• Posterior Left Pericardiotomy ‘Highly Effective’ at POAF Reduction Post-Cardiac Surgery: PALACS Trial

    Posterior left pericardiotomy is “highly effective” at reducing postoperative atrial fibrillation (POAF) after cardiac surgery, according to the PALACS trial.

    The new findings were reported Sunday at the American Heart Association (AHA) Scientific Sessions 2021 virtual meeting by lead author Mario F. Gaudino, MD, of Weill Cornell Medicine, New York, and published simultaneously online in The Lancet.

    POAF is the most common complication following cardiac surgery and is associated with lengthier hospital stays and adverse outcomes including death and stroke, the researchers noted in the manuscript.

    Pericardial effusion – which is reported in over two-thirds of patients after cardiac surgery – and retained clots in the pericardium may trigger POAF, they added. Evidence suggests that even small amounts of pericardial effusion can trigger atrial arrhythmias via local inflammation and oxidative damage, they said.

    It has, therefore, long been suggested that posterior left pericardiotomy – a simple surgical maneuver that drains the pericardial space into the left pleural cavity – could reduce POAF incidence; however, “this has never been formally tested,” the researchers said.

    The current study, therefore, set out to test whether posterior left pericardiotomy could reduce POAF in adult patients undergoing elective cardiac surgery, monitoring POAF through continuous cardiac rhythm monitoring during patients’ entire postoperative in-hospital stay.

    The single-center trial ran at Weill Cornell Medicine at the New York Presbyterian Hospital, randomizing 420 patients between September 2017 and August 2021 with no history of atrial fibrillation or other arrhythmias to receive either posterior left pericardiotomy (212 patients) or no intervention (208 patients). The study population included adult patients undergoing elective interventions on the coronary arteries, aortic valve or ascending aorta who had no history of atrial fibrillation or other arrhythmias. Patients undergoing mitral and tricuspid surgery and reoperations were excluded.

    Patients were stratified by CHA2DS2-VASc score and using a mixed-block randomization approach (block sizes of 4, 6, and 8), and both patients and assessors were blinded to treatment assignment. Both arms received routine POAF prophylaxis.

    The patients’ median age was 61 years, the majority (318, 76%) were male, and the median CHA2DS2-VASc score was 2 (interquartile range [IQR]: 1 – 3). The two groups were balanced in clinical and surgical characteristics, the researchers said.

    POAF rates were significantly lower in those receiving posterior left pericardiotomy than in those without intervention, occurring for 37 patients (17%) and 66 patients (32%), respectively (p=0.0007 overall). Adjusting for the stratification variable, the odds ratio was 0.44 (95% confidence interval [CI]: 0.27 – 0.70; p=0.0005), while the relative risk was 0.55 (95% CI: 0.39-0.78).

    Post-operatively, pericardial effusion was also lower in the left pericardiotomy group at 26 patients (12%) versus 45 patients (21%) in the control group (relative risk 0.58; 95% CI: 0.37 – 0.91).

    Surgery time was higher in the treatment group at a median of 306 minutes (IQR 262.5-366.5 minutes), compared to 289 minutes (IQR 252.3-353.5 minutes) in control, although median postoperative hospitalization was even at 6 days for both groups, according to Gaudino’s slides.

    Two patients (1%) died in the posterior left pericardiotomy group at 30 days, versus 1 patient (<1%) in the no-intervention group. Postoperative major adverse events occurred in 6 (3%) in the treatment group versus 4 (2%) in control.

    No posterior left pericardiotomy-related complications were seen.

    “Based on the concordance between the previous evidence and our results, the large treatment effect, and the very favourable risk to benefit ratio of the intervention, posterior left pericardiotomy should be considered during most cardiac surgery operations,” the researchers said in the manuscript.

    They added that posterior left pericardiotomy “seems to have higher efficacy, fewer side-effects, and lower costs” than other available preventative interventions for POAF, including prophylactic administration of beta blockers, amiodarone, colchicine, steroids, magnesium, statins, and postoperative overdrive atrial pacing, “although formal head-to-head comparisons have not been performed.”

    Nevertheless, Gaudino stressed the limitations of the current study, including that it is a single-center trial, that patients undergoing mitral and tricuspid valve surgery were excluded – because of different POAF risk from other cardiac procedures – and that the trial was not powered for clinical events.

    In the manuscript, the researchers went on to call for a large, pragmatic, confirmatory multicenter trial “including the entire spectrum of cardiac surgery operations” to quantify the potential clinical benefits of the intervention.


    Gaudino M, Sanna T, Ballman KV, et al. Posterior left pericardiotomy for the prevention of atrial fibrillation after cardiac surgery: an adaptive, single-centre, single-blind, randomised, controlled trial. Lancet 2021 Nov 14. DOI: 10.1016/S0140-6736. [Article in press]

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