Effect of right ventricular pacing on left ventricular systolic function in patients with Tetralogy of Fallot

Background: Prevalence of pacemaker-induced cardiomyopathy (PICM) in adults with congenital heart disease is unknown. Tetralogy of Fallot (TOF) is a common diagnosis in the adult congenital heart disease population, and the purpose of this study was to determine association between frequent right ventricular (RV) pacing and temporal decrease in left ventricular ejection fraction (LVEF) from pre-implantation to 2-years post-implantation (LVEF_post-pre) in TOF patients. Methods: We studied TOF patients that received RV leads only (N = 51) and a reference group of 7 patients with atrial pacing or biventricular pacing. We defined PICM as a ≥10% decrease in LVEF resulting in LVEF <50%. Linear regression was used to assess relationship between frequent RV pacing (≤20%, 21–40%, >40%) and LVEF_post-pre. Results: PICM occurred in 2 (4%) of 51 patients in RV pacing group. LVEF_post-pre was +3% (95% confidence interval [CI] 0% to +5%) in the reference group and −4% (95% CI −11% to +2%) in RV pacing group. No significant difference occured in LVEF_post-pre between the reference group (LVEF_post-pre +3%) vs RV pacing ≤20% (LVEF_post-pre +1%) vs RV pacing 21–40% (LVEF_post-pre −3%) vs RV pacing >40% (LVEF_post-pre −5%), p = 0.318. There was also no association between frequent RV pacing and LVEF_post-pre, R² = 0.307, p = 0.10. Conclusion: PICM occurred in 4% of TOF patients receiving RV pacing, and there was no association between frequent RV pacing and temporal decline in LVEF. Further studies are required to determine the long-term impact of RV pacing in the TOF population, and explore optimal treatment strategies.