Relation of systemic blood pressure, left ventricular mass, insulin sensitivity, and coronary artery disease to QT interval duration in nondiabetic and type 2 diabetic subjects

A prolonged QT interval has been identified as a risk factor for cardiovasc ular disease; however, knowledge about etiologic factors is limited. We stu died determinants of QT interval duration in the Insulin Resistance Atheros clerosis Study, a large, triethnic population (n = 1,577) with varying degr ees of glucose tolerance. In particular, we sought to investigate the relat ian of QT interval with blood pressure (BP), left ventricular (LV) mass, es timated using electrocardiographic criteria, and insulin sensitivity, direc tly measured by a frequently sampled intravenous glucose tolerance test. QT interval was measured electronically on electrocardiograms at rest and cor rected for heart rate using standard equations, The QT interval was related to various components of the insulin resistance syndrome, including BP and insulin sensitivity. Multivariate analyses showed that BP and LV mass were the main determinants of the QT interval in diabetic and nondiabetic subje cts. Additionally, prevalent coronary artery disease was related to the QT interval in subjects with newly diagnosed diabetes. In conclusion, we found that BP and LV mass were the strongest and most consistent determinants of the QT interval in nondiabetic and diabetic subjects. Additional factors p otentially contributing to QT interval prolongation in diabetic patients in clude insulin sensitivity and prevalent coronary artery disease. (C) 2000 b y Excerpta Medico, Inc.