Introduction: Sympathetic overactivity plays an important role in the development of resistant hypertension (RH). However, the effect of sympathetic predominance on left ventricular hypertrophy (LVH) in RH is not very clear. In our study, we aimed to evaluate the association between sympathetic overactivity and LVH in RH.
Methods: One hundred forty-two RH patients were enrolled in this study. Transthoracic echocardiography was performed in each case and LVH parameters (interventricular septum and posterior wall thickness, left ventricular mass and left ventricular mass index) were assessed. Seventy-five patients had echocardiographic evidence of LVH (RH/LVH(+)) while the other 67 patients did not (RH/LVH(-)). Mean heart rate and time domain heart rate variability (HRV) values - standard deviation of NN intervals (SDNN), standard deviation of all five-minute NN intervals (SDANN), triangular index - that reflect sympathetic overactivity were obtained from 24-hour ECG recordings. Mean heart rate and HRV values were compared between the two groups.
Results: Demographic and clinical characteristics and blood pressure levels were similar between the groups. Echocardiographic parameters that reflect LVH were significantly higher in the RH/LVH(+) group than in the RH/LVH(-) group. Time domain HRV values were significantly lower (SDNN: 119.1 ± 34.6 vs. 138.1 ± 42.9, p=0.004; SDANN: 108.1 ± 41.6 vs. 127.9 ± 45.1, p=0.007; triangular index: 31.2 ± 10.5 vs. 36.3 ± 11.1, p=0.006) and mean heart rate was significantly higher (83.7 ± 16.4 vs. 78.3 ± 12.4, p=0.03) in the RH/LVH(+) group than in the RH/LVH(-) group.
Conclusions: Our study showed that, among patients with RH, sympathetic overactivity is significantly higher in those with LVH.