Is Exaggerated Exercise Blood Pressure Increase Related to Masked Hypertension?

O ffice combined with out-of-office (i.e., ambulatory or home) blood pressure (BP) determination allows to identify four BP patterns, defined as true normotension (normal office and out-ofoffice BP), sustained hypertension (elevated office and out-of-office BP), white coat hypertension or isolated clinic hypertension (elevated office and normal out-of-office BP) and the final pattern, alternatively referred to as isolated ambulatory hypertension, isolated home hypertension or masked hypertension (MH; normal office and elevated out-ofoffice BP). The term MH was first used in the early 2000s by Tom Pickering to describe subjects in whom hypertension was not detected by routine office BP measurements.1 A growing body of evidence indicates that MH is associated with prevalent organ damage and, more importantly, this condition entails an increased incidence of cardiovascular events in longitudinal studies.2 This is because out-of-office BP, either monitored at home or in ambulatory conditions over the 24 h, has a greater prognostic value than office or clinic BP readings. Several issues related to this condition are still debated; in particular, about the methods (i.e., ambulatory or home BP) that more reliably identify subjects at risk of MH,3 the actual prevalence of this harmful condition, its demographic/clinical correlates, and reproducibility over time. In this issue of the journal, Sharman et al.4 provide a further contribution in this field, by reporting data on the association between MH, left ventricular remodeling, and exaggerated BP response to maximal treadmill exercise (i.e., systolic BP ≥210 mm Hg in men and >190 mm Hg in women or diastolic BP >105 mm Hg in both genders) in a sample of 72 nondiabetic subjects free of cardiovascular disease. The authors found that out-of-office hypertension, defined as daytime BP values ≥135/85 mm Hg during 24-h monitoring, was present in the majority of the study population (58%) and was associated with a higher left ventricular mass, left ventricular relative wall thickness, and prolonged mitral deceleration time. Interestingly, independent correlates of exercise systolic BP were male gender and office BP; this observation suggests that men with high-normal office BP values or prehypertension are at greater risk of hypertensive responses to exercise and of MH. Indications that both high-normal office BP levels and male gender have an independent positive value in predicting MH have been consistently provided by large-scale studies attempting to identify factors related to this phenotype.2 The independent association between MH, abnormal BP responses to exercise and left ventricular mass found in the present study confirms and expands previous evidence about the pivotal role of BP variations during daily activities in determining subclinical cardiac damage. The present finding also conveys the important general message that unexplained alterations of left ventricular structure and geometry in individuals with normal office BP may relate to MH. In conclusion, despite limitations related to the small sample and the lack of a control group, the study by Sharman reinforces the view that ambulatory BP monitoring in subjects with hypertensive BP responses to exercise should be regarded as an effective tool to unmask MH.5