Paced QT interval as a risk factor for new-onset left ventricular systolic dysfunction and cardiac death after permanent pacemaker implantation

Background: Prolongation of corrected QT (QTc) interval reflects an increased risk of fatal arrhythmia and cardiac death in various populations. However, it is not clear whether the paced-QTc (p-QTc) interval is associated with new-onset left ventricular systolic dysfunction (new-LVSD) or cardiac death. Methods: In 491 consecutive patients (64 +/- 14 years) with preserved LV ejection fraction (64 +/- 7%), the p-QTc interval was measured within 2 weeks after PPM implantation. We assessed the rates of new-LVSD and cardiac death based on the degree of p-QTc interval. Results: During the follow-up period (78 +/- 51 months), new-LVSD and cardiac death were identified in 53 (10.8%) and 26 (5.3%) patients, respectively. Patients with new-LVSD had more frequent atrioventricular block (P = 0.041), a higher percentage of ventricular pacing (P = 0.005), a longer p-QRS duration (P < 0.001), and more prolonged p-QTc interval (P < 0.001) compared to those without new-LVSD. There was a graded increase in the rates of new-LVSD (P < 0.001) and cardiac death (P = 0.001) from the patients in the lowest to those in the highest tertile of the p-QTc interval. Additionally, the incidence of cardiac death was significantly elevated especially in the patients with new-LVSD and wider p-QTc interval. In Cox regression analyses, the p-QTc interval was independently associated with new-LVSD and cardiac death even after adjusted with various relevant confounding factors. Conclusions: Prolonged p-QTc interval was closely associated with new-LVSD and cardiac death after PPM implantation in patients with preserved LV systolic function. The rate of cardiac death significantly increased especially in patients who showed more p-QTc widening along with new-LVSD. (C) 2015 Elsevier Ireland Ltd. All rights reserved.