Background: Diabetic retinopathy (DR) is strongly associated with cardiovascular disease, which is a risk factor for sudden cardiac death (SCD). The index of cardiac electrophysiological balance (iCEB) and the frontal QRS-T angle are recommended to predict the risk of ventricular arrhythmias more than other ECG parameters. However, the relationships between these two markers and DR have not yet been explored. The aim of this study was to investigate the variation in the iCEB, corrected iCEB (iCEBc) and frontal QRS-T angle in different stages of DR and determine whether there are associations between these markers and DR.
Methods: The sample comprised 665 patients with Type 2 diabetes mellitus (T2DM) who were classified into three groups: no DR (NDR), mild to moderate non-proliferative DR (NPDR), and vision-threatening DR (VTDR). Twelve-lead ECG was performed and the QT, QTc, QRS duration, iCEB, iCEBc and frontal QRS-T angle were recorded and compared across the groups.
Results: The VTDR group had a significantly higher iCEBc and frontal QRS-T angle than the NDR and NPDR groups. After controlling for confounding variables, the correlations between the iCEBc (OR=2.217, 95% CI=1.464– 3.358, P< 0.001), frontal QRS-T angle (OR=1.017, 95% CI=1.008– 1.025, P< 0.001) and DR risk remained (P< 0.05). Subjects in the fourth iCEBc quartile (adjusted OR=2.612, 95% CI=1.411– 4.834, p=0.002) had a much higher chance of developing DR compared to those in the first quartile. In comparison to the first frontal QRS-T angle quartile, subjects in the third (adjusted OR=1.998, 95% CI=1.167– 3.422, P=0.012) and fourth (adjusted OR=2.430, 95% CI=1.420– 4.160, P=0.001) frontal QRS-T angle quartiles had significantly greater risks of DR.
Conclusion: With the progression of DR, the iCEBc and frontal QRS-T angle increase. An increased iCEBc and frontal QRS-T angle are associated with an increased risk of DR.
Keywords: type 2 diabetes mellitus, diabetic retinopathy, index of cardiac electrophysiological balance, iCEB, frontal QRS-T angle, ventricular arrhythmia