Table 2.

Recent and major studies of the incidence of electrocardiographic abnormalities in cardiac autonomic neuropathy.

Reference	Population/Animals	ECG marker	Clinical significance	Clinical points
Classical ECG markers in CAN and diabetes
[73]	Zucker Diabetic Fatty rats	↑ R wave amplitude, ↑ QT intervals,↓ HRV	Early diagnosis of CAN, Diabetic Cardiomyopathy	Beneficial effect of aerobic exercise in R wave amplitude
[74]	682 T2D + coronary heart disease	↑ QTc	↑ risk for sudden cardiac death	Idiopathic QT prolongation:5-fold ↑ risk of SCD
[75]	1.226 T1D patients	↓ QTc	↓ incidence of CAN with intensive diabetic treatment	14 years follow-up endpoint
[76]	18 healthy subjects, 30–40 years	↓ PR, ↑ QTc, ↓ T-wave amplitude, ↓ ST	Early diagnosis of CAN, Arrhythmia	severe arrhythmias and “dead-in-bed” syndrome in unrecognized hypoglycemia
[77]	1.720 T2D patients + healthy	QTc > 440 msec, ↓ HRV	↑ mortality	↑ QT dispersion not significant predictor
[78]	100 T1D and T2D patients	↑ QTc	CAN	Association with age, diabetes duration, severity of CAN
[79]	192 T2D patients	↑ QTc, ↑ QT dispersion	12-y CVD risk	Superior to ABI, CAN test for CVD risk
[80]	80 T1D patients	↑ QTc	CAN	Absence of ventricular late potentials in QTc
[81]	8.185 healthy people	↓ HRV and ↑ Heart Rate > 73 bpm	60% ↑ risk of T2D	Independent of CVD disease, age, gender, life and style
[82]	105 T1D and T2D patients	↑ QTc > 440 msec	↑ CAN severity (Ewing score)	Association with age, obesity, hypertension, diabetes duration and control, diabetic treatment
[83]	26 males with diabetes	↑ QTc	↑ 3-year SCD risk in CAN	Independent of age, diabetes duration
Vectorcardiography: the alternative proposition in CAN and diabetes
[84]	5.781, age ≥ 55 years, 12.7% with diabetes	Spatial QRS-T angle ≥ 75°	4-fold ↑ risk of 4-year CVD and SCD	3-fold ↑ risk of fatal and nonfatal CVD events
[85]	4.173, 14% with diabetes	Spatial QRS-T angle ≥ 45°	50%↑ risk of 7-year incident CVD	50%↑ risk of 7-year total mortality
[56]	6.134, 10% with diabetes	Spatial QRS-T angle ≥ 105°	5-fold ↑ risk of CVD death	2-fold ↑ risk of SCD and total mortality
[86]	142 women, 32% with diabetes	Spatial QRS-T angle ≥ 49°	1.5-fold ↑ risk of CVD events	3-year prospective study
[3]	232 T2D patients	↑ spatial QRS-T angle	↑ incidence of CAN ↑ incidence of Diabetic Cardiomyopathy	Association with HRV (↓parasympathetic tone and ↑ sympathetic tone or sympathovagal imbalance)

CAN: cardiac autonomic neuropathy; T2D: type 2 diabetes; T1D: type 1 diabetes; HRV: heart rate variability; QTc: QT interval corrected for heart rate; SCD: sudden cardiac death; CVD: cardiovascular disease; ABI: ankle-brachialindex.