History of prior cardiac surgery confers lower risk of pericardial effusion following leadless pacemaker implantation: Insights from a large, real-world dataset

Background Pericardial effusion is a serious complication after implantation of Leadless Pacemaker (LP), with multiple risk factors as possible contributors. In particular, the association between pericardial effusion and prior cardiac surgery has not been well characterized from a large dataset. Methods Using the TriNetX Research Network, we conducted a retrospective observational cohort study of adults (≥18 years) who underwent implantation of LP between January 1, 2010, and July 31, 2025. Patients were stratified by history of prior open cardiac surgery (coronary artery bypass grafting or valve surgery). The primary outcome was pericardial effusion within 30 days of LPI; the secondary outcome was pericardial tamponade. Propensity score matching (1:1) was used to balance demographics, comorbidities, and medication use, with standardized mean differences <0.1 indicating adequate balance. Kaplan–Meier and Cox proportional hazards models were applied to compare outcomes. Results Among 131,607 patients undergoing LPI, 18,379 (14.0%) had prior open cardiac surgery. After 1:1 matching, 18,378 patients remained in each group with well-balanced baseline characteristics. Within 30 days, pericardial effusion occurred in 1.63% of patients with prior cardiac surgery vs. 2.82% without (hazard ratio [HR] 0.57; 95% confidence interval [CI] 0.51–0.66; p<0.0001, Figure 1). Similarly, pericardial tamponade occurred in 0.29% of patients with prior cardiac surgery vs. in 0.52% of patients without history of prior cardiac surgery (HR 0.56; 95% CI 0.40–0.78; p=0.0006, Figure 2). In multivariable Cox analysis, prior open cardiac surgery remained independently associated with reduced risk of pericardial effusion (HR 0.57; 95% CI 0.51–0.66; p<0.0001). Other factors which conferred a higher risk of pericardial effusion and tamponade were: Congestive heart failure, End-stage renal disease, and history of Atrial fibrillation or Atrial flutter. Conclusion In this large multicenter dataset, history of prior cardiac surgery was observed to be independently associated with a reduced incidence of pericardial effusion and tamponade in patients who underwent LP implantation. These findings suggest post-surgical remodeling of the pericardium is protective and support its inclusion into procedural risk stratification and patient selection for LP implantation.