PALACS

 

Posterior left pericardiotomy for the prevention of atrial fibrillation after cardiac surgery

Mario Gaudino, The Lancet Dec 4 2021; 398: 2075–83 https://doi.org/10.1016/S0140-6736(21)02490-9

Clinical Question

  • In selected patients undergoing cardiac surgery, does posterior left pericardiotomy compared with usual care, reduce the incidence of postoperative atrial fibrillation?

Background

  • Atrial fibrillation is common following cardiac surgery with approximately one-third of patients developing new atrial fibrillation in the immediate postoperative period
  • Pericardial effusion is common following cardiac surgery with approximately two-thirds of patients having evidence of effusion on echocardiography
  • Pericardial effusion can cause inflammatory changes in the myocardium which can result in atrial arrhythmias
  • Posterior left pericardiotomy allows drainage of the pericardial space into the left pleural space, reducing postoperative pericardial effusions
  • Previous small studies, with poor and inconsistent methodology, have suggested pericardiotomy reduces the incidence of atrial fibrillation
  • This trial aimed to provide quality evidence to guide operative management in these at risk patients

Design

  • Single centre, RCT
  • 1:1 randomisation stratified by CHA2DS2-VASc score 
  • Variable block randomisation with computer generated allocation to group
  • Blinding of patient and assessor
  • Surgical team were made aware of the allocation the night prior to surgery
  • Intention to treat analysis
  • A priori publication of study protocol
  • Logistic regression analysis took into account the operating surgeon and other variables such as age, sex, diabetes, LVEF, extent of coronary disease, chronic lung disease, perioperative beta-blocker use
  • Sample size of 350 patients initially calculated to provide 90% power to detect a 50% reduction in primary outcome, based on previous literature and accounting for protocol violations/study dropout (presuming primary outcome incidence of 30%)
  • Sample size increased to 420 after second interim analysis, due to lower than anticipated incidence in primary outcome

Setting

  • Patients treated at the New York Presbyterian Hospital, NY, USA
  • Trial recruitment September 2017 to August 2021
  • Protocol amendment in March 2020 to allow recruitment during COVID-19 pandemic

Population

  • Inclusion:
    • Adults undergoing cardiac surgery
    • Cardiac surgery included coronary surgery, aortic valve surgery or aortic surgery (or a combination of these)
  • Exclusion:
    • Previous history of atrial fibrillation or arrhythmias
    • Patients having mitral or tricuspid valve surgery
    • Patients with disease of the left pleura precluding the intervention
    • Repeat sternotomies or minimally invasive procedures
  • 3601 patients were screened and 420 included
  • 212 were assigned to the left posterior pericardiotomy group and 208 to the no intervention group
  • Median age was 61 years
  • 76% were male
  • There was good baseline balance between groups

Intervention

  • A 4-5 cm vertical incision posterior to the phrenic nerve and extending from the left inferior pulmonary vein to the diaphragm
  • 212 patients
  • 3 patients in this group did not receive the intervention

Control

  • No intervention
  • 208 patients

Management common to both groups

  • Continuous cardiac rhythm monitoring for the entire postoperative in-hospital stay.
  • Daily ECG
  • In person or telephone interview at day 30 post discharge

Outcome

  • Primary outcome: the occurrence of in-hospital postoperative atrial fibrillation during the entire in-hospital stay (defined as AF for more than 30 seconds on monitor)
    • Intervention vs Control:Intention to treat analysis, post-operative atrial fibrillation significantly less in the intervention group 17% vs 32% (OR 0.44, 95% CI 0.27-0.70, p=0.0005)
  • Secondary outcomes: Intervention vs Control
    • Time spent in atrial fibrillation 1262 hours vs 2277 hours
    • Need for anti-arrhythmic medications 17% vs 31%
    • Need for anticoagulation 6% vs 14%
    • Duration of post-operative in-hospital stay 5 vs 5 days
    • When limiting the analysis to patients who had received perioperative beta-blockers (92% of total) there was still a difference between groups, with 11% vs 26% having atrial fibrillation.
  • Safety Outcomes: Intervention vs Control
    • Post-operative mortality 2 vs 1 patients
    • Pericardial effusion (as assessed on echocardiography) significantly less in intervention group: 12% vs 21% (RR 0.58, 95% CI 0.37-0.91)
    • Postoperative major events, eg stroke, myocardial infarct 3% vs 2%
    • Left pleural effusion 30% vs 32%
    • Surgery time: 306 vs 289 minutes

 

Authors’ Conclusions

  • Performing left posterior pericardiotomy at the time of cardiac surgery significantly reduces the incidence of post-operative atrial fibrillation
  • The intervention appears safe without adverse effects

Strengths

  • An important question with a clinically meaningful outcome
  • Allocation concealment, intention to treat analysis, complete follow-up
  • Exclusion of patients having mitral and tricuspid valve surgery as the pathogenesis of AF in these patients is less likely due to pericardial effusion and inflammation.
  • The intervention is low cost and adds very little extra time to surgery

Weaknesses

  • Single centre study: tend to provide larger treatment effects than multicentre trials
  • There is no information as to whether this intervention is superior to other preventative methods for AF, eg colchicine.
  • A small study likely underpowered to detect differences in hospital length of stay, mortality and other rare events
  • A large bias towards white males (>70%)
  • Nearly 80% of the operations were performed by a single surgeon, significantly limiting external validity

The Bottom Line

  • This simple intervention seems to be a safe surgical technique to reduce post-cardiac surgery atrial fibrillation
  • Multicentre trials would evaluate the external validity of this result

External Links

Metadata

Summary author: Celia Bradford
Summary date: December 17 2021
Peer-review editor: Segun Olusanya

 

 

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