Anticoagulation for post-operative atrial fibrillation after isolated coronary artery bypass grafting: a meta-analysis

BACKGROUND AND AIMS

This study aimed to evaluate clinical outcomes in patients developing post-operative atrial fibrillation (POAF) after coronary artery bypass grafting (CABG) and characterize variations in oral anticoagulation (OAC) use, benefits, and complications.

METHODS

A systematic search identified studies on new-onset POAF after CABG and OAC initiation. Outcomes included risks of thromboembolic events, bleeding, and mortality. Furthermore, a meta-analysis was conducted on these outcomes, stratified by the use or non-use of OAC.

RESULTS

The identified studies were all non-randomized. Among 1 698 307 CABG patients, POAF incidence ranged from 7.9% to 37.6%. Of all POAF patients, 15.5% received OAC. Within 30 days, thromboembolic events occurred at rates of 1.0% (POAF: 0.3%; non-POAF: 0.8%) with 2.0% mortality (POAF: 1.0%; non-POAF: 0.5%). Bleeding rates were 1.1% for POAF patients and 2.7% for non-POAF patients. Over a median of 4.6 years, POAF patients had 1.73 thromboembolic events, 3.39 mortality, and 2.00 bleeding events per 100 person-years; non-POAF patients had 1.14, 2.19, and 1.60, respectively. No significant differences in thromboembolic risks [effect size -0.11 (-0.36 to 0.13)] and mortality [effect size -0.07 (-0.21 to 0.07)] were observed between OAC users and non-users. However, OAC use was associated with higher bleeding risk [effect size 0.32 (0.06-0.58)].

CONCLUSIONS

In multiple timeframes following CABG, the incidence of complications in patients who develop POAF is low. The use of OAC in patients with POAF after CABG is associated with increased bleeding risk.

Differences in Postoperative Atrial Fibrillation Incidence and Outcomes After Cardiac Surgery According to Assessment Method and Definition: A Systematic Review and Meta-Analysis

BACKGROUND

Postoperative atrial fibrillation (POAF) is the most frequent complication of cardiac surgery. Despite clinical and economic implications, ample variability in POAF assessment method and definition exist across studies. We performed a study-level meta-analysis to evaluate the influence of POAF assessment method and definition on its incidence and association with clinical outcomes.

METHODS AND RESULTS

A systematic literature search was conducted to identify studies comparing the outcomes of patients with and without POAF after cardiac surgery that also reported POAF assessment method. The primary outcome was POAF incidence. The secondary outcomes were in-hospital mortality, stroke, intensive care unit length of stay, and postoperative length of stay. Fifty-nine studies totaling 197 774 patients were included. POAF cumulative incidence was 26% (range: 7.3%-53.1%). There were no differences in POAF incidence among assessment methods (27%, [range: 7.3%-53.1%] for continuous telemetry, 27% [range: 7.9%-50%] for telemetry plus daily ECG, and 19% [range: 7.8%-42.4%] for daily ECG only; P>0.05 for all comparisons). No differences in in-hospital mortality, stroke, intensive care unit length of stay, and postoperative length of stay were found between assessment methods. No differences in POAF incidence or any other outcomes were found between POAF definitions. Continuous telemetry and telemetry plus daily ECG were associated with higher POAF incidence compared with daily ECG in studies including only patients undergoing isolated coronary artery bypass grafting.

CONCLUSIONS

POAF incidence after cardiac surgery remains high, and detection rates are variable among studies. POAF incidence and its association with adverse outcomes are not influenced by the assessment method and definition used, except in patients undergoing isolated coronary artery bypass grafting.

Atrial fibrillation after cardiac surgery: A systematic review and meta-analysis

OBJECTIVE

New-onset postoperative atrial fibrillation (POAF) after cardiac surgery is common, with rates up to 60%. POAF has been associated with early and late stroke, but its association with other cardiovascular outcomes is less known. The objective was to perform a meta-analysis of the studies reporting the association of POAF with perioperative and long-term outcomes in patients with cardiac surgery.

METHODS

We performed a systematic review and a meta-analysis of studies that presented outcomes for cardiac surgery on the basis of the presence or absence of POAF. MEDLINE, EMBASE, and the Cochrane Library were assessed; 57 studies (246,340 patients) were selected. Perioperative mortality was the primary outcome. Inverse variance method and random model were performed. Leave-one-out analysis, subgroup analyses, and metaregression were conducted.

RESULTS

POAF was associated with perioperative mortality (odds ratio [OR], 1.92; 95% confidence interval [CI], 1.58-2.33), perioperative stroke (OR, 2.17; 95% CI, 1.90-2.49), perioperative myocardial infarction (OR, 1.28; 95% CI, 1.06-1.54), perioperative acute renal failure (OR, 2.74; 95% CI, 2.42-3.11), hospital (standardized mean difference, 0.80; 95% CI, 0.53-1.07) and intensive care unit stay (standardized mean difference, 0.55; 95% CI, 0.24-0.86), long-term mortality (incidence rate ratio [IRR], 1.54; 95% CI, 1.40-1.69), long-term stroke (IRR, 1.33; 95% CI, 1.21-1.46), and longstanding persistent atrial fibrillation (IRR, 4.73; 95% CI, 3.36-6.66).

CONCLUSIONS

The results suggest that POAF after cardiac surgery is associated with an increased occurrence of most short- and long-term cardiovascular adverse events. However, the causality of this association remains to be established.

Anticoagulation management of postoperative atrial fibrillation after cardiac surgery: A systematic review

BACKGROUND

Postoperative atrial fibrillation (POAF) often complicates cardiac surgery and is associated with increased mortality and risk of thromboembolism. However, the optimal oral anticoagulation (OAC) strategy is uncertain. We performed a systematic review to examine the OAC practice patterns and efficacy in these circumstances.

METHODS

MEDLINE and EMBASE were searched from 2000 to 2019 using the search terms cardiac surgical procedures, cardiac surgery, postoperative complications, atrial fibrillation, atrial flutter, and terms for anticoagulants. Collected data included anticoagulation patterns (time of initiation, type, and duration) and outcomes (stroke, bleeding, and mortality).

RESULTS

From 763 records, 4 prospective and 13 retrospective studies were included totaling 44,908 patients with 8929 (19.9%) who developed POAF. Anticoagulation rates ranged from 4% to 43% (mean 21% overall). Sixteen studies used warfarin, 3 nonvitamin K OAC (NOAC), and 2 both. Four studies reported the use of bridging unfractionated or low-molecular-weight heparin. Concomitant antiplatelet therapy was reported in half the studies, ranging from 80% to 99%. OAC use was associated with lower risk of thromboembolic events in two retrospective studies (including a national Danish cohort with 2108 patients with POAF). Patients discharged on warfarin experienced reduced mortality in a large, single center, retrospective analysis, but no association was observed in the Danish cohort.

CONCLUSION

There is wide practice variation in the uptake, timing of initiation, duration, and choice of OAC for POAF following cardiac surgery. The evidence is largely retrospective and insufficient to assess the efficacy of different OAC strategies. Further studies are warranted to guide clinical practice.

Rationale and Design of the Randomized Controlled Trial of New Oral Anticoagulants vs. Warfarin for post Cardiac Surgery Atrial Fibrillation: The NEW-AF Trial

: New onset atrial fibrillation commonly occurs following cardiac surgery and is associated with increased rates of stroke and mortality. In non-surgical patients with atrial fibrillation, novel oral anticoagulants (NOACs) have been shown to confer equivalent benefits for stroke prevention with less bleeding risk and less tedious monitoring requirements compared with Warfarin. However, NOACs have yet to be adopted widely in cardiac surgery patients. The NEW-AF study has been designed as a pragmatic, prospective, randomized controlled trial that will compare financial, convenience and safety outcomes for patients with new onset atrial fibrillation after cardiac surgery who are treated with NOACs versus Warfarin. Study results may contribute to optimizing the options for stroke prophylaxis in cardiac surgery patients and catalyze more widespread application of NOAC therapy in this patient population. The trial is registered with clinicaltrials.gov under registration number NCT03702582Rationale and Design of the Randomized Controlled Trial of New Oral Anticoagulants vs. Warfarin for post Cardiac Surgery Atrial Fibrillation: The NEW-AF Trial.

New-onset atrial fibrillation and outcomes following isolated coronary artery bypass surgery: A systematic review and meta-analysis

Prior meta‐analyses have shown that new‐onset atrial fibrillation (NOAF) occurs in up to 40% of patients following cardiac surgery and is associated with substantial major adverse cardiovascular events. The stroke and mortality implications of NOAF in isolated CABG without concomitant valve surgery is not known. We thought that NOAF would be associated with increased risk of stroke and mortality, even in patients undergoing isolated CABG. A blinded review of studies from MEDLINE, CENTRAL, and Web of Science was done by two independent investigators. Stroke, 30‐day/hospital mortality, long‐term cardiovascular mortality, and long‐term (>1 year) all‐cause mortality were analyzed. We used Review Manager Version 5.3 to perform pooled analysis of outcomes. Of 4461 studies identified, 19 studies (n = 129 628) met inclusion criteria. NOAF incidence ranged from 15% to 36%. NOAF was associated with increased risk of stroke (unadjusted OR 2.15 [1.82, 2.53] [P < .00001]; adjusted OR 1.88 [1.02, 3.46] [P = .04]). NOAF was associated with increased 30‐day/hospital mortality (OR 2.35 [1.67, 3.32] [P < .00001]) and long‐term cardiovascular mortality (OR 2.04 [1.35, 3.09] [P = .0007]) NOAF was associated with increased long‐term all‐cause mortality (unadjusted OR 1.79 [1.63, 1.96] [P < .00001]; adjusted OR 1.58 [1.24, 2.00] [P = .0002]). We found that the incidence of NOAF following isolated CABG is high and is associated with increased stroke rate and mortality. Early recognition and management of NOAF could improve outcomes.

New-onset postoperative atrial fibrillation impact on 5-year clinical outcomes and costs

OBJECTIVE

The impact of new-onset postoperative atrial fibrillation (POAF) following coronary artery bypass grafting (CABG) surgery on long-term clinical outcomes and costs is not known. This subanalysis of the Veterans Affairs "Randomized On/Off Bypass Follow-up Study" compared 5-year outcomes and costs between patients with and without POAF.

METHODS

Of the 2203 veterans in the study, 100 with pre-CABG atrial fibrillation (93) or missing data (7) were excluded (4.8%). Unadjusted and risk-adjusted outcomes were compared between new-onset POAF (n = 551) and patients without POAF (n = 1552). Five-year clinical outcomes included mortality, major adverse cardiovascular events (MACE, comprising mortality, repeat revascularization, and myocardial infarction), MACE subcomponents, stroke, and costs. A stringent P value of ≤.01 was required to identify statistical significance.

RESULTS

Patients with POAF were older and had more complex comorbidities. Unadjusted 5-year all-cause mortality was 16.3% POAF versus 11.9% no-POAF, P = .008. Unadjusted cardiac-mortality was 7.4% versus 4.8%, P = .022. There were no differences between groups in any other unadjusted outcomes including MACE or stroke. After risk adjustment, there were no significant differences between groups in 5-year all-cause mortality (POAF odds ratio, 1.19; 99% confidence interval, 0.81-1.75) or cardiac mortality (odds ratio, 1.51, 99% confidence interval, 0.88-2.60). Adjusted first-year post-CABG costs were $15,300 greater for patients with POAF, but 2- through 5-year costs were similar.

CONCLUSIONS

No 5-year risk-adjusted outcome differences were found between patients with and without POAF after CABG. Although first-year costs were greater in patients with POAF, this difference did not persist in subsequent years.

Are Serum Potassium and Magnesium Levels Associated with Atrial Fibrillation After Cardiac Surgery?

OBJECTIVES

Potassium and magnesium are frequently administered after cardiac surgery to reduce the risk of atrial fibrillation (AF). The evidence for this practice is unclear. This study was designed to evaluate the relationship between serum potassium and magnesium levels and AF after cardiac surgery.

DESIGN

Observational cohort study.

SETTING

A cardiac intensive care unit in the United Kingdom.

PARTICIPANTS

Patients undergoing cardiac surgery between January 2013 and November 2017.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Cardiac rhythm was assessed using continuous electrocardiogram (ECG) monitoring in 3,068 patients on the cardiac intensive care unit. Associations between serum potassium and magnesium concentrations extracted from hospital databases and postoperative AF were assessed using univariable and multivariable analyses. The association between electrolyte supplementation therapy and AF was also analyzed. AF developed within 72 hours of cardiac surgery in 545 (17.8%) of the 3,068 patients. After adjusting for logistic EuroSCORE, surgery type, cardiopulmonary bypass time and age, mean serum potassium concentration <4.5 mmol/L was associated with an increased risk of AF (odds ratio [OR] 1.43 (95% confidence interval (CI): 1.17-1.75), p < 0.001). Mean magnesium concentration <1.0 mmol/L was not associated with an increased risk of AF (OR 0.89, 0.71-1.13, p = 0.342), but the administration of magnesium was associated with increased risk of developing AF (OR 1.61, 1.33-1.96, p < 0.001).

CONCLUSIONS

Maintaining a serum potassium concentration ≥4.5 mmol/L after cardiac surgery may reduce the incidence of postoperative AF. Magnesium supplementation was associated with an increased risk of postoperative AF. Prospective randomized trials are required to clarify these associations.

New-Onset Atrial Fibrillation After Coronary Artery Bypass Graft and Long-Term Risk of Stroke: A Meta-Analysis

BACKGROUND

New-onset atrial fibrillation (NOAF) after coronary artery bypass graft is related to an increased short-term risk of stroke and mortality. We investigated whether the long-term risk of stroke is increased.

METHODS AND RESULTS

We performed a systematic review and meta-analysis of studies that included patients who had coronary artery bypass graft and who afterwards developed NOAF during their index admission; these patients did not have previous atrial fibrillation. The primary outcome was risk of stroke at 6 months or more in patients who developed NOAF compared with those who did not. Odds ratios, relative risk, and hazard ratios were considered equivalent; outcomes were pooled on the log-ratio scale using a random-effects model and reported as exponentiated effect-sizes. We included 16 studies, comprising 108 711 participants with a median follow-up period of 2.05 years. Average participant age was 66.8 years, with studies including an average of 74.8% males. There was an increased long-term risk of stroke in the presence of NOAF (unadjusted studies effect-sizes=1.36, 95% confidence interval, 1.12-1.65, P=0.001, adjusted studies effect-sizes=1.25, 95% confidence interval, 1.09-1.42, P=0.001). There was evidence of moderate effect variation because of heterogeneity in studies reporting unadjusted (P=0.021, I2=49.8%) and adjusted data (P=0.081, I2=49.1%), and publication bias in the latter group (Egger's test, P=0.031). Sensitivity analysis on unadjusted data by study quality, design, and surgery did not alter the effect direction.

CONCLUSIONS

Presence of NOAF in patients post-coronary artery bypass graft is associated with increased long-term risk of stroke compared with patients without NOAF. Further studies may show whether the increased risk is mediated by atrial fibrillation and whether anticoagulation reduces risk.