Posterior Left pericardiotomy for the prevention of postoperative Atrial fibrillation after Cardiac Surgery (PALACS): study protocol for a randomized controlled trial

Partial Cardiac Denervation to Prevent Postoperative Atrial Fibrillation After Coronary Artery Bypass Grafting: The pCAD-POAF Randomized Clinical Trial

Importance

Efficient approaches to prevent postoperative atrial fibrillation (POAF) after coronary artery bypass grafting (CABG) are still needed.

Objective

To investigate whether partial cardiac denervation, achieved by cutting off the ligament of Marshall (LOM) and resecting the fat pad along the Waterston groove, can reduce the risk of POAF following CABG.

Design, Setting and Participants

This single-center, randomized clinical trial enrolled adult patients scheduled for isolated CABG in China. Enrollment was from August 15, 2022, to December 13, 2023; follow-up visits were 30 days after discharge.

Interventions

Participants were randomized into the intervention group (CABG plus partial cardiac denervation) and the control group (CABG only) in a 1:1 pattern. All participants were continuously monitored for the incidence of POAF until day 6 after the operation.

Main outcome and Measures

The primary end point was the incidence of POAF in 6 days, defined as a supraventricular arrhythmia lasting for more than 30 seconds.

Results

The trial enrolled 430 patients (79 [18.4%] female; mean [SD] age, 61.9 [7.8] years). Compared with the control group, the 6-day incidence of POAF was significantly lower in the intervention group (18.1% vs 31.6%; P = .001; risk ratio, 0.57 [95% CI, 0.41-0.81]). To further support these results, a sensitivity analysis performed with Kaplan-Meier survival curves also showed a significant reduction in the occurrence of POAF in the intervention group (hazard ratio, 0.53 [95% CI, 0.36-0.79]; P = .002). Safety assessments showed no difference between the 2 groups, while postoperative medical cost was reduced in the intervention group.

Conclusions and Relevance

This randomized clinical trial found that partial cardiac denervation was an effective procedure to reduce the occurrence of POAF after isolated CABG without additional postoperative complications. These results suggest that partial cardiac denervation may be a good option for cardiac surgeons to consider for preventing POAF after CABG.

Trial Registration

ClinicalTrials.gov Identifier: NCT05009914.

Acute pericardial postischemic inflammatory responses: Characterization using a preclinical porcine model

BACKGROUND

Pericardial fluid (PF) contains cells, proteins, and inflammatory mediators, such as cytokines, chemokines, growth factors, and matrix metalloproteinases. To date, we lack an adequate understanding of the inflammatory response that acute injury elicits in the pericardial space.

OBJECTIVE

To characterize the inflammatory profile in the pericardial space acutely after ischemia/reperfusion.

METHODS

Pigs were used to establish a percutaneous ischemia/reperfusion injury model. PF was removed from pigs at different time points postanesthesia or postischemia/reperfusion. Flow cytometry was used to characterize the immune cell composition of PF, while multiplex analysis was performed on the acellular portion of PF to determine the concentration of inflammatory mediators. There was a minimum of 3 pigs per group.

RESULTS

While native PF mainly comprises macrophages, we show that neutrophils are the predominant inflammatory cell type in the pericardial space after injury. The combination of acute ischemia/reperfusion (IR) and repeatedly accessing the pericardial space significantly increases the concentration of interleukin-1 beta (IL-1β) and interleukin-1 receptor antagonist (IL-1ra). IR significantly increases the pericardial concentration of TGFβ1 but not TGFβ2. We observed that repeated manipulation of the pericardial space can also drive a robust pro-inflammatory response, resulting in a significant increase in immune cells and the accumulation of potent inflammatory mediators in the pericardial space.

CONCLUSION

In the present study, we show that both IR and surgical manipulation can drive robust inflammatory processes in the pericardial space, consisting of an increase in inflammatory cytokines and alteration in the number and composition of immune cells.

Partial CArdiac Denervation to Prevent Postoperative Atrial Fibrillation After Coronary Artery Bypass Grafting (pCAD-POAF): Study Protocol for a Randomized Controlled Trial

Postoperative atrial fibrillation (POAF) is commonly seen in patients who underwent coronary artery bypass grafting (CABG), increasing the risk of morbidity, mortality, and hospital expenses. This study aimed to evaluate the effect of partial cardiac denervation, which is achieved by cutting off the ligament of Marshall and resecting the fat pad along the Waterston groove, on the prevention of POAF after CABG. Patients planned for CABG at our center were screened for eligibility in this study. A total of 430 patients were randomized into the intervention (partial cardiac denervation) group and control group. Intraoperative high-frequency electrical stimulation and further histologic analysis were performed in a certain number of patients to confirm the existence of ganglia. All patients were continuously monitored for the incidence of POAF through an electrophysiologic device until the sixth day postoperatively, and required to complete a 30-day follow-up (12-lead electrocardiogram and echocardiogram assessment) after discharge. The primary end point is the incidence of POAF, whereas the secondary end points are the cost-effectiveness and safety outcomes. In conclusion, this trial will evaluate whether partial cardiac denervation through cutting off the ligament of Marshall and resecting the fat pad along the Waterston groove can reduce the incidence of POAF after CABG. If this procedure is revealed to be effective and safe, it may provide a potential therapeutic approach to prevent POAF in this group of patients.

Baseline Intraoperative Left Ventricular Diastolic Function Is Associated with Postoperative Atrial Fibrillation after Cardiac Surgery

BACKGROUND

Detailed understanding of the association between intraoperative left atrial and left ventricular diastolic function and postoperative atrial fibrillation is lacking. In this post hoc analysis of the Posterior Left Pericardiotomy for the Prevention of Atrial Fibrillation after Cardiac Surgery (PALACS) trial, we aimed to evaluate the association of intraoperative left atrial and left ventricular diastolic function as assessed by transesophageal echocardiography (TEE) with postoperative atrial fibrillation.

METHODS

PALACS patients with available intraoperative TEE data (n = 402 of 420; 95.7%) were included in this cohort study. We tested the hypotheses that preoperative left atrial size and function, left ventricular diastolic function, and their intraoperative changes were associated with postoperative atrial fibrillation. Normal left ventricular diastolic function was graded as 0 and with lateral e' velocity 10 cm/s or greater. Diastolic dysfunction was defined as lateral e' less than 10 cm/s using E/e' cutoffs of grade 1, E/e' 8 or less; grade, 2 E/e' 9 to 12; and grade 3, E/e' 13 or greater, along with two criteria based on mitral inflow and pulmonary wave flow velocities.

RESULTS

A total of 230 of 402 patients (57.2%) had intraoperative diastolic dysfunction. Posterior pericardiotomy intervention was not significantly different between the two groups. A total of 99 of 402 patients (24.6%) developed postoperative atrial fibrillation. Patients who developed postoperative atrial fibrillation more frequently had abnormal left ventricular diastolic function compared to patients who did not develop postoperative atrial fibrillation (75.0% [n = 161 of 303] vs. 57.5% [n = 69 of 99]; P = 0.004). Of the left atrial size and function parameters, only delta left atrial area, defined as presternotomy minus post-chest closure measurement, was significantly different in the no postoperative atrial fibrillation versus postoperative atrial fibrillation groups on univariate analysis (-2.1 cm2 [interquartile range, -5.1 to 1.0] vs. 0.1 [interquartile range, -4.0 to 4.8]; P = 0.028). At multivariable analysis, baseline abnormal left ventricular diastolic function (odds ratio, 2.02; 95% CI, 1.15 to 3.63; P = 0.016) and pericardiotomy intervention (odds ratio, 0.46; 95% CI, 0.27 to 0.78, P = 0.004) were the only covariates independently associated with postoperative atrial fibrillation.

CONCLUSIONS

Baseline preoperative left ventricular diastolic dysfunction on TEE, not left atrial size or function, is independently associated with postoperative atrial fibrillation. Further studies are needed to test if interventions aimed at optimizing intraoperative left ventricular diastolic function during cardiac surgery may reduce the risk of postoperative atrial fibrillation.

EDITOR’S PERSPECTIVE

Characteristics of Postoperative Atrial Fibrillation and the Effect of Posterior Pericardiotomy

BACKGROUND

Postoperative atrial fibrillation (POAF) is a frequent complication of cardiac surgery. However, only a few detailed descriptions of the arrhythmia have been reported. We aim to describe the characteristics, outcomes, and variables associated with POAF and to evaluate how posterior pericardiotomy (PP) affects POAF characteristics.

METHODS

In this post hoc analysis of the Posterior left pericardiotomy for the prevention of AtriaL fibrillation After Cardiac Surgery (PALACS) trial, we describe POAF characteristics based on continuous in-hospital telemetry data.

RESULTS

Of 420 patients, 103 (24.5%) developed POAF. Median time to onset was 50.3 hours; 70.9% of events occurred within 3 days. Hemodynamic instability and rapid ventricular response occurred in 8.7% and 51.5% of cases, respectively. Most POAF patients received antiarrhythmics (97.1%), 22.3% electrical cardioversion, and 40.8% systemic anticoagulation. Median POAF duration was 24.0 hours; 70.9% of cases resolved within 36 hours. Median POAF burden was 15.9%. All patients were in sinus rhythm at follow-up. POAF was associated with longer hospitalization (7 vs 6 days; P < .001), but not increased mortality or morbidity. PP reduced POAF incidence (17.7% vs 31.3%; P = .001), especially after postoperative day 2 (time to POAF onset 41.9 vs 57.1 hours; P = .01). Age was associated with POAF. Female sex, coronary artery bypass grafting, beta blockers, and PP were inversely associated.

CONCLUSIONS

POAF remains frequent after cardiac surgery. Hemodynamic instability is rare, although rapid ventricular response and need for electrical cardioversion are frequent. POAF burden is significant, and the arrhythmias resolve within 30 days. PP reduces POAF especially after postoperative day 2.

Pericardial Inflammatory Mediators That Can Drive Postoperative Atrial Fibrillation in Cardiac Surgery Patients

Postoperative atrial fibrillation (POAF) is a common dysrhythmia that affects a significant number of patients undergoing cardiac surgery. Many studies aim to better understand this complex postsurgical complication by analysing circulating biomarkers in patients who develop POAF. More recently, the pericardial space was shown to contain inflammatory mediators that could trigger POAF. In this review we summarise recent studies that examine the immune mediators present in the pericardial space and their potential implications for the pathophysiology of POAF in cardiac surgery patients. Ongoing research in this area should better delineate the multifactorial etiology of POAF, where specific markers may be targeted to reduce the incidence of POAF and improve outcomes for this patient population.

Postoperative pericardial effusion, pericardiotomy, and atrial fibrillation: An explanatory analysis of the PALACS trial

BACKGROUND

In the Posterior left pericardiotomy for the prevention of atrial fibrillation after cardiac surgery (PALACS) trial, posterior pericardiotomy was associated with a significant reduction in postoperative atrial fibrillation (POAF) after cardiac surgery. We aimed to investigate the mechanisms underlying this effect.

METHODS

We included PALACS patients with available echocardiographic data (n = 387/420, 92%). We tested the hypotheses that the reduction in POAF with the intervention was associated with 1) a reduction in postoperative pericardial effusion and/or 2) an effect on left atrial size and function. Spline and multivariable logistic regression analyses were used.

RESULTS

Most patients (n = 307, 79%) had postoperative pericardial effusions (anterior 68%, postero-lateral 51.9%). The incidence of postero-lateral effusion was significantly lower in patients undergoing pericardiotomy (37% vs 67%; P < .001). The median size of anterior effusion was comparable between patients with and without POAF (5.0 [IQR 3.0-7.0] vs 5.0 [IQR 3.0-7.5] mm; P = .42), but there was a nonsignificant trend towards larger postero-lateral effusion in the POAF group (5.0 [IQR 3.0-9.0] vs 4.0 [IQR 3.0-6.4] mm; P = .06). There was a non-linear association between postero-lateral effusion and POAF at a cut-off at 10 mm (OR 2.70; 95% CI 1.13, 6.47; P = .03) that was confirmed in multivariable analysis (OR 3.5, 95% CI 1.17, 10.58; P = 0.02). Left atrial dimension and function did not change significantly after posterior pericardiotomy.

CONCLUSIONS

Reduction in postero-lateral pericardial effusion is a plausible mechanism for the effect of posterior pericardiotomy in reducing POAF. Measures to reduce postoperative pericardial effusion are a promising approach to prevent POAF.

Chest Tube Management: Past, Present, and Future Directions for Developing Evidence-Based Best Practices

In the field of modern cardiothoracic surgery, chest drainage has become ubiquitous and yet characterized by a wide variation in practice. Meanwhile, the evolution of chest drain technology has created gaps in knowledge that represent opportunities for new research to support the development of best practices in chest drain management. The chest drain is an indispensable tool in the recovery of the cardiac surgery patient. However, decisions about chest drain management-including those about type, material, number, maintenance of patency, and the timing of removal-are largely driven by tradition due to a scarcity of quality evidence. This narrative review surveys the available evidence regarding chest-drain management practices with the objective of highlighting scientific gaps, unmet needs, and opportunities for further research.

Left Atrial Strain Quantification by Intraoperative Transesophageal Echocardiography: Validation With Transthoracic Echocardiography

OBJECTIVE

Whereas left atrial (LA) strain has been well-validated using transthoracic echocardiography (TTE), its detection using transesophageal echocardiography (TEE) has not been studied. Conventional transesophageal views are known to be limited due to the posterior location of the LA. Here, the feasibility and accuracy of the deep transgastric long-axis LA focused view for peak atrial longitudinal strain (PALS) quantification was tested.

DESIGN

This was a retrospective study of patients who underwent elective cardiac surgery between 2018 and 2020. TEE deep transgastric long-axis view was compared to TTE 4-chamber atrial focused view as the reference standard. LA area, volume, and PALS were quantified independently.

SETTING

At Weill Cornell Medicine, a single, large academic medical center.

PARTICIPANTS

The population comprised 42 patients undergoing cardiac surgery who had a TTE and TEE within 14.9 ± 20.8 days.

INTERVENTIONS

TTE, TEE, and cardiac surgery.

MEASUREMENTS AND MAIN RESULTS

TEE-derived PALS strongly correlated with TTE- derived PALS (r = 0.92, p < 0.001), though absolute PALS were lower (20.7 ± 6.0% v 25.7 ± 6.8%; p < 0.001). Mean TEE-derived atrial length was similar to TTE-derived length (5.18 ± 0.61 cm v 5.24 ± 0.61 cm; p = 0.38), but mean LA area was significantly smaller (16.7 ± 3.5 cm2v 18.9 ± 3.7 cm2; p < 0.001), with significant correlations between the 2 modalities for both (r = 0.74, 0.74, respectively; all p < 0.001).

CONCLUSION

This exploratory study supported the feasibility of TEE for assessing LA longitudinal strain. There was an excellent correlation between atrial strain derived via TEE versus TTE, although values tended to be smaller on TEE, and bias between values was highly variable, suggesting that the values were not interchangeable.

Posterior left pericardiotomy for the prevention of atrial fibrillation after cardiac surgery: an adaptive, single-centre, single-blind, randomised, controlled trial

BACKGROUND

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. Pericardial effusion is common after cardiac surgery and can trigger atrial fibrillation. We tested the hypothesis that posterior left pericardiotomy, a surgical manoeuvre that drains the pericardial space into the left pleural cavity, might reduce the incidence of atrial fibrillation after cardiac surgery.

METHODS

In this adaptive, randomised, controlled trial, we recruited adult patients (aged ≥18 years) undergoing elective interventions on the coronary arteries, aortic valve, or ascending aorta, or a combination of these, performed by members of the Department of Cardiothoracic Surgery from Weill Cornell Medicine at the New York Presbyterian Hospital in New York, NY, USA. Patients were eligible if they had no history of atrial fibrillation or other arrhythmias or contraindications to the experimental intervention. Eligible patients were randomly assigned (1:1), stratified by CHA₂DS₂-VASc score and using a mixed-block randomisation approach (block sizes of 4, 6, and 8), to posterior left pericardiotomy or no intervention. Patients and assessors were blinded to treatment assignment. Patients were followed up until 30 days after hospital discharge. The primary outcome was the incidence of atrial fibrillation during postoperative in-hospital stay, which was assessed in the intention-to-treat (ITT) population. Safety was assessed in the as-treated population. This study is registered with ClinicalTrials.gov, NCT02875405, and is now complete.

FINDINGS

Between Sept 18, 2017, and Aug 2, 2021, 3601 patients were screened and 420 were included and randomly assigned to the posterior left pericardiotomy group (n=212) or the no intervention group (n=208; ITT population). The median age was 61·0 years (IQR 53·0-70·0), 102 (24%) patients were female, and 318 (76%) were male, with a median CHA₂DS₂-VASc score of 2·0 (IQR 1·0-3·0). The two groups were balanced with respect to clinical and surgical characteristics. No patients were lost to follow-up and data completeness was 100%. Three patients in the posterior left pericardiotomy group did not receive the intervention. In the ITT population, the incidence of postoperative atrial fibrillation was significantly lower in the posterior left pericardiotomy group than in the no intervention group (37 [17%] of 212 vs 66 [32%] of 208 [p=0·0007]; odds ratio adjusted for the stratification variable 0·44 [95% CI 0·27-0·70; p=0·0005]). Two (1%) of 209 patients in the posterior left pericardiotomy group and one (<1%) of 211 in the no intervention group died within 30 days after hospital discharge. The incidence of postoperative pericardial effusion was lower in the posterior left pericardiotomy group than in the no intervention group (26 [12%] of 209 vs 45 [21%] of 211; relative risk 0·58 [95% CI 0·37-0·91]). Postoperative major adverse events occurred in six (3%) patients in the posterior left pericardiotomy group and in four (2%) in the no intervention group. No posterior left pericardiotomy related complications were seen.

INTERPRETATION

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.

FUNDING

None.

The 2020 Canadian Cardiovascular Society/Canadian Heart Rhythm Society Comprehensive Guidelines for the Management of Atrial Fibrillation

The Canadian Cardiovascular Society (CCS) atrial fibrillation (AF) guidelines program was developed to aid clinicians in the management of these complex patients, as well as to provide direction to policy makers and health care systems regarding related issues. The most recent comprehensive CCS AF guidelines update was published in 2010. Since then, periodic updates were published dealing with rapidly changing areas. However, since 2010 a large number of developments had accumulated in a wide range of areas, motivating the committee to complete a thorough guideline review. The 2020 iteration of the CCS AF guidelines represents a comprehensive renewal that integrates, updates, and replaces the past decade of guidelines, recommendations, and practical tips. It is intended to be used by practicing clinicians across all disciplines who care for patients with AF. The Grading of Recommendations, Assessment, Development and Evaluations (GRADE) system was used to evaluate recommendation strength and the quality of evidence. Areas of focus include: AF classification and definitions, epidemiology, pathophysiology, clinical evaluation, screening and opportunistic AF detection, detection and management of modifiable risk factors, integrated approach to AF management, stroke prevention, arrhythmia management, sex differences, and AF in special populations. Extensive use is made of tables and figures to synthesize important material and present key concepts. This document should be an important aid for knowledge translation and a tool to help improve clinical management of this important and challenging arrhythmia.

Differential myocardial strain in the early postoperative period in patients receiving arterial vs venous bypass grafts: A hypothesis-generating study

OBJECTIVE

Revascularization via coronary artery bypass grafting (CABG) remains a common therapy for coronary artery disease. CABG-based revascularization is most commonly performed via either single arterial graft (SAG) or multiple arterial grafting (MAG) strategies. Echo-derived global and regional longitudinal strain was used to test where SAG or MAG results in immediate differences in left ventricular (LV) function after CABG.

MATERIALS AND METHODS

Pre- and postprocedural intraoperative transesophageal echos were prospectively collected. Two-dimensional LV images were analyzed for global and regional longitudinal strain (GLS), LV ejection fraction, end-diastolic volume, end-systolic volume, and stroke volume (SV).

RESULTS

Twenty patients underwent open, on-pump CABG (63.9 ± 10 years old, 85% male; 10 with SAG and 10 with MAG. Preprocedural GLS significantly differed between patients with SAG and MAG, with patients with MAG having greater GLS (mean [standard deviation, SD], 20.41 [5.54]) than patients with SAG (16.28 [3.48]). After CABG, in patients with MAG, LV strain decreased both globally (-1.13 [3.15]) and regionally in the anterior-lateral (-1.22 [3.84]) and inferior-lateral regions (-1.32 [5.69]), along with LVEF. In patients with SAG, LV strain increased after CABG globally (1.34 [2.73]) and regionally in the anterior-lateral (1.20 [6.49]) and inferior-lateral regions (0.39 [7.26]), as did LVEF and SV. Postprocedure, more patients with MAG were given vasopressor (100% vs 60%) and inotrope infusions (70% vs 40%) than patients with SAG.

CONCLUSIONS

After CABG, LV function quantified through GLS changes both globally and regionally increased after SAG and decreased after MAG. This finding may have important clinical implications in terms of optimizing intraoperative management for patients with CABG and have the potential to guide the improvement of clinical outcomes.

Echocardiographic predictors of intraoperative right ventricular dysfunction: a 2D and speckle tracking echocardiography study

Background

Intraoperative or post procedure right ventricular (RV) dysfunction confers a poor prognosis in the post-operative period. Conventional predictors for RV function are limited due the effect of cardiac surgery on traditional RV indices; novel echocardiographic techniques hold the promise to improve RV functional stratification.

Methods

Comprehensive echocardiographic data were collected prospectively during elective cardiac surgery. Tricuspid annular plane systolic excursion (TAPSE), peak RV systolic velocity (S′), and RV fractional area change (FAC) were quantified on transesophageal echo (TEE). RV global and regional (septal and free wall) longitudinal strain was quantified using speckle-tracking echo in RV-focused views. Two intraoperative time points were used for comparison: pre-sternotomy (baseline) and after chest closure.

Results

The population was comprised of 53 patients undergoing cardiac surgery [15.1% coronary artery bypass graft (CABG) only, 28.3% valve only, 50.9% combination (e.g. valve/CABG, valve/aortic graft) surgeries], among whom 38% had impaired RV function at baseline defined as RV FAC < 35%. All conventional RV functional indices including TAPSE, S′ and FAC declined immediately following CPB (1.5 ± 0.3 vs.1.1 ± 0.3 cm, 8.0 ± 2.1 vs. 6.2 ± 2.5 cm/s, 36.8 ± 9.3 vs. 29.3 ± 10.6%; p < 0.001 for all). However, left ventricular (LV) and RV hemodynamic parameters remained unchanged (LV ejection fraction (EF): 56.8 ± 13.0 vs. 55.8 ± 12.9%; p = 0.40, pulmonary artery systolic pressure (PASP): 26.5 ± 7.4 vs 27.3 ± 6.7 mmHg; p = 0.13). Speckle tracking echocardiographic data demonstrated a significant decline in RV global longitudinal strain (GLS) [19.0 ± 6.5 vs. 13.5 ± 6.9%, p < 0.001]. Pre-procedure FAC, GLS and free wall strain predicted RV dysfunction at chest closure (34.7 ± 9.1 vs. 41.6 ± 8.1%, p = 0.01, 17.7 ± 6.5 vs. 21.8 ± 5.4%; p = 0.03, 20.3 ± 6.4 vs. 24.2 ± 5.8%; p = 0.04), whereas traditional linear RV indices such as TAPSE and RV S′ at baseline had no impact on intraoperative RV dysfunction (p = NS for both).

Conclusions

Global and regional RV function, as measured by 2D indices and strain, acutely decline intraoperatively. Impaired RV strain is associated with intraoperative RV functional decline and provides incremental value to traditional RV indices in predicting those who will develop RV dysfunction.