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

• Posterior left pericardiotomy for prevention of atrial fibrillation after cardiac surgery
• Postoperative atrial fibrillation after cardiac surgery: a systematic review and meta-analysis

Metadata

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