80% of the patients ambulatory blood pressures were lower than office blood pressures, and the disparity between the two tended to increase as office blood pressures rose. Average ambulatory blood pressure was better correlated than office blood pressure with the degree of target-organ damage and the presence of cardiovascular complications. Among patients with an equivalent office blood pressure, those with a large office-ambulatory blood pressure disparity or a relatively low ambulatory blood pressure had less target-organ damage than those with a high ambulatory blood pressure or a small ambulatory-office blood pressure disparity. Beyond the well known and powerful effect of age on prognosis, the office blood pressure level and the presence of target-organ damage, such as left ventricular hypertrophy, the ambulatory blood pressure level provided additional prognostic information. Thus patients with a low ambulatory blood pressure, in relation to the level predicted from the office blood pressure, had a better prognosis, and were less likely to develop clinical events over a 10-year period, than patients with higher ambulatory blood pressure levels. This was confirmed in patients with both uncomplicated and complicated hypertension.