The effect of cardiovascular autonomic neuropathy on resting ECG in type 1 diabetic patients.

BACKGROUND: Cardiovascular autonomic neuropathy (CAN) is a common complication of diabetes mellitus. AIM: To assess the manifestations of CAN on ECG at rest. SUBJECTS AND METHODS: 100 type I diabetic patients, mean age 36.5 (range 17-62) years, mean duration of diabetes 14.6 (range 0-49) years were examined. The control group consisted of 88 healthy subjects, mean age 37 (range 15-65) years. Cardiovascular reflexes (respiration sinus arrhythmia, orthostatic test and Valsalva's maneuvre) were examined, and ECG at rest was analysed. RESULTS: In 35 (35%) diabetics CAN was established. In comparison to diabetic patients without neuropathy, patients with CAN had a higher heart rate (94, 89-99 vs. 79, 75-82 heart beats.min-1, p < 0.001), higher P wave voltage (0.13, 0.12-0.15 vs 0.11, 0.09-0.12 mV, p < 0.001), as well as QTc interval length (422, 410-433 vs 396, 388-404 ms, p < 0.001), but they had a lower voltage of R wave (0.83, 0.72-0.94 vs. 1.0, 0.91-1.09 mV, p < 0.05) and lower T wave voltage (0.18, 0.15-0.21 vs 0.23, 0.19-0.27 mV, p < 0.05). CONCLUSIONS: The higher voltage of P wave, lower voltage of T wave, shorter PQ interval and prolonged QTc interval with tachycardia may be the manifestation of relative sympatheticotonia. Lower R wave voltage and the prolonged QRS complex are the possible signs of cardiomyopathy. (Tab. 4, Ref. 31.)