Reflections on Masked Hypertension

T he pioneering articles by Sir George Pickering and Maurice Sokoloff have amply illustrated the potential of ambulatory blood pressure monitoring, especially in the diagnosis of hypertension. Recent work has highlighted the prognostic value of ambulatory blood pressure (BP) in predicting cardiovascular events over and above office BP. Several patterns have been described in the ambulatory BP curve, A lot of attention has been devoted to isolated office hypertension (elevated office BP and normal ambulatory day BP). Recently, another feature was described consisting of normal office BP but elevated ambulatory BP. This condition was called masked hypertension. Several aspects of this condition still need clarification. First, it is not clear yet whether the same definition can be applied for treated and untreated hypertension. Much more important, the prognostic value of masked hypertension is still under investigation. In a recent article, it was shown that masked hypertension has a negative impact on prognosis in treated elderly hypertensive patients. In the present issue of the American Journal of Hypertension, Pierdomenico et al further analyzed the question. They evaluated cardiovascular events during 5 years in 340 patients with responder hypertension (normal office and daytime ambulatory BP) and 126 with masked hypertension (clinic BP 140/90 mm Hg and daytime BP 135/85 mm Hg). After adjustment for several covariates, including clinic BP, Cox regression analysis showed that cardiovascular risk was significantly higher in masked hypertension compared to responder hypertension (relative risk [RR] 2.28, 95% CI 1.1–4.7, P .05). This information is important as it confirms the data of Bobrie et al and certainly follows logical thinking: the longer time BP is high, the higher the risk for cardiovascular events. Careful analysis of this article warrants waiting for further confirmation. The population studied in this study may be different from that seen in regular hypertension clinics. The investigators come up with a very high prevalence of masked hypertension (340 of 742 patients). For reference, in the Office vs. Ambulatory (OvA) study, prevalence was 143 of 1963. Also the total number of