Untreated Masked Hypertension and Subclinical Cardiac Damage: A Systematic Review and Meta-analysis

AIM: Data on the association of masked hypertension (MH) (i.e., normal office and elevated out-of-office blood pressure (BP)) with cardiac damage are scanty. We performed a meta-analysis in order to provide a comprehensive information on subclinical cardiac alterations in subjects with MH. DESIGN: Studies were identified by the following search terms: "masked hypertension," "white coat normotension," "isolated ambulatory hypertension," "left ventricular mass," "left ventricular hypertrophy," "cardiac damage," and "echocardiography." Full articles published in English language providing data on left ventricular (LV) mass and/or prevalence of LV hypertrophy in MH, as assessed by ambulatory BP monitoring, were considered. RESULTS: Overall, 4,884 untreated subjects (2,467 normotensive, 776 MH, and 1,641 sustained hypertensive individuals) of both genders included in 12 studies were analyzed. LV mass index showed a progressive increase from normotensive (79.2 ± 0.35 g/m(2)) to MH (91.6 ± 4.0 g/m(2)) (standard difference in means (SDM): 0.50 ± 0.11, confidence interval (CI): 0.28-0.73, P < 0.01) and to hypertensive subjects (102.9 ± 3.3g/m(2)) (SDM: 0.22 ± 0.07, CI: 0.09-0.35, P < 0.01). After assessing data for publication bias, the difference between groups was still significant. CONCLUSIONS: Our findings support an association between MH and increased risk of LV structural alterations compared to true normotensive individuals. Due to the worse cardiovascular prognosis associated with subclinical cardiac damage, subjects with MH should be carefully screened in order to detect hypertensive organ damage and provide appropriate therapeutic interventions.