Although obesity and the metabolic syndrome (MS) often co-occur, many obese (OB) subjects have a favorable metabolic profile. It is unclear whether these factors independently influence cardiac electrophysiology including prolongation of the QT interval. We examined associations among obesity, MS, and prolonged corrected QT (QTc) interval in a large sample of Chinese research participants aged ≥35 years recruited from rural areas of Liaoning Province during 2012 to 2013. Of the 11,209 participants, 6,364 (56.8%) were nonobese and metabolically healthy (OB-/MS-), 2,853 (25.5%) were OB-/MS+, 493 (4.4%) were OB+/MS-, and 1,499 (13.4%) were OB+/MS+. Mean (±SD) QTc intervals were higher in OB-/MS+ (436.3 ± 24.3) and OB+/MS+ (436.6 ± 25.9) participants but not OB+/MS- participants (425.4 ± 24.0) than in OB-/MS- participants (426.8 ± 21.5, p <0.001), and the prevalence of QTc prolongation was higher in OB-/MS+ and OB+/MS+ participants (adjusted odds ratios [aOR] 1.68, 95% confidence interval [CI] 1.52 to 1.85; aOR 1.92, 95% CI 1.69 to 2.17, respectively) compared with OB-/MS- group but not in OB+/MS- participants (aOR 0.92, 95% CI 0.73 to 1.15). Prevalence increased with each MS component (aOR 1.27, 95% CI 1.22 to 1.32) but not with body mass index (aOR 1.01, 95% CI 0.99 to 1.02). In conclusion, prolonged QTc interval is associated with the MS and not independently associated with obesity.
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