Association of left posterior pericardiotomy with postoperative atrial fibrillation in Isolated OPCAB: a propensity-weighted analysis.

BACKGROUND: Off-pump coronary artery bypass grafting (OPCAB) minimizes systemic inflammation associated with cardiopulmonary bypass, yet postoperative atrial fibrillation (POAF) incidence remains substantial. This suggests that local pericardial factors may contribute significantly to POAF in this setting. We evaluated the impact of left posterior pericardiotomy (LPP) on POAF and drainage patterns in isolated OPCAB to determine if enhancing local drainage effectively mitigates POAF. METHODS: We retrospectively analyzed 283 patients (mean age 65.1 ± 10.2 years; female, 18.7%) undergoing elective isolated multivessel OPCAB by a single surgeon (2021-2025). Patients were categorized into LPP (n = 122, routinely performed since April 2024) and no-LPP (n = 161) groups. Inverse probability of treatment weighting (IPTW) was applied to adjust for baseline differences. The primary endpoint was in-hospital POAF. Postoperative chest tube drainage distribution and incidence of postoperative pericardial effusion were analyzed to assess the mechanistic efficacy of LPP. RESULTS: After IPTW adjustment, the LPP group showed a significantly lower incidence of POAF (15.1% vs. 30.7%; p = 0.003) and shorter hospital length of stay (p = 0.032). Operative time was significantly shorter in the LPP group (334 ± 44 vs. 349 ± 48 min; p = 0.006), suggesting that LPP did not prolong the procedure. Operative mortality and LPP-related complications were absent. Postoperative pericardial effusion was also less frequent in the LPP group (3.2% vs. 8.4%; p = 0.084). Mechanistically, the LPP group demonstrated a significantly higher left-to-total drainage ratio in the early postoperative period, indicating effective diversion of pericardial fluid to the left pleural space during the critical early postoperative period. CONCLUSIONS: In elective isolated OPCAB, concomitant LPP was associated with a lower incidence of POAF and shorter hospital length of stay without increasing operative time or complications. The observed shift in drainage distribution supports the mechanism that LPP reduces POAF by effectively mitigating local pericardial fluid retention.