Abstract Body (Do not enter title and authors here): Background: Papillary Muscle (PM) related ventricular arrhythmia ablation is associated with lower acute success and suboptimal long-term outcomes due to complex anatomy, variable arrhythmogenic sites and dynamic exit points.

Objective: To evaluate clinical and procedural outcomes of patients undergoing PM vs non-PM ablation.

Methods: A retrospective analysis of adults (≥18 years) undergoing PVC ablation at Mayo Clinic (2019–2024) matched PM PVC ablations to controls (1:2) using propensity scoring based on age, sex, comorbidities and baseline LVEF. Chi-square and t-tests compared baseline and procedural characteristics. Logistic regression estimated odds ratios for immediate procedural success, PVC burden reduction and LVEF improvement at 3 months.

Results: Of the 720 ablations, 392 cases were included after propensity matching: 132 PM and 260 non-PM. Patients in the PM group exhibited higher rates of complicated diabetes (9.8% vs 4.6%, p=0.045) and prior MI (18.2% vs 9.2%, p=0.011). Preprocedural ECG PVCs in the PM group showed a shorter intrinsicoid deflection (89.1 ± 35.0 msec vs 100.7 ± 24.3 msec, p<0.001) and longer coupling intervals (532.7 ± 100.3 vs 512.2 ± 81.4 msec, p=0.048).Moderate-to-severe MR was more prevalent in the PM group (17.4% vs 10.0%, p=0.036). Intraoperatively, the PM group had higher total energy delivery times (1939 ± 1336 sec vs 1227 ± 1033 sec, p<0.001) and more frequent cryoablation use (46.2% vs 7.3%, p<0.001). During post-ablation testing, non-clinical PVC was inducible in 39.5% of the cases in PM group compared to 25.7% in non-PM group (p=0.005). More patients in the PM group were discharged on atleast one antiarrhythmic drug (AAD)(35.9% vs 18.5%, p<0.001) and AAD use persisted at 3 months (31.3% vs 18.4%, p=0.004). Outcomes were similar between groups, with no significant differences observed in immediate ablation success (aOR 0.64, p = 0.063, CI = 0.40-1.03), or >5% improvement in LVEF (aOR 0.76, p = 0.29) and PVC burden reduction (aOR 0.93, p = 0.81) at 3 months follow up.

Conclusion: Patients undergoing PM ablation exhibited higher baseline rates of comorbidities. Intraoperatively they required greater energy delivery times, and an increased use of cryoablation. Postoperatively, a larger proportion of PM ablation patients required antiarrhythmic drug therapy. Despite these complexities, PM ablation showed no significant differences in PVC burden reduction, LVEF improvement, or procedural success compared to non-PM ablation.