Patients with Metabolic Syndrome Have Prolonged Corrected QT Interval (QTc)

Abstract

Background: Prolongation of corrected QT interval (QTc) increases morbidity and mortality and QTc has been found to be longer in patients with diabetes mellitus than in healthy controls. It is still inconclusive whether the metabolic syndrome results in QTc prolongation. Hypothesis: We hypothesized that metabolic syndrome might contribute to risk of QTc prolongation. The hypothesis was tested in a large population. Methods: A total of 5,815 individuals (men: 1,950, women: 3,865 aged 20-80 years) were enrolled. Metabolic syndrome was defined according to the revised third NationalCholesterol Education Program Adult Treatment Panel (NCEP-ATP III). QTc was calculated by using Bazett and Fridericia equations and the corrected JT interval (JTc) was derived by subtracting the QRS duration from the QTcB. All individuals had physical examinations, electrocardiograms, echocardiography, and blood tests. Results: Individuals with metabolic syndrome had longer QTcs and JTc than those without metabolic syndrome (439.84 ms versus 430.90 ms in men, 456.37 ms versus 445.12 ms in women, respectively, p < 0.001 using Bazett formula). The more the number of abnormal metabolic parameters they had, the longer the QTcs and JTc they had. Trend analysis indicated that QTcB, QTcF , and JTc were significantly correlated to the number of abnormal metabolic parameters both in men and in women. After being adjusted for conventional risk factors, QTcB, QTcF , and JTc remained negatively associated with serum potassium concentration and positively associated with interventricular septal thickness. Conclusions: Metabolic syndrome is a risk factor for prolonged QTc, which may further increase cardiovascular morbidity and mortality in the subjects with metabolic syndrome.

Risk of Mortality Associated With QT and JT Intervals at Different Levels of QRS Duration (from the Third National Health and Nutrition Examination Survey)

“…QT interval prolongation has been shown to be an independent predictor of mortality in different populations 9–12 , in patients with metabolic syndrome 13 , end stage renal disease 14 and as a predictor of sudden cardiac death in patients with left ventricular hypertrophy 15 and myocardial infarction 16 . Another study evaluated 11,739 subjects with normal conduction and 1,251 subjects with ventricular conduction defects 17 .…”

QT Intervals in Patients Receiving a Renal Transplant

“…A prolonged QT interval has been found to be associated with electrical instability of the myocardium and leads to adverse cardiovascular outcomes, including ventricular fibrillation and sudden death. 17,18 Preclinical evaluation of delayed ventricular repolarization, manifested as a prolonged QT interval, reflects the electrical instability of the myocardium. It is routinely used as an indicator of potential risk of proarrhythmia, such as impending torsades de pointes, ventricular fibrillation, and sudden death.…”

“…19,20 The cardiovascular complication rate is increased in high-risk patients with prolonged QT intervals. 17 QTd, as a noninvasive method, is a marker of myocardial electrical instability and a predictor of arrhythmic events. It seems to reflect the autonomic regulation of cardiovascular function, with increased QTd reflecting higher sympathetic and lower parasympathetic inputs to the heart.…”

Corrected Qt interval in patients with metabolic syndrome

“…[24][25][26] An association between QTc interval and the cardiometabolic syndrome has recently been reported by four separate studies. [27][28][29][30] In this study, the MS was correlated with increasing QTc interval length. This is one of the rare study showing a correlation between MS and QTc interval length.…”