Cardiac autonomic function in metabolic syndrome: a comparison of ethnic Turkish and Japanese patients

Metabolic syndrome (MetS) prevalence shows some differences at various regions of the world in terms of race and ethnicity. The cardiac autonomic functions between Turkish and Japanese MetS patients with heart rate turbulence (HRT) and heart rate variability (HRV) were compared as the aim of this study.

This study consists of 149 nondiabetic subjects with MetS. All patients were further classified into subgroups based on ethnicity (76 from Turkey, 73 from Japan). Twenty-four-hour ambulatory Holter ECG recording was applied to all subjects whose HRV and HRT (total onset (TO), total slope (TS)) parameters were analyzed.

The waist circumference was the only demographic parameter that was significantly different between the Turkish and Japanese patients with MetS (99.31 ± 6.12 vs 91.12 ± 6.89 for men and 91.48 ± 7.45 vs 86.26 ± 5.78 for woman; p < 0.001 and <0.001). There was a significant difference between Turkish and Japanese patients with MetS in terms of the HRT values. (TO Turkish, 0.77 ± 0.19 %; TO Japanese, 0.49 ± 1.03 %, p = 0.031; TS Turkish, 1.93 ± 1.26; TS Japanese, 2.44 ± 1.37, p = 0.041, respectively). As for HRV parameters, standard deviation of all NN intervals index was only different between Turkish and Japanese patients with MetS (90.79 ± 58.94, 128.18 ± 105.30; p = 0.034, respectively).

HRT and some HRV scores of ethnic Turkish MetS patients are worse than the scores of ethnic Japan MetS patients. We think that these differences are related to the central obesity.