Features of left ventricular hypertrophy in patients with metabolic syndrome with or without comparable blood pressure: a meta-analysis

The prevalence of metabolic syndrome (MS) has been on the rise over the past few decades, and this is associated with an increased incidence of target organ damage such as left ventricular hypertrophy (LVH). This meta-analysis aims to evaluate the features of LVH in MS patients with or without high blood pressure (BP). PubMed, Cochrane Library, Embase, Science Citation Index, and China Biology Medicine Disc, WanFang data, China National Knowledge Infrastructure database, and VIP were searched. Cross-sectional studies which directly compared LVH in hypertensive patients with MS and those with hypertension alone were identified. The following parameters were analyzed: systolic blood pressure (SBP), diastolic blood pressure (DBP), left ventricular mass (LVM), left ventricular mass index (LVMI), left ventricular mass/height(2.7) (LVM/h(2.7)), interventricular septum thickness (IVSt), left ventricular end-diastolic diameter (LVEDd), left ventricular posterior wall (LVPW), ratio of early to late diastolic peak flow velocity (E/A), and relative wall thickness (RWT). Data were extracted and analyzed by Cochrane Collaboration's RevMan 5.0 software. 14 studies involving 5,994 patients were included. In four studies, MS patients with comparable level of BP had higher SBP (mmHg) [Mean Difference (MD) = 2.28, 95 % confidence intervals (CI): -0.58 to 5.13], DBP (mmHg) (MD = 1.32, 95 % CI: -0.23 to 2.87), LVM (g) (MD = 42.10, 95 % CI: 6.92-77.28), LVMI (g/m(2)) (MD = 8.93, 95 % CI: 5.29-12.57), LVM/h(2.7) (g/m(2.7)) (MD = 5.40, 95 % CI: 2.51-8.29), IVSt (mm) (MD = 0.49, 95 % CI: 0.28-0.71), LVEDd (mm) (MD = 1.04, 95 % CI: -1.10 to 3.18), LVPW (mm) (MD = 0.75, 95 % CI: 0.13-1.37), RWT (MD = 0.06, 95 % CI: -0.00 to 0.12), and lower E/A (MD = -0.08, 95 % CI: -0.18 to 0.02) when compared to the patients with hypertension alone. In other ten studies, the hypertensive patients with MS exhibited higher levels of SBP (mmHg) (MD = 4.67, 95 % CI: 2.72-6.62), DBP (mmHg) (MD = 2.03,95 % CI: 1.40-2.65), LVM (g) (MD = 24.79, 95 % CI: 20.21-29.36), LVMI(g/m(2)) (MD = 9.22, 95 % CI: 2.81-15.64), LVM/h(2.7) (g/m(2.7)) (MD = 5.97, 95 % CI: 4.14-7.80), IVSt (mm) (MD = 0.63, 95 % CI: 0.58-0.69), LVEDd (mm) (MD = 1.11, 95 % CI: 0.42-1.80), LVPW (mm) (MD = 0.63, 95 % CI: 0.31-0.94), RWT (MD = 0.02, 95 % CI: 0.01-0.03), as compared to patients with hypertension alone (P < 0.05). In addition, the MS patients combining with hypertension showed a lower E/A (MD = -0.07, 95 % CI: -0.10 to -0.04) when compared to those with hypertension alone. This study suggests that MS plays an important role in the development of LVH. MS seems to amplify hypertension-related cardiac changes. Furthermore, MS combining with higher level of BP will aggravate LVH and damage the diastolic function of left ventricle.