Background
Postoperative atrial fibrillation (POAF) is a common complication following cardiac surgery with an incidence of 30–40% [
1,
2]. POAF has been associated with stroke, systemic embolism, and cardiac failure. Its detection mandates additional treatment with varying combinations of drugs to control cardiac rate and/or rhythm, anticoagulation, and/or electrical cardioversion; each of which have side effects that cannot be ignored. As a result, POAF prolongs hospital stay and increases hospital expenditure [
1]. Several strategies aimed at reducing the incidence of POAF have been investigated, including treatment with beta-blockers, amiodarone, and statins, all with unsatisfactory results [
1,
3‐
5]. In a few studies, performing a posterior left pericardiotomy has been associated with a reduction in the incidence of POAF by allowing drainage of blood and fluid from the posterior pericardial space [
6‐
8]. Performing a posterior left pericardiotomy is theorized to prevent POAF by allowing the posterior pericardial space to drain into the left side of the chest and be evacuated by a chest tube. This prevents blood and fluid from accumulating behind the left atrium, causing atrial irritation which can lead to POAF. However, previous studies are associated with some limitations such as: sample size, inclusion/exclusion criteria, randomization procedure, and suboptimal electrocardiographic monitoring strategies. Moreover, posterior left pericardiotomy requires additional operative time and can be associated with procedure-specific complications such as an increased incidence of left-sided pleural effusion. As a result, current evidence on posterior pericardiotomy has failed to translate into changes to clinical practice.
The primary objective of the present prospective, randomized, controlled study is to assess whether performing a posterior left pericardiotomy during open cardiac surgery procedures (coronary artery bypass grafting (CABG), aortic valve replacement, interventions to the ascending aorta or their combination) results in a reduction in the incidence of POAF.
The secondary objectives of this study are to assess:
-
The time spent in atrial fibrillation
-
The duration of the hospitalization
-
Safety measures such as: pericardial and left-sided pleural effusion as a complication of this procedure, death, and major adverse events (MAE)
This study contributes to the cardiovascular community’s understanding of POAF and has the potential to offer an alternative treatment option that mitigates the need for anticoagulation and antiarrhythmic drugs along with their associated side effects. This is especially important for patients who have contraindications to either anticoagulation or antiarrhythmic therapy.
Discussion
POAF has continued to be a source of major morbidity, prolongation of hospitalization and additional costs following cardiac surgery. In the surgical literature, an average of one additional hospital day with a burden of about €1800 per patient has been reported. Early treatment was associated with a lower incidence of cerebrovascular events [
16]. In another risk-adjusted study, POAF resulted in a twofold increase in mortality (adjusted odds ratio = 2.04,
p < 0.001), two additional intensive care unit (ICU) days (
p < 0.001), three additional hospital days (
p < 0.001), and $3000 (
p < 0.001) and $9000 (
p < 0.001) of increased ICU and total hospital-related costs, respectively [
17]. Although numerous methods and treatment options have been examined over the years, none has proven to be optimal. Currently, pharmacological agents are the most often used modality for the prevention and treatment of POAF. While some of these agents may help reduce POAF, their side effects and costs cannot be ignored. Thus, a cost-effective and a low-risk intervention for POAF is yet to be provided. This topic is of great interest to the cardiovascular community and the results of this study could have profound implications on current practices. The potential to decrease POAF and its associated complications will improve our clinical knowledge and surgical practice while decreasing patient morbidity and mortality. Similar to any surgical procedure, posterior pericardiotomy is associated with potential complications. Aside from the complications associated with any cardiac procedure, it is associated with a risk of phrenic nerve injury, cardiac herniation, and extended drainage time of left-sided pleural effusions. These complications can be prevented by careful technique and postoperative management. Proper operative identification of the phrenic nerve should be emphasized. In addition, special attention should be given to not extend the posterior pericardiotomy incision beyond 4 cm to avoid the risk of cardiac herniation [
6].
In a previous meta-analysis by Kaleda et al., posterior pericardiotomy was found to significantly reduce the incidence of POAF. This study showed a substantial reduction in total arrhythmias and atrial fibrillation in the posterior pericardiotomy group (odds ratio 0.31 and 0.33, respectively). The reported number needed to treat was six patients to prevent one case of atrial fibrillation. However, this meta-analysis was non-conclusive as it was based on seven studies which were either cohort or non-blinded studies. In addition, the outcomes assessed were not homogenous, with primary outcome measures varying between the incidence of postoperative pericardial effusions, arrhythmias or atrial fibrillation [
6]. In 1999, Kurlay et al. reported the results of a randomized controlled trial. In 200 patients, atrial fibrillation rate (6%) was significantly lower in the posterior pericardiotomy group in comparison with the control group (34%) (
p < 0.001). In the control group, early and late pericardial effusion rates were 54% and 21%, respectively, in contrast to that of the posterior pericardiotomy group which was zero for both (
p < 0.001). Delayed pericardial tamponade was also significantly lower in group I (0% vs. 10%;
p = 0.001). However, in this trial, patients receiving beta-blockers were excluded and, therefore, its results are not relevant to current practice [
7]. In a more recent randomized trial, similar methodology was utilized with promising results in 50 posterior pericardiotomy patients. POAF was significantly lower in the posterior pericardiotomy group compared with the control group (10% vs. 30%,
p < 0.010). Perioperative pericardial effusion rate was 12% compared to 42% in the control group (
p < 0.001). The overall incidence of total arrhythmias in patients with early pericardial effusion was significantly higher than in those without this complication (18 vs. 9 patients) [
8].
The present randomized study should significantly contribute to the assessment of the role of posterior pericardiotomy to reduce the incidence of atrial fibrillation after cardiac surgery.
Trial status
This trial was registered at ClinicalTrials.gov in July 2016 with protocol record 1502015867 and identifier NCT02875405.
The date of initial recruitment: 1 August 2017.
The approximate date when recruitment will be completed: 1 August 2018.
MG: Stephen and Suzanne Weiss Professor in Cardiothoracic Surgery (II), Director of Translational and Clinical Research
LBO: Research Fellow at the Department of Cardiothoracic Surgery, Weill Cornell Medicine and a general surgery resident at Rutgers University.
CL: Assistant Professor of Cardiothoracic Surgery at the Department of Cardiothoracic Surgery, Weill Cornell Medicine
TS: Professor at the Department of Cardiovascular Sciences, Catholic University, Rome, Italy
LNG: Chairman of Cardiothoracic Surgery, Weill Cornell Medicine
KOP: Associate Professor of Clinical Anesthesiology, Weill Cornell Medicine
NSI: Associate Professor of Clinical Anesthesiology, Weill Cornell Medicine
LQR: Assistant Professor of Clinical Anesthesiology, Weill Cornell Medicine
MM: Professor of Cardiothoracic Surgery, Catholic University, Rome, Italy
FC: Professor of Cardiology, Catholic University, Rome, Italy
MM: Research Biostatistician at the Department of Cardiothoracic Surgery, Weill Cornell Medicine
JRL: Research Fellow at the Department of Cardiothoracic Surgery, Weill Cornell Medicine and a general surgery resident.
AAA: Research Fellow at the Department of Cardiothoracic Surgery, Weill Cornell Medicine
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