RESUMO
The purpose of this study was to assess the abnormalities and prevalence of QT dispersion in 154 diabetic patients (DP) who underwent a standard 12-lead ECG. QT interval was measured from the beginning of the QRS complex until the T wave returned to baseline. Atrial fibrillation, pacemakers and the impossibility of measuring 6 QT intervals per ECG were reasons for exclusion from the study. Diabetic patients were compared with 104 sex- and age-matched controls (C): mean age 50.7 +/- 2.3 years (DP) vs 48.4 +/- 10.1 (C) (ns); diabetes duration: 11.6 +/- 7.9 years. Seventy-eight percent of DP were non-insulin-dependent. Mean QT duration was 0.383 +/- 0.031 s (DP) vs 0.381 +/- 0.026 (C) (ns); QT dispersion (difference between the longest and shortest QT interval measurement) 0.033 +/- 0.015 s (DP) vs 0.024 +/- 0.011 (C) (p < 0.001); and QT variability 3.003 +/- 1.23% (DP) vs 2.295 +/- 0.936 (C) (p < 0.001); with a standard deviation of 0.012 +/- 0.005 s (DP) vs 0.009 +/- 0.004 (C) (ns). QT dispersion indices (dispersion, variability) were significantly increased in DP, even for short diabetes duration. Future studies should focus on QT dispersion to assess the usefulness of such indices in detecting DP at high risk of sudden death and ventricular arrhythmias.
