Response to letter re: ‘Premature Ventricular Complexes after Catheter Ablation for Atrial Fibrillation: Accounting For Regression to the Mean’William Whang, MD1 and Alex Choy, MD21Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, NY; [email protected] of Medicine, University of Chicago, Chicago, IL; [email protected] author: William Whang, MD ([email protected])One Gustave Levy PlaceNew York, NY 10029212-241-7114We thank Dr. Wang for his interest in our research letter. He questions whether the endpoint used in our study, frequency of premature ventricular complexes (PVC) as a percentage of total complexes measured pre- versus post-ablation, is a valid indicator due to the skewed distribution and lack of granularity. Although we did not use absolute number of PVCs per day from a 24-hour Holter for our endpoint, we would argue that PVC percentage is a valid indicator of arrhythmia burden that has been associated in a dose-dependent manner with outcomes such as cardiomyopathy and mortality in cohorts such as the community-based Cardiovascular Health Study.1 In addition, in our study the median duration of monitoring (6 days) was longer than in prior studies of atrial fibrillation (AF) ablation and PVCs. A recent study that used commercially available event monitors concluded that longer monitoring periods resulted in significantly reduced mean measured error of PVC burden.2We sought to approach the measure for significant PVC burden (≥1000/day) mentioned by Dr. Wang, with a proxy threshold of ≥1% PVCs. In our sample 21.5% of patients had ≥1% PVCs pre-ablation and 19.2% had ≥1% PVCs post-ablation (p=0.76, chi-squared test), again suggesting lack of significant association between AF ablation and PVC burden. We agree with Dr. Wang that prospective studies would be worthwhile to assess the true impact of AF ablation on PVCs, and would stress that inclusion of samples unrestricted by PVC burden pre-ablation could help clarify this question.1. Dukes JW, Dewland TA, Vittinghoff E, Mandyam MC, Heckbert SR, Siscovick DS, Stein PK, Psaty BM, Sotoodehnia N, Gottdiener JS, Marcus GM. Ventricular Ectopy as a Predictor of Heart Failure and Death.Journal of the American College of Cardiology . 2015;66:101–109. 2. Krumerman A, Di Biase L, Gerstenfeld E, Dickfeld T, Verma N, Liberman L, Amara R, Kacorri A, Crosson L, Wilk A, Ferrick KJ. Premature ventricular complexes: Assessing burden density in a large national cohort to better define optimal ECG monitoring duration. Heart Rhythm . 2024;21:1289–1295.