Clinical determinants of increased QT dispersion in patients with diabetesmellitus

Aims: To compare QT dispersion measurements in diabetic patients to control subjects and assess any associations between QT dispersion and diabetic cl inical characteristics. Methods: A total of 512 diabetics and 50 age and ge nder matched controls were studied. QT interval was measured manually in 12 -lead conventional electrocardiograms, and QT dispersion (QTd), heart rate- corrected QT dispersion (QTcd), number of leads-adjusted QT dispersion (adj uQTd) and adjacent QT dispersion (adjaQTd) were calculated. Demographic, cl inical, laboratory and electrocardiographic data were recorded. Results: Di abetics showed increased QT dispersion compared to controls (QTd: P <0.001, QTcd: P <0.001, adjuQTd: P <0.001), even those with recent diagnosis (less than 2 years) and without arterial hypertension, ECG abnormalities or chro nic degenerative complications (QTd: P=0.01, QTcd: P <0.001, adjuQTd: P=0.0 4). Left ventricular hypertrophy (QTd: P <0.001, QTcd: P <0.001, adjuQTd: P <0.001, adjaQTd: P <0.001) and conduction disturbances (QTd: P=0.002, QTcd : P=0.003, adjuQTd: P=0.003) were the electrocardiographic findings associa ted with increased QT dispersion in bivariate analysis. Clinical variables were the presence of arterial hypertension (QTd: P=0.004, QTcd: P=0.01, adj uQTd: P<0.001), even without left ventricular hypertrophy (QTd: P=0.01, QTc d: P=0.03, adjuQTd: P=0.003), and the presence of diabetic cardiovascular c omplications (QTd: P=0.02, QTcd: P=0.01, adjuQTd: P=0.008, adjaQTd: P=0.03) . No association between QT dispersion and the presence of diabetic microva scular complications, glycaemic control, age and gender, or cardiovascular drugs was observed. Multivariate regressive statistical analysis confirmed the associations noted in bivariate analysis. Conclusions: Diabetic patient s have increased QT dispersion compared to non-diabetics even those without arterial hypertension and cardiovascular complications and with recent dia gnosis. The presence of arterial hypertension, diabetic cardiovascular comp lications and electrocardiographic abnormalities of left ventricular hypert rophy and conduction disturbances were associated to increased QT dispersio n in diabetes mellitus. <(c)> 2001 Elsevier Science Ireland Ltd. All rights reserved.