Effect of a successful percutaneous coronary intervention for chronic total occlusion on parameters of ventricular repolarization.

BACKGROUND: Coronary collaterals may be insufficient for restoring blood flow to normal levels in patients with chronic total occlusions (CTO), leading to myocardial ischemia and electrical inhomogeneity in the ventricles. We evaluated the effect of percutaneous CTO revascularization on parameters of ventricular repolarization, including the T wave peak-to-end interval (TpTe) interval, the TpTe/QT ratio, and QT dispersion.

PATIENTS AND METHODS: A total of 114 patients who underwent CTO percutaneous coronary intervention (PCI) of any major coronary artery were divided into two groups: the successful CTO PCI group (n=90) and the failed CTO PCI group (n=24). Patients' 12-lead ECGs were analyzed within 24 h before revascularization and 24-48 h after the procedure for the following parameters: corrected QT interval (QTc) dispersion, TpTe interval (V2 and V5), and TpTe/QT ratio (V2 and V5). Subsequently, the successful CTO PCI group was divided into subgroups according to the Rentrop class, number of diseased vessels, and target vessels for further evaluation.

RESULTS: There was no significant difference between the successful and the failed CTO PCI groups in terms of any baseline demographic or angiographic characteristic, or ventricular repolarization parameter. The post-PCI values of TpTe (85.3±12.8 vs. 74.8±10.4; P<0.001), the TpTe/QT ratio (0.21±0.02 vs. 0.19±0.02; P<0.001), and QTc dispersion (65.6±9.8 vs. 53.4±11.6; P<0.001) were significantly decreased compared with the pre-PCI values after successful CTO PCI. The patients in Rentrop class 1 and patients with multivessel disease had higher pre-PCI values for TpTe and the TpTe/QT ratio than those in the other groups (P<0.05). No significant differences were detected when the preprocedure values of TpTe, the TpTe/QT ratio, and QTc dispersion were compared according to the target vessel.

CONCLUSION: In patients with CTO, a poor coronary collateral status and multivessel disease may further impair electrical homogeneity. Our results indicate that successful CTO PCI reduces the arrhythmic vulnerability of the myocardium on the basis of an analysis of the TpTe, the TpTe/QT ratio, and QTc dispersion.