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Arch Hellen Med, 27(3), May-June 2010, 475-486


Assessment of the risk of arrhythmia in subjects with type 2 diabetes
and cardiac autonomic neuropathy, using the spatial QRS-T angle

1First Department of Propedeutic Internal Medicine, "Laiko" General Hospital, Medical School, National and Kapodistrian University of Athens, Athens,
Department of Cardiology, "Laiko" General Hospital, Athens,
3Laboratory of Experimental Surgery and Surgical Research, "Laiko" General Hospital, Medical School, University of Athens, Athens, Greece

OBJECTIVE Cardiac autonomic neuropathy (CAN) is a common complication of type 2 diabetes (T2DM) and it has been associated with repolarization abnormalities of the left ventricle (LV), diabetic cardiomyopathy, silent myocardial ischemia and a high cardiovascular mortality. Using classical electrocardiographic parameters for the assessment of LV electrical activity, namely the QT interval and its dispersion, studies on the association between the QT interval and CAN have had conflicting findings. The spatial QRS-T angle (spQRS-Ta) is a new reliable marker of arrhythmia which better assesses depolarization and repolarization abnormalities of the LV; higher values of spQRS-Ta predict cardiovascular events and mortality, both in the general population and in high-risk subjects. The purpose of the present study was to examine differences in the spQRS-Ta in subjects with T2DM with and without CAN.

METHOD A total of 232 subjects with T2DM (105 with CAN and 127 without CAN) (mean age 58.4±9.1 years) and 232 healthy control subjects, matched for age and gender with the study population, were investigated. The diagnosis of CAN was based on the classical autonomic function tests. All subjects underwent a digital 15 min ECG and 30 min heart rate recordings. ECG parameters were measured using the MEANS program. Indices of the heart rate variability (HRV) were obtained using the VariaCardio system. Ankle-brachial-pressure index, LV mass index and the global myocardial performance index (Tei index) were assessed by ultrasonography (US).

RESULTS The spQRS-Ta was higher in the subjects with T2DM than in the control subjects (24.5±10.7° vs 9.7±4.5°, p<0.001) and in the subjects with CAN than in those without CAN (30.1±11.3° vs 19.5±7.1°, p<0.001). No differences were found in the QT interval or its dispersion between the studied groups. Multivariate linear regression analysis in the subjects with T2DM demonstrated an independent association between the spQRS-Ta and the presence and the severity of CAN, HbA1c, the duration of diabetes, HOMA-IR, lipids, microalbuminuria, LV mass index, Tei index, and parameters of the HRV.

CONCLUSIONS The spQRS-Ta is increased in patients with T2DM who have CAN, suggesting an increased risk of arrhythmia. An increase in spQRS-Ta values warrants consideration of risk stratification, introduction of prevention strategies and intensification of treatment in subjects with T2DM, aimed at reduction of the increased cardiovascular risk in these patients.

Key words: Cardiac autonomic neuropathy, Electrocardiography, Risk of arrhythmia, Type 2 diabetes, Vectorcardiography.

© Archives of Hellenic Medicine