Reverse dipping and subclinical cardiac organ damage: a meta-analysis of echocardiographic studies

AIM: Available evidence on the association between reverse dipping pattern and subclinical cardiac damage is scanty. We performed a systematic meta-analysis of echocardiographic studies in order to provide an updated and comprehensive information on this issue. METHODS: The PubMed, OVID-MEDLINE, and Cochrane library databases were analyzed to search English-language articles published from January from the inception up to 31 July 2020. Studies were identified by using MeSH terms and crossing the following search items: 'reverse dipping', 'nondipping', 'inverted dipping', 'ambulatory blood pressure', 'cardiac damage', 'hypertensive heart disease', 'left ventricular mass', 'left ventricular hypertrophy', and 'echocardiography'. RESULTS: Data from 14 studies including 1429 patients with reverse dipping, 2584 dippers and 3508 nondippers were considered. Left ventricular (LV) mass index and relative wall thickness were greater in reverse dippers than in dippers (SMD: 0.40 ± 0.04 g/m2, P < 0.0001; 0.31 ± 0.07, P < 0.0001) and nondippers (SMD: 0.25 ± 0.04 g/m2, P < 0.0001; 0.21 ± 0.07, P = 0.004). The reverse dipping group had an increased risk of LV hypertrophy compared with dipping (OR = 1.85, CI 1.47-2.32, P < 0.0001) and nondipping group (OR = 1.45, CI 1.19-1.78, P < 0.0001). A significant progressive reduction in the E/A ratio, paralleled by an increase in left atrium diameter occurred from dippers, to nondippers and reverse dippers. CONCLUSION: The present meta-analysis provides a novel piece of information about the unfavourable association between the reverse dipping pattern and subclinical cardiac alterations and suggests that the detection of this blood pressure phenotype may identify individuals at increased risk for subclinical organ damage.