Postoperative pericardial effusion, pericardiotomy, and atrial fibrillation: An explanatory analysis of the PALACS trial

• Published in: The American heart journal Vol. 260; pp. 113 - 123
• Main Authors: Rong, Lisa Q., Di Franco, Antonino, Rahouma, Mohamed, Dimagli, Arnaldo, Chan, June, Lopes, Alexandra J., Kim, Jiwon, Sanna, Tommaso, Devereux, Richard B., Delgado, Victoria, Weinsaft, Jonathan W., Crea, Filippo, Alexander, John H., Gillinov, Marc, DiMaio, John Michael, Pryor, Kane O., Girardi, Leonard, Gaudino, Mario
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01-06-2023; Elsevier Limited
• Subjects: Atrial Fibrillation - epidemiology; Atrial Fibrillation - etiology; Atrial Fibrillation - prevention & control; Cardiac arrhythmia; Cardiac Surgical Procedures - adverse effects; Coronary vessels; Diabetes; Effusion; Ejection fraction; Esophagus; Fibrillation; Heart; Heart surgery; Humans; Hypotheses; Patients; Pericardial Effusion - epidemiology; Pericardial Effusion - etiology; Pericardial Effusion - surgery; Pericardiectomy - adverse effects; Pericardiectomy - methods; Pericardium; Postoperative Complications - epidemiology; Postoperative Complications - prevention & control; Regression analysis; Surgery; Treatment Outcome; Ultrasonic imaging; Veins & arteries; NYHA; POAF; OR; TTE; LA; TEE; CI; ICC; IQR; PALACS; BMI
• ISSN: 0002-8703; 1097-6744
• DOI: 10.1016/j.ahj.2023.03.001

In the Posterior left pericardiotomy for the prevention of atrial fibrillation after cardiac surgery (PALACS) trial, posterior pericardiotomy was associated with a significant reduction in postoperative atrial fibrillation (POAF) after cardiac surgery. We aimed to investigate the mechanisms underlying this effect.
We included PALACS patients with available echocardiographic data (n = 387/420, 92%). We tested the hypotheses that the reduction in POAF with the intervention was associated with 1) a reduction in postoperative pericardial effusion and/or 2) an effect on left atrial size and function. Spline and multivariable logistic regression analyses were used.
Most patients (n = 307, 79%) had postoperative pericardial effusions (anterior 68%, postero-lateral 51.9%). The incidence of postero-lateral effusion was significantly lower in patients undergoing pericardiotomy (37% vs 67%; P < .001). The median size of anterior effusion was comparable between patients with and without POAF (5.0 [IQR 3.0–7.0] vs 5.0 [IQR 3.0–7.5] mm; P = .42), but there was a nonsignificant trend towards larger postero-lateral effusion in the POAF group (5.0 [IQR 3.0–9.0] vs 4.0 [IQR 3.0–6.4] mm; P = .06). There was a non-linear association between postero-lateral effusion and POAF at a cut-off at 10 mm (OR 2.70; 95% CI 1.13, 6.47; P = .03) that was confirmed in multivariable analysis (OR 3.5, 95% CI 1.17, 10.58; P = 0.02). Left atrial dimension and function did not change significantly after posterior pericardiotomy.
Reduction in postero-lateral pericardial effusion is a plausible mechanism for the effect of posterior pericardiotomy in reducing POAF. Measures to reduce postoperative pericardial effusion are a promising approach to prevent POAF.
Pathophysiological mechanisms explaining the association between postoperative pericardial effusion and the occurrence of postoperative atrial fibrillation. Hb, hemoglobin; MetHb, methemoglobin; OxyHb, oxyhemoglobin; ROS, reactive oxygen species. [Display omitted]