PALACS: A Win for Posterior Left Pericardiotomy for Post-Op Afib

Posterior left pericardiotomy during open-heart surgery was linked with a reduction in post-operative atrial fibrillation (Afib), according to results from the PALACS trial.

In the intention-to-treat population, post-op Afib occurred among 17% (n=37/212) patients who underwent pericardiotomy versus 32% (66/208) who were randomized to receive no intervention during their cardiac procedures, reported Mario Gaudino, MD, of New York-Presbyterian/Weill Cornell Medical Center in New York City.

Adjusting for the stratification variable used in the study, the odds ratio was 0.44 (95% CI 0.27-0.70, P=0.0005), while the relative risk was 0.55 (95% CI 0.39-0.78), Gaudino and colleagues reported in the Lancet, and simultaneously at the American Heart Association (AHA) virtual meeting.

Gaudino reported that two patients who had posterior left pericardiotomy, and one patient in the no-intervention group died within 30 days after hospital discharge.

Postoperative major adverse events (AEs) occurred in six patients in the study arm and four in the no-intervention arm, and no posterior left pericardiotomy-related complications were observed, according to Gaudino and colleagues.

“Posterior left pericardiotomy is highly effective in reducing the incidence of atrial fibrillation after surgery on the coronary arteries, aortic valve, or ascending aorta, or a combination of these without additional risk of postoperative complications,” he stated.

However, Gaudino acknowledged PALACS’ limitations, including its single-center setting. Also, patients undergoing mitral and tricuspid valve surgery were excluded because of different post-op Afib risk from other cardiac procedures. Finally, PALACS was not powered for clinical events.

Laurence Epstein, MD, of Northwell Health Sandra Atlas Bass Heart Hospital in Manhasset, New York, called the study “very interesting,” but advised some caution when interpreting the results.

“This is a very selected population, and of the 420 patients in the study, 333 of the procedures were performed by one surgeon,” noted Epstein, who was not involved in PALACS. “We do need — as the authors themselves say — a much larger population, across a wider spectrum of cardiac surgery, for this procedure to change clinical practice.”

He explained that by performing the pericardiotomy during heart surgery, blood that would accumulate in the tight pericardia drains into the larger pleural cavity. The effusion can irritate the heart muscle and disrupt the electrical activity of the heart, often causing Afib. The effusion into the pleural cavity doesn’t cause the same type of problem because there is little electrical activity with the lungs, Epstein told MedPage Today.

Gaudino’s group wrote that “Atrial fibrillation is the most common complication after cardiac surgery and is associated with extended in-hospital stay and increased adverse outcomes, including death and stroke,” so they “tested the hypothesis that posterior left pericardiotomy, a surgical maneuver that drains the pericardial space into the left pleural cavity, might reduce the incidence of atrial fibrillation after cardiac surgery.”

The trial ran from September 2017 to August 2021 and enrolled randomizing 420 patients (median age 61; 76% male; 21% with diabetes) with no history of Afib or other arrhythmias. They received either posterior left pericardiotomy or no intervention. Patients undergoing mitral and tricuspid surgery and reoperations were excluded.

Patients were stratified by CHA2DS2-VASc score (median score 2) with a mixed-block randomization (block sizes of four, six, and eight). Patients and assessors were blinded to treatment assignment. Both arms received routine post-op Afib prophylaxis. Duration of follow-up was a median 6 days.

The researchers reported that post-op pericardial effusion was lower in the left pericardiotomy group at 12% versus 21% in the no-intervention group (RR 0.58, 95% CI 0.37-0.91).

While surgery time was higher in the study group versus the no-intervention group (median 306 minutes vs 289 minutes), the median post-op hospitalization was basically the same at 6 days for both arms, according to Gaudino.

In a Lancet accompanying comment, Jolanda Kluin, MD, PhD, of the University of Amsterdam, and colleagues pointed out that “this simple surgical procedure reduces the risk of cardiac tamponade, [and] a randomised comparison between posterior left pericardiotomy and standard of care, with postoperative atrial fibrillation as a primary outcome measure, had not been performed until now.” PALACS fills “this knowledge gap,” they stated.

In an American College of Cardiology summary article, Anthony A. Bavry, MD, MPH, of UT Southwestern Medical Center in Dallas, wrote that the “trial was adequately powered for a single-center study. A large confirmatory multicenter trial is needed to quantify potential clinical benefits from this intervention.”