Anticoagulation: American College of Chest Physicians guidelines for the prevention and management of postoperative atrial fibrillation after cardiac surgery

Anticoagulation in new-onset postoperative atrial fibrillation: An analysis from the Society of Thoracic Surgeons Adult Cardiac Surgery Database

Background

New-onset postoperative atrial fibrillation (POAF) is the most common complication after cardiac surgery and is associated with increased long-term stroke and mortality. Anticoagulation has been suggested as a potential therapy, but data on safety and efficacy are scant.

Objectives

To determine the association between anticoagulation for POAF and long-term outcomes.

Methods

Adult patients with POAF after isolated coronary artery bypass surgery (CABG) were identified through the Society of Thoracic Surgeons Adult Cardiac Surgery Database and linked to the Medicare Database. Propensity-matched analyses were performed for all-cause mortality, stroke, myocardial infarction, and major bleeding for patients discharged with or without anticoagulation. Interaction between anticoagulation and CHA₂DS₂-VASc score was also assessed.

Results

Of 38,936 patients, 9861 (25%) were discharged on oral anticoagulation. After propensity score matching, discharge anticoagulation was associated with increased mortality (hazard ratio [HR] 1.16, 95% confidence interval [CI] 1.06–1.26). There was no difference in ischemic stroke between groups (HR 0.97, 95% CI 0.82–1.15), but there was significantly higher bleeding (HR 1.60, 95% CI 1.38–1.85) among those discharged on anticoagulation. Myocardial infarction was lower in the first 30 days for those discharged on anticoagulation, but this effect decreased over time. The incidence of all complications was higher for patients with CHA₂DS₂-VASc scores ≥5 compared to patients with scores of 2–4. Anticoagulation did not appear to benefit either subgroup.

Conclusion

Anticoagulation is associated with increased mortality after new-onset POAF following CABG. There was no reduction in ischemic stroke among those discharged on anticoagulation regardless of CHA₂DS₂-VASc score.

Contemporary Anticoagulation Practices for Postoperative Atrial Fibrillation: A Single Center Experience

Aims

Postoperative atrial fibrillation (POAF) is a frequent in-hospital complication after cardiac surgery. Surprisingly, despite its prevalence, management of this condition has not been well studied. One promising approach that has been evaluated in a limited number of studies is use of anticoagulation. However, the trends and patterns of real-world use of anticoagulation in POAF patients has not been systemically investigated. In this study, we aimed to determine real-world patterns of anticoagulation use for patients with POAF.

Methods

We identified 200 patients undergoing coronary artery bypass (CABG) or cardiac valve surgery at University Hospitals Cleveland Medical Center over a 2 year period beginning January 2016 with new onset POAF. We reviewed charts to verify candidacy for inclusion in the study and to extract data on anticoagulation use, adverse outcomes, and CHA₂DS₂-VASc scores.

Results

Anticoagulation use was low after CABG, but high after bioprosthetic valve surgery. The most common anticoagulant used was warfarin. Anticoagulation use was not correlated with CHA₂DS₂-VASc score or cardioversion. Stroke and mortality were higher among patients not receiving anticoagulation, however, confirmation of this finding in larger randomized studies is warranted.

Conclusions

Anticoagulation use is low after CABG and this practice does not appear to be affected by CHA₂DS₂VASc score or cardioversion. This differs with previously reported provider attitudes towards management of this condition. Stroke and mortality appear to be elevated for patients not receiving anticoagulation but further investigation is required to confirm this observation.

Atrial fibrillation post cardiac bypass surgery

Atrial fibrillation occurs in 5-40% patients after coronary artery bypass graft surgery. Atrial fibrillation increases mortality and morbidity in the post-operative period. We sought to conduct a comprehensive review of literature focusing on pathophysiology, risk factors, prevention and treatment of post coronary artery bypass graft atrial fibrillation.

Safety of Direct Oral Anticoagulants Compared to Warfarin for Atrial Fibrillation after Cardiac Surgery: A Systematic Review and Meta-Analysis

The evidence for use of direct oral anticoagulants (DOACs) in the management of post-operative cardiac surgery atrial fibrillation is limited and mostly founded on clinical trials that excluded this patient population. We performed a systematic review and meta-analysis of clinical trials and observational studies to evaluate the hypothesis that DOACs are safe compared to warfarin for the anticoagulation of patients with post-operative cardiac surgery atrial fibrillation. We searched PubMed, EMBASE, Web of Science, clinicaltrials.gov, and the Cochrane Library for clinical trials and observational studies comparing DOAC with warfarin in patients ≥18 years old who had post-cardiac surgery atrial fibrillation. Primary outcomes included stroke, systemic embolization, bleeding, and mortality. We performed a random-effects meta-analysis of all outcomes. The meta-analysis for the primary outcomes showed significantly lower risk of stroke with DOAC use (6 studies, 7143 patients, RR 0.64; 95% CI 0.50-0.81, I²: 0.0%) compared to warfarin, a trend towards lower risk of systemic embolization (4 studies, 7289 patients, RR 0.64, 95% CI 0.41-1.01, I²: 31.99%) and similar risks of bleeding (14 studies, 10182 patients, RR 0.91; 95% CI 0.74-1.10, I²: 26.6%) and mortality (12 studies, 9843 patients, relative risk [RR] 1.01; 95% CI 0.74-1.37, I²: 26.5%). Current evidence suggests that DOACs, compared to warfarin, in the management of atrial fibrillation after cardiac surgery is associated with lower risk of stroke and a strong trend for lower risk of systemic embolization, and no evidence of increased risk for hospital readmission, bleeding and mortality.

The Incidence and Natural Progression of New-Onset Postoperative Atrial Fibrillation

OBJECTIVES

This study aimed to characterize the natural progression and recurrence of new-onset postoperative atrial fibrillation (POAF) during an intermediate-term follow-up post cardiac surgery by using continuous event monitoring.

BACKGROUND

New-onset POAF is a common complication after cardiac surgery and is associated with an increased risk for stroke and all-cause mortality. Long-term data on new POAF recurrence and anticoagulation remain sparse.

METHODS

This is a single-center, prospective observational study evaluating 42 patients undergoing cardiac surgery and diagnosed during indexed admission with new-onset, transient, POAF between May 2015 and December 2019. Before discharge, all patients received implantable loop recorders for continuous monitoring. Study outcomes were the presence and timing of atrial fibrillation (AF) recurrence (first, second, and more than 2 AF recurrences), all-cause mortality, and cerebrovascular accidents. A "per-month interval" analysis of proportion of patients with any AF recurrence was assessed and reported per period of follow-up time. Kaplan-Meier analysis was used to calculate the time to first AF recurrence and report the first AF recurrence rates.

RESULTS

Forty-two patients (mean age 67.6 ± 9.6 years, 74% male, mean CHADS_2-VASc 3.5 ± 1.5) were evaluated during a mean follow-up of 1.7 ± 1.2 years. AF recurrence after discharge occurred in 30 patients (71%) and of those, 59% had AF episodes equal to or longer than 5 minutes (median AF duration at 1 month was 32 minutes [interquartile range 5.5-106], whereas median AF duration beyond 1 month was 15 minutes [interquartile range 6.3-49]). Twenty-four (80%) of the 30 patients had their first AF recurrence within the first month. During months 1 to 12 follow-up, 76% of patients had any AF recurrences (10% had their first AF recurrence, 43% had their second AF recurrence, and 23% had more than 2 AF recurrences). Beyond 1 year of follow-up, 30% of patients had any AF recurrences (10% had their first AF recurrence, 7% had their second AF recurrence, and 13% had more than 2 AF recurrences). Using Kaplan-Meier analysis, the median time to first AF recurrence was 0.83 months (95% confidence interval: 0.37 to 6) and the detection of first AF recurrence rate at 1, 3, 6, 12, 18, and 24 months was 57.1%, 59.5%, 64.3%, 64.3%, 67.3%, and 73.2%, respectively. During follow-up, there was 1 death ([-] AF recurrence) and 2 cerebrovascular accidents ([+] AF recurrence).

CONCLUSIONS

In this study of continuous monitoring with implantable loop recorders, the recurrence of AF in patients who develop transient POAF is common in the first month postoperatively. Of the patients who developed postoperative AF, 76% had any recurrence in months 1 to 12, and 30% had any recurrence beyond 1-year follow-up. Current guidelines recommend anticoagulation for POAF for 30 days. The results of this study warrant further investigation into continued monitoring and longer-term anticoagulation in this population within the context of our findings that AF duration was less than 30 minutes beyond 1 month.

Postoperative Atrial Fibrillation and Long-Term Risk of Stroke After Isolated Coronary Artery Bypass Graft Surgery

BACKGROUND

Postoperative atrial fibrillation (pAF) after coronary artery bypass grafting is a common complication. Whether pAF is associated with an increased risk of cerebrovascular accident (CVA) remains uncertain. We investigated the association between pAF and long-term risk of CVA by performing a post hoc analysis of 10-year outcomes of the ART (Arterial Revascularization Trial).

METHODS

For the present analysis, among patients enrolled in the ART (n=3102), we excluded those who did not undergo surgery (n=25), had a history of atrial fibrillation (n=45), or had no information on the incidence of pAF (n=9). The final population consisted of 3023 patients, of whom 734 (24.3%) developed pAF with the remaining 2289 maintaining sinus rhythm. Competing risk and Cox regression analyses were used to investigate the association between pAF and the risk of CVA.

RESULTS

At 10 years, the cumulative incidence of CVA was 6.3% (4.6%-8.1%) versus 3.7% (2.9%-4.5%) in patients with pAF and sinus rhythm, respectively. pAF was an independent predictor of CVA at 10 years (hazard ratio, 1.53 [95% CI, 1.06-2.23]; P=0.025) even when CVAs that occurred during the index admission were excluded from the analysis (hazard ratio, 1.47 [95% 1.02-2.11]; P=0.04).

CONCLUSIONS

Patients with pAF after coronary artery bypass grafting are at higher risk of CVA. These findings challenge the notion that pAF is a benign complication.

Update on Management of Postoperative Atrial Fibrillation After Cardiac Surgery

Postoperative atrial fibrillation (POAF) after cardiac surgery remarkably remains the most prevalent event in perioperative cardiac surgery, having great clinical and economic implications. The purpose of this study is to present recommendations based on international evidence and adapted to our clinical practice for the perioperative management of POAF. This update is based on the latest current literature derived from articles and guidelines regarding atrial fibrillation.

New-onset atrial fibrillation: an update

New-onset atrial fibrillation (NOAF) is the most common perioperative complication of heart surgery, typically occurring in the perioperative period. NOAF commonly occurs in patients who are elderly, or have left atrial enlargement, or left ventricular hypertrophy. Various factors have been identified as being involved in the development of NOAF, and numerous approaches have been proposed for its prevention and treatment. Risk factors include diabetes, obesity, and metabolic syndrome. For prevention of NOAF, β-blockers and amiodarone are particularly effective and are recommended by guidelines. NOAF can be treated by rhythm/rate control, and antithrombotic therapy. Treatment is required in patients with decreased cardiac function, a heart rate exceeding 130 beats/min, or persistent NOAF lasting for ≥ 48 h. It is anticipated that anticoagulant therapies, as well as hemodynamic management, will also play a major role in the management of NOAF. When using warfarin as an anticoagulant, its dose should be adjusted based on PT-INR. PT-INR should be controlled between 2.0 and 3.0 in patients aged < 70 years and between 1.6 and 2.6 in those aged ≥ 70 years. Rate control combined with antithrombotic therapies for NOAF is expected to contribute to further advances in treatment and improvement of survival.

Postoperative atrial fibrillation: Target for stroke prevention?

Purpose

A substantial number of patients without a history of atrial fibrillation who undergo surgery develop one or more episodes of atrial fibrillation in the first few days after the operation. We studied whether postoperative transient atrial fibrillation is a risk factor for future atrial fibrillation, stroke and death.

Method

We performed a narrative review of the literature on epidemiology, mechanisms, risk of atrial fibrillation, stroke and death after postoperative atrial fibrillation. We reviewed antithrombotic guidelines on this topic and identified gaps in current management.

Findings

Patients with postoperative atrial fibrillation are at high risk of developing atrial fibrillation in the long term. Mortality is also increased. Most, but not all observational studies report a higher risk of stroke. The optimal antithrombotic regimen for patients with postoperative atrial fibrillation has not been defined. The role of lifestyle changes and of surgical occlusion of the left atrial appendage in preventing adverse outcomes after postoperative atrial fibrillation is not established.

Conclusion

Further studies are warranted to establish the optimal strategy to prevent adverse long-term outcomes after transient, postoperative atrial fibrillation.

Cardioembolic Stroke

Cardiac embolism accounts for an increasing proportion of ischemic strokes and might multiply several-fold during the next decades. However, research points to several potential strategies to stem this expected rise in cardioembolic stroke. First, although one-third of strokes are of unclear cause, it is increasingly accepted that many of these cryptogenic strokes arise from a distant embolism rather than in situ cerebrovascular disease, leading to the recent formulation of embolic stroke of undetermined source as a distinct target for investigation. Second, recent clinical trials have indicated that embolic stroke of undetermined source may often stem from subclinical atrial fibrillation, which can be diagnosed with prolonged heart rhythm monitoring. Third, emerging evidence indicates that a thrombogenic atrial substrate can lead to atrial thromboembolism even in the absence of atrial fibrillation. Such an atrial cardiomyopathy may explain many cases of embolic stroke of undetermined source, and oral anticoagulant drugs may prove to reduce stroke risk from atrial cardiomyopathy given its parallels to atrial fibrillation. Non-vitamin K antagonist oral anticoagulant drugs have recently expanded therapeutic options for preventing cardioembolic stroke and are currently being tested for stroke prevention in patients with embolic stroke of undetermined source, including specifically those with atrial cardiomyopathy. Fourth, increasing appreciation of thrombogenic atrial substrate and the common coexistence of cardiac and extracardiac stroke risk factors suggest benefits from global vascular risk factor management in addition to anticoagulation. Finally, improved imaging of ventricular thrombus plus the availability of non-vitamin K antagonist oral anticoagulant drugs may lead to better prevention of stroke from acute myocardial infarction and heart failure.

First Diagnosis of Atrial Fibrillation at the Time of Stroke

BACKGROUND

Atrial fibrillation (AF) is a major cause of ischemic stroke. Individuals with undiagnosed AF lack the stroke protection afforded by oral anticoagulants. We obtained a contemporary estimate of the percentage of AF patients newly diagnosed at the time of stroke.

METHODS

We identified patients admitted to the Massachusetts General Hospital (MGH) from January 1, 2010 to December 31, 2013 with acute ischemic stroke and either previously or newly diagnosed AF using hospital stroke registry data and stroke and AF ICD-9 code searches of hospital databases. Reviewers categorized AF as previously known or newly diagnosed, and collected comorbidity and outcome data. To confirm AF as newly diagnosed, we searched patients' pre-event electronic medical records (EMRs) for AF terms.

RESULTS

AF was considered newly diagnosed in 156/856 patients (18%; 95% CI 16-21). In 136/156 cases, AF was diagnosed using 12-lead EKG, telemetry, or rhythm strips. New AF strokes had a median NIH stroke scale of 12; 60% had mRankin ≥3 at discharge, including 15% deaths. Pre-stroke CHA2DS2-VASc score was ≥2 in 89%. About half (76/156) had prior records in the MGH EMR. Evidence of pre-stroke AF, often peri-procedural, was found in 8/76, but the AF diagnosis was not carried forward.

CONCLUSIONS

In this contemporary cohort, nearly one in 5 AF-related strokes occurred without a pre-stroke AF diagnosis. AF was readily diagnosed using standard rhythm monitoring. The vast majority of patients with newly diagnosed AF were at high enough pre-stroke risk to merit anticoagulation. In conclusion, our findings support screening for AF before stroke. Patients with past transient AF may merit more intensive screening.

PR-Interval Components and Atrial Fibrillation Risk (from the Atherosclerosis Risk in Communities Study)

Reports on the association between the PR-interval and atrial fibrillation (AF) are conflicting. We hypothesized that inconsistencies stem from that fact that the PR-interval represents a composite of several distinct components. We examined the associations of the PR-interval and its components (P-wave onset to P-wave peak duration, P-wave peak to P-wave end duration, and PR-segment) with incident AF in 14,924 participants (mean age 54 ± 5.8 years; 26% black; 55% women) from the Atherosclerosis Risk In Communities study. The PR-interval and its components were automatically measured at baseline (1987 to 1989) from standard 12-lead electrocardiograms. PR-interval >200 ms was considered prolonged and values above the ninety-fifth percentile defined abnormal PR-interval components. AF was ascertained during follow-up through December 31, 2010. Over a median follow-up of 21.2 years, 1,985 participants (13%) developed AF. Prolonged PR-interval was associated with an increased risk of AF (hazard ratio [HR] 1.19, 95% confidence interval [CI] 1.02 to 1.40). However, PR-interval components showed varying levels of association with AF (P-wave onset to P-wave peak duration: HR 1.57, 95% CI 1.31 to 1.88; P-wave peak to P-wave end duration: HR 1.20, 95% CI 0.99 to 1.46; and PR-segment: HR 1.05, 95% CI 0.85 to 1.29). In addition, the components of the PR-interval had weak-to-moderate correlation with each other (correlation r ranged from -0.44 to 0.06). In conclusion, our findings suggest the PR-interval represents a composite of distinct components that are not uniformly associated with AF. Without considering the contribution of each component, inconsistent associations between the PR-interval and AF are inevitable.

Perioperative management of adult patients with a history of stroke or transient ischaemic attack undergoing elective non-cardiac surgery

It is increasingly common for physicians and anaesthetists to be asked for advice in the medical management of surgical patients who have an incidental history of stroke or transient ischaemic attack (TIA). Advising clinicians requires an understanding of the common predictors, outcomes and management of perioperative stroke. The most important predictor of perioperative stroke is a previous history of stroke, and outcomes associated with such an event are extremely poor. The perioperative management of this patient group needs careful consideration to minimise the thrombotic risk and a comprehensive, individualised approach is crucial. Although there is literature supporting the management of such patients undergoing cardiac surgery, evidence is lacking in the setting of non-cardiac surgical intervention. This article reviews the current evidence and provides a pragmatic interpretation to inform the perioperative management of patients with a history of stroke and/or TIA presenting for elective non-cardiac surgery.

Advanced interatrial block and ischemic stroke: The Atherosclerosis Risk in Communities Study

OBJECTIVE

Given that recent reports have suggested left atrial disease to be an independent risk factor for ischemic stroke, we sought to examine if advanced interatrial block (aIAB) is an independent stroke risk factor.

METHODS

We examined the association between aIAB and incident ischemic stroke in 14,716 participants (mean age 54 ± 5.8 years; 55% female; 26% black) from the Atherosclerosis Risk in Communities Study (ARIC). Cases of aIAB were identified from digital ECGs recorded during the baseline ARIC visit (1987-1989) and the first 3 follow-up study visits (1990-1992, 1993-1995, and 1996-1998). Adjudicated ischemic stroke events were ascertained through December 31, 2010.

RESULTS

There were 266 (1.8%) participants who had evidence of aIAB. Over a median follow-up of 22 years, 916 (6.2%) ischemic stroke events were detected. The incidence rate (per 1,000 person-years) of ischemic stroke among those with aIAB (incidence rate 8.05, 95% confidence interval [CI] 5.7, 11.4) was more than twice the rate in those without aIAB (incidence rate 3.14, 95% CI 2.94, 3.35). In a multivariable Cox regression analysis adjusted for stroke risk factors and potential confounders, aIAB was associated with an increased risk of ischemic stroke (hazard ratio 1.63, 95% CI 1.13, 2.34). The results were consistent across subgroups of participants stratified by age, sex, and race.

CONCLUSIONS

In the ARIC, aIAB was associated with incident ischemic stroke, which strengthens the hypothesis that left atrial disease should be considered an independent stroke risk factor.

Electrocardiographic Advanced Interatrial Block and Atrial Fibrillation Risk in the General Population

Although advanced interatrial block (aIAB) is an established electrocardiographic phenotype, its prevalence, incidence, and prognostic significance in the general population are unclear. We examined the prevalence, incidence, and prognostic significance of aIAB in 14,625 (mean age = 54 ± 5.8 years; 26% black; 55% female) participants from the Atherosclerosis Risk in Communities (ARIC) study. aIAB was detected from digital electrocardiograms recorded during 4 study visits (1987 to 1989, 1990 to 1992, 1993 to 1995, and 1996 to 1998). Risk factors for the development of aIAB were examined using multivariable Poisson regression models with robust variance estimates. Cox regression was used to compute hazard ratios and 95% CIs for the association between aIAB, as a time-dependent variable, and atrial fibrillation (AF). AF was ascertained from study electrocardiogram data, hospital discharge records, and death certificates thorough 2010. A total of 69 participants (0.5%) had aIAB at baseline, and 193 (1.3%) developed aIAB during follow-up. The incidence for aIAB was 2.27 (95% CI 1.97 to 2.61) per 1,000 person-years. Risk factors for aIAB development included age, male gender, white race, antihypertensive medication use, low-density lipoprotein cholesterol, body mass index, and systolic blood pressure. In a Cox regression analysis adjusted for sociodemographics, cardiovascular risk factors, and potential confounders, aIAB was associated with an increased risk for AF (hazard ratio 3.09, 95% CI 2.51 to 3.79). In conclusion, aIAB is not uncommon in the general population. Risk factors for developing aIAB are similar to those for AF, and the presence of aIAB is associated with an increased risk for AF.

Routine postoperative care of patients undergoing coronary artery bypass grafting on cardiopulmonary bypass

The postoperative course of a patient undergoing cardiac surgery (CS) is dictated by a largely predictable set of interactions between disease-specific and therapeutic factors. ICU personnel need to quickly develop a detailed understanding of the patient's current status and how critical care resources can be used to promote further recovery and eventual independence from external support. The goal of this article is to describe a typical operative and postoperative course, with emphasis on the latter, and the diagnostic and therapeutic options necessary for the proper care of these patients. This paper will focus on coronary artery bypass grafting as a model for understanding the course of CS patients; however, many of the principles discussed are applicable to most cardiac surgery patients.

Perioperative stroke

PURPOSE

Perioperative stroke is associated with significant morbidity and mortality, with an incidence that may be underappreciated. In this review, we examine the significance, pathophysiology, risk factors, and evidence-based recommendations for the prevention and management of perioperative stroke.

SOURCE

This is a narrative review based on literature from the PubMed database regarding perioperative stroke across a broad surgical population. The Society for Neuroscience in Anesthesiology and Critical Care recently published evidence-based recommendations for perioperative management of patients at high risk for stroke; these recommendations were analyzed and incorporated into this review.

PRINCIPAL FINDINGS

The incidence of overt perioperative stroke is highest in patients presenting for cardiac and major vascular surgery, although preliminary data suggest that the incidence of covert stroke may be as high as 10% in non-cardiac surgery patients. The pathophysiology of perioperative stroke involves different pathways. Thrombotic stroke can result from increased inflammation and hypercoagulability; cardioembolic stroke can result from disease states such as atrial fibrillation, and tissue hypoxia from anemia can result from the combination of anemia and beta-blockade. Across large-scale database studies, common risk factors for perioperative stroke include advanced age, history of cerebrovascular disease, ischemic heart disease, congestive heart failure, atrial fibrillation, and renal disease. Recommendations for prevention and management of perioperative stroke are evolving, though further work is needed to clarify the role of proposed modifiable risk factors such as perioperative anticoagulation, antiplatelet therapy, appropriate transfusion thresholds, and perioperative beta-blockade.

CONCLUSIONS

Perioperative stroke carries a significant clinical burden. The incidence of perioperative stroke may be higher than previously recognized, and there are diverse pathophysiologic mechanisms. There are many opportunities for further investigation of the pathophysiology, prevention, and management of perioperative stroke.

Electrocardiographic left atrial abnormality and stroke subtype in the atherosclerosis risk in communities study

OBJECTIVE

The aim of this study was to assess the relationship between abnormally increased P-wave terminal force in lead V1 , an electrocardiographic (ECG) marker of left atrial abnormality, and incident ischemic stroke subtypes. We hypothesized that associations would be stronger with nonlacunar stroke, given that we expected left atrial abnormality to reflect the risk of thromboembolism rather than in situ cerebral small-vessel occlusion.

METHODS

Our cohort comprised 14,542 participants 45 to 64 years of age prospectively enrolled in the Atherosclerosis Risk in Communities study and free of clinically apparent atrial fibrillation (AF) at baseline. Left atrial abnormality was defined as PTFV1 >4,000μV*ms. Outcomes were adjudicated ischemic stroke, nonlacunar (including cardioembolic) ischemic stroke, and lacunar stroke.

RESULTS

During a median follow-up period of 22 years (interquartile range, 19-23 years), 904 participants (6.2%) experienced a definite or probable ischemic stroke. A higher incidence of stroke occurred in those with baseline left atrial abnormality (incidence rate per 1,000 person-years, 6.3; 95% confidence interval [CI]: 5.4-7.4) than in those without (incidence rate per 1,000 person-years, 2.9; 95% CI: 2.7-3.1; p < 0.001). In Cox regression models adjusted for potential confounders and incident AF, left atrial abnormality was associated with incident ischemic stroke (hazard ratio [HR]: 1.33; 95% CI: 1.11-1.59). This association was limited to nonlacunar stroke (HR, 1.49; 95% CI: 1.07-2.07) as opposed to lacunar stroke (HR, 0.89; 95% CI: 0.57-1.40).

INTERPRETATION

We found an association between ECG-defined left atrial abnormality and subsequent nonlacunar ischemic stroke. Our findings suggest that an underlying atrial cardiopathy may cause left atrial thromboembolism in the absence of recognized AF.

Stroke associated with coronary artery bypass grafting

While coronary artery bypass grafting (CABG) has been playing a significant role in the revascularization for ischemic heart disease, neurological complications associated with CABG have been a primary concern. Stroke, although the incidence is low, is one of the most devastating complication of CABG. Many studies have identified the risk factors for stroke with CABG, such as prior stroke, carotid artery stenosis, aortic atherosclerosis, atrial fibrillation and cardiopulmonary bypass. Various rational approaches focusing on individual risk factor have been proposed for the stroke. Prophylactic carotid revascularization is an important strategy, and the diagnosis of carotid stenosis has to be established correctly. Prevention of emboli from aortic plaque is also an essential issue. Intraoperative monitoring with transesophageal or epiaortic ultrasound is useful to identify mobile atheromatous plaques and to select appropriate aortic manipulations. Maintenance of cerebral blood flow and blood pressure during cardiopulmonary bypass might be critical issues. Besides, there are conflicting two opinions regarding off-pump CABG; one supports an efficiency for the prevention of stroke while the other advocates no effect. This discrepancy might be explained by the difference of the risk of stroke in the population of the individual study and by the variation of the percentage of aortic clamping or aortic anastomosis in each study. Pharmaceutical therapies such as statin, preventive medication for atrial fibrillation, or antiplatelet are promising methods. Although it is hard to decrease the incidence of the stroke with any single countermeasure, sustained effort should be continued to overcome the stroke associated with CABG.

Long-term outcomes of secondary atrial fibrillation in the community: the Framingham Heart Study

BACKGROUND

Guidelines have proposed that atrial fibrillation (AF) can occur as an isolated event, particularly when precipitated by a secondary, or reversible, condition. However, knowledge of long-term AF outcomes after diagnosis during a secondary precipitant is limited.

METHODS AND RESULTS

In 1409 Framingham Heart Study participants with new-onset AF, we examined associations between first-detected AF episodes occurring with and without a secondary precipitant and both long-term AF recurrence and morbidity. We selected secondary precipitants based on guidelines (surgery, infection, acute myocardial infarction, thyrotoxicosis, acute alcohol consumption, acute pericardial disease, pulmonary embolism, or other acute pulmonary disease). Among 439 patients (31%) with AF diagnosed during a secondary precipitant, cardiothoracic surgery (n=131 [30%]), infection (n=102 [23%]), noncardiothoracic surgery (n=87 [20%]), and acute myocardial infarction (n=78 [18%]) were most common. AF recurred in 544 of 846 eligible individuals without permanent AF (5-, 10-, and 15-year recurrences of 42%, 56%, and 62% with versus 59%, 69%, and 71% without secondary precipitants; multivariable-adjusted hazard ratio, 0.65 [95% confidence interval, 0.54-0.78]). Stroke risk (n=209/1262 at risk; hazard ratio, 1.13 [95% confidence interval, 0.82-1.57]) and mortality (n=1098/1409 at risk; hazard ratio, 1.00 [95% confidence interval, 0.87-1.15]) were similar between those with and without secondary precipitants, although heart failure risk was reduced (n=294/1107 at risk; hazard ratio, 0.74 [95% confidence interval, 0.56-0.97]).

CONCLUSIONS

AF recurs in most individuals, including those diagnosed with secondary precipitants. Long-term AF-related stroke and mortality risks were similar between individuals with and without secondary AF precipitants. Future studies may determine whether increased arrhythmia surveillance or adherence to general AF management principles in patients with reversible AF precipitants will reduce morbidity.

Atrial fibrillation at mid-term after bioprosthetic aortic valve replacement – implications for anti-thrombotic therapy

BACKGROUND

Little is known about mid-term (3-month) postoperative atrial fibrillation (MT-POAF) in patients treated with bioprosthetic aortic valve replacement (BAVR). The aim of this study was to describe the natural history, identify the predictors and investigate the potential consequences in terms of anti-thrombotic therapy.

METHODS AND RESULTS

During a longitudinal, prospective study, 219 patients were treated with BAVR early (7 days) and at mid-term postoperatively (30 and 90 days). POAF was monitored and risk factors were identified on logistic regression analysis. History of previous AF (OR, 3.08; 95% CI: 1.35-6.98), early POAF (OR, 5.93; 95% CI: 2.96-11.8), and BMI (per 5 kg/m(2): OR, 1.46; 95% CI: 1.03-2.09), were independent predictors for MT-POAF whereas sex, age and Euroscore were not. Results were identical when restricted to the 176 patients free from preoperative AF. In this subgroup, 36 patients (20.4%) had MT-POAF; 33 out of 174 (18.7%) would have required anticoagulation (CHA2DS2VASc score ≥ 1). Conversely, patients with BMI <27.7 and sinus rhythm at early follow-up had a very low risk of MT-POAF (OR, 0.16; 95% CI: 0.06-0.42).

CONCLUSIONS

There was a higher than expected occurrence of MT-POAF in patients treated with BAVR, particularly in overweight patients with early POAF. This raises the question of implementing an anti-thrombotic therapy in these patients at higher risk of delayed atrial arrhythmia.

Postoperative atrial fibrillation: incidence, mechanisms, and clinical correlates

Atrial fibrillation is the most commonly encountered arrhythmia after cardiac surgery. Although usually self-limiting, it represents an important predictor of increased patient morbidity, mortality, and health care costs. Numerous studies have attempted to determine the underlying mechanisms of postoperative atrial fibrillation (POAF) with varied success. A multifactorial pathophysiology is hypothesized, with inflammation and postoperative β-adrenergic activation recognized as important contributing factors. The management of POAF is complicated by a paucity of data relating to the outcomes of different therapeutic interventions in this population. This article reviews the literature on epidemiology, mechanisms, and risk factors of POAF, with a subsequent focus on the therapeutic interventions and guidelines regarding management.

Perioperative atrial fibrillation and the long-term risk of ischemic stroke

IMPORTANCE

Clinically apparent atrial fibrillation increases the risk of ischemic stroke. In contrast, perioperative atrial fibrillation may be viewed as a transient response to physiological stress, and the long-term risk of stroke after perioperative atrial fibrillation is unclear.

OBJECTIVE

To examine the association between perioperative atrial fibrillation and the long-term risk of stroke.

DESIGN, SETTING, AND PARTICIPANTS

Retrospective cohort study using administrative claims data on patients hospitalized for surgery (as defined by surgical diagnosis related group codes), and discharged alive and free of documented cerebrovascular disease or preexisting atrial fibrillation from nonfederal California acute care hospitals between 2007 and 2011. Patients undergoing cardiac vs other types of surgery were analyzed separately.

MAIN OUTCOMES AND MEASURES

Previously validated diagnosis codes were used to identify ischemic strokes after discharge from the index hospitalization for surgery. The primary predictor variable was atrial fibrillation newly diagnosed during the index hospitalization, as defined by previously validated present-on-admission codes. Patients were censored at postdischarge emergency department encounters or hospitalizations with a recorded diagnosis of atrial fibrillation.

RESULTS

Of 1,729,360 eligible patients, 24,711 (1.43%; 95% CI, 1.41%-1.45%) had new-onset perioperative atrial fibrillation during the index hospitalization and 13,952 (0.81%; 95% CI, 0.79%-0.82%) experienced a stroke after discharge. At 1 year after hospitalization for cardiac surgery, cumulative rates of stroke were 0.99% (95% CI, 0.81%-1.20%) in those with perioperative atrial fibrillation and 0.83% (95% CI, 0.76%-0.91%) in those without atrial fibrillation. At 1 year after noncardiac surgery, cumulative rates of stroke were 1.47% (95% CI, 1.24%-1.75%) in those with perioperative atrial fibrillation and 0.36% (95% CI, 0.35%-0.37%) in those without atrial fibrillation. In a Cox proportional hazards analysis accounting for potential confounders, perioperative atrial fibrillation was associated with subsequent stroke both after cardiac surgery (hazard ratio, 1.3; 95% CI, 1.1-1.6) and noncardiac surgery (hazard ratio, 2.0; 95% CI, 1.7-2.3). The association was significantly stronger for perioperative atrial fibrillation after noncardiac vs cardiac surgery (P < .001 for interaction).

CONCLUSIONS AND RELEVANCE

Among patients hospitalized for surgery, perioperative atrial fibrillation was associated with an increased long-term risk of ischemic stroke, especially following noncardiac surgery.

Anticoagulation strategies for the management of postoperative atrial fibrillation

Patients undergoing thoracic and cardiac procedures are at the highest risk for postoperative atrial fibrillation (POAF). POAF is associated with poor short-term and long-term outcomes, including high rates of early and late stroke, and late mortality. Patients with POAF that persists for longer than 48 hours should be anticoagulated on warfarin. Three new oral anticoagulants are available for the treatment of nonvalvular atrial fibrillation and have been found to be as efficacious or superior to warfarin in the prevention of stroke in high-risk patients, with similar to lower rates of major bleeding, and lower rates of intracranial hemorrhage.

Mapping and ablation of autonomic ganglia in prevention of postoperative atrial fibrillation in coronary surgery: MAAPPAFS atrial fibrillation randomized controlled pilot study

BACKGROUND

Postoperative atrial fibrillation (POAF) remains common after coronary artery bypass grafting (CABG). Limited efforts to intervene on cardiac autonomic ganglionic plexi (AGP) during surgery show mixed results. In this pilot study, we evaluated the safety and feasibility of map-guided ablation of AGPs during isolated CABG in the prevention of POAF.

METHODS

In this pilot study, patients undergoing isolated CABG were randomized into an intervention group (mapping and ablation of AGP [AGP+] group), and a control group (no mapping and ablation [AGP-] group). Using high-frequency stimulation, active AGPs were identified and ablated intraoperatively using radiofrequency. Continuous rhythm monitoring, serum electrolytes, postoperative medications, and postoperative complications were recorded until discharge.

RESULTS

Randomization of 47 patients (24 AGP+ and 23 AGP-) resulted in similar baseline characteristics, past medical history, and preoperative medication use. The intervention added a median of 14 minutes to the operative time. The incidence of POAF, mean time in POAF, and median length of stay in hospital were: AGP+ 21% vs AGP- 30%; AGP+ 298 minutes vs AGP- 514 minutes; AGP+ 5 days vs AGP- 6 days; respectively). Postoperative complications, medication use, and daily serum electrolyte profiles were similar in both groups.

CONCLUSIONS

This pilot study demonstrated the safety and feasibility of mapping and ablation of AGP during CABG with minimal added operative time. Results further suggest a potentially clinically significant effect on POAF. A multicentre trial is warranted.

A prospective randomized controlled trial on the incidence and predictors of late-phase postoperative atrial fibrillation up to 30 days and the preventive value of biatrial pacing

BACKGROUND

Postoperative atrial fibrillation (POAF) is considered to be a transient arrhythmia in the first week after cardiac surgery.

OBJECTIVE

To determine the 30-day incidence and predictors of POAF and the value of postoperative overdrive biatrial pacing in the prevention of POAF.

METHODS

Patients (n = 148) without a history of atrial fibrillation undergoing aortic valve replacement or coronary artery bypass graft (CABG) were randomized into a pacing group (n = 75) and a control group. Patients were treated with standardized sotalol postoperatively. Rhythm was continuously monitored for 30 days by a transtelephonic event recorder.

RESULTS

POAF occurred in 73 (49.3%) patients, of whom 60 (40.5%) patients showed POAF during postoperative days (PODs) 0-5 and 37 (25%) patients during PODs 6-30. Prolonged aortic cross-clamp time was an important univariate predictor of 30-day and of late POAF (PODs 6-30; P = .017 and P = .03, respectively). Best-fit model analysis using 15 predetermined risk factors for POAF showed different positive interactive effects for early POAF (ie, baseline C-reactive protein levels with a history of myocardial infarction or low body mass index) and late POAF (ie, high body mass index, diabetes mellitus, baseline C-reactive protein, early POAF, creatinine levels, type of operation, smoking, and male gender). Biatrial pacing reduced the late POAF incidence in patients with aortic cross-clamp time >50 minutes (P = .006).

CONCLUSION

POAF is not limited to the first week after cardiac surgery but also occurs frequently in the postoperative month. It is desirable to regularly follow patients with POAF for atrial fibrillation recurrences after discharge.

Perioperative stroke

It is increasingly recognized that one can identify a higher risk patient for perioperative stroke. The risk of stroke around the time of operative procedures is fairly substantial and it is recognized that patients initially at risk for vascular events are those most likely to have this risk heightened by invasive procedures. Higher risk patients include those of advanced age and there is a cumulative risk, over time, of coexistent hypertension, atherosclerosis, diabetes mellitus, cardiac disease and clotting disorders. There are a number of possible mechanisms associated with the procedure (e.g., preoperative hypercoagulability, holding of antithrombic therapy at the time of the procedure and cardiac arrhythmia) that can promote a thrombo-embolic event. Examples of these include: direct mechanical trauma to extracranial vessels related to operations on the head and neck; and vascular injury as a consequence of vascular and innovative endovascular procedures affecting the cerebral circulation (e.g., carotid endarterectomy, extracranial or intracranial angioplasty with stenting, and use of the MERCI clot retrieval device), as well as various endovascular methods that have been developed to obliterate cerebral aneurysms and arteriovenous malformations as an alternative to surgical clipping and surgical resection, respectively.

Management strategies in cardiac surgery for postoperative atrial fibrillation: contemporary prophylaxis and futuristic anticoagulant possibilities

With more than a third of patients expected to endure the arrhythmia at any given time point, atrial fibrillation after cardiac surgery becomes a vexing problem in the postoperative care of cardiac surgery patients. The impact on patient care covers a spectrum from the more common clinically insignificant sequelae to debilitating embolic events. Despite this, postoperative atrial fibrillation generally masquerades as being insignificant, or at most as an anticipated inherent risk, merely extending one's hospital stay by a few days. As an independent risk factor for stroke, early and late mortality, and being a multibillion dollar strain on the healthcare system annually, postoperative atrial fibrillation is far more flagrant than a mere inherent risk. It is a serious medical quandary, which is not recognized as such. Though complete prevention is unrealistic, a step-wise treatment strategy that incorporates multiple preventative modalities can significantly reduce the impact of postoperative atrial fibrillation on patient care. The aims of this review are to present a brief overview of the arrhythmia's etiology, risk factors, and preventative strategies to reduce associated morbidities. Newer anticoagulants and the potential role of these drugs on future treatment paradigms are also discussed.

Post-operative Atrial Fibrillation - Pathophysiology, Treatment and Prevention

Atrial fibrillation occurring after cardiac surgery has been the subject of intensive research over the past decades. However, the incidence remains high, despite numerous preventive and treatment strategies. In addition, several reports show that the impact of post-operative atrial fibrillation (POAF) is high. It is an independent risk factor for mortality after several years. These findings make clear that the pathophysiology of POAF is not fully understood and POAF-associated risks to some extent might be underestimated. On the one hand, excessive triggers during the acute post operative phase after cardiac surgery might initiate AF even in atria with low vulnerability. On the other hand, many patients undergoing surgery have an atrial substrate at the time of operation promoting AF not only in the post-operative phase but also in the days and weeks thereafter. Progress in our understanding of the AF mechanisms in general has provided valuable insights into processes involved in atrial structural remodeling due to advanced age, hypertension, obesity, and congestive heart failure. These patient characteristics strongly contribute to cardiac disease, predict POAF and likely have an impact on the risk of thrombus formation in the weeks and months after cardiac surgery. For a better understanding of the mechanisms involved, it is important to not only recognize the occurrence of POAF by continuous monitoring after surgery, but also to identity the extent of atrial vulnerability to AF in these patients.

Management of postoperative atrial fibrillation

The impact of postoperative atrial fibrillation (PAF) on patient outcomes has prompted intense investigation into the optimal methods for prevention and treatment of this complication. In the prevention of PAF, β-blockers and amiodarone are particularly effective and are recommended by guidelines. However, their use requires caution due to the possibility of drug-related adverse effects. Aside from these risks, perioperative prophylactic treatment with statins seems to be effective for preventing PAF and is associated with a low incidence of adverse effects. PAF can be treated by rhythm control, heart-rate control, and antithrombotic therapy. For the purpose of heart rate control, β-blockers, calcium-channel antagonists, and amiodarone are used. In patients with unstable hemodynamics, cardioversion may be performed for rhythm control. Antithrombotic therapy is used in addition to heart-rate maintenance therapy in cases of PAF >48-h duration or in cases with a history of cerebrovascular thromboembolism. Anticoagulation is the first choice for antithrombotic therapy, and anticoagulation management should focus on maintaining international normalized ratio (INRs) in the 2.0–3.0 range in patients <75 years of age, whereas prothrombin-time INR should be controlled to the 1.6–2.6 range in patients ≥75 years of age. In the future, dabigatran could be used for perioperative management of PAF, because it does not require regular monitoring and has a quick onset of action with short serum half-life. Preventing PAF is an important goal and requires specific perioperative management as well as other approaches. PAF is also associated with lifestyle-related diseases, which emphasizes the ongoing need for appropriate lifestyle management in individual patients.

Temporal pattern of strokes after on-pump and off-pump coronary artery bypass graft surgery

BACKGROUND

The incidence of strokes has not decreased after coronary artery bypass graft surgery (CABG). The purpose of this study is to identify incidence, risk factors, and temporal pattern of strokes after on-pump and off-pump CABG.

METHODS

We analyzed 2,516 consecutive patients who underwent first elective isolated CABG. The primary endpoint was strokes within 30 days. The temporal onset of the deficits was classified by consensus as either an "early stroke," which is present just after emergence from anesthesia, or a "delayed stroke," which is present after first awaking from surgery without a neurologic deficit.

RESULTS

More than half of strokes (29 of 46; 63%) were delayed strokes. Patients undergoing off-pump CABG had significantly lower risk of early stroke (0.1% versus 1.1%, p = 0.0009), whereas the incidence of delayed strokes was not different significantly (0.9% versus 1.4%, p = 0.3484) between patients undergoing on-pump and off-pump CABG. In multivariate analyses, undergoing off-pump CABG was an independent protective factor for all strokes (relative risk 0.29, 95% confidence interval: 0.14 to 0.56, p = 0.0005) and early strokes (relative risk 0.05, 95% confidence interval: 0.003 to 0.24, p < 0.0001), but it was not an independent protective factor for delayed strokes (relative risk 0.54, 95% confidence interval: 0.24 to 1.17, p = 0.1210).

CONCLUSIONS

Undergoing off-pump CABG reduces the incidence of perioperative stroke mainly by minimizing early strokes; however, the risk of delayed strokes is not different between patients undergoing on-pump and off-pump CABG.

Clinical review: treatment of new-onset atrial fibrillation in medical intensive care patients--a clinical framework

Atrial fibrillation occurs frequently in medical intensive care unit patients. Most intensivists tend to treat this rhythm disorder because they believe it is detrimental. Whether atrial fibrillation contributes to morbidity and/or mortality and whether atrial fibrillation is an epiphenomenon of severe disease, however, are not clear. As a consequence, it is unknown whether treatment of the arrhythmia affects the outcome. Furthermore, if treatment is deemed necessary, it is not known what the best treatment is. We developed a treatment protocol by searching for the best evidence. Because studies in medical intensive care unit patients are scarce, the evidence comes mainly from extrapolation of data derived from other patient groups. We propose a treatment strategy with magnesium infusion followed by amiodarone in case of failure. Although this strategy seems to be effective in both rhythm control and rate control, the mortality remained high. A randomised controlled trial in medical intensive care unit patients with placebo treatment in the control arm is therefore still defendable.

Atrial fibrillation and the postoperative cardiac surgery patient

Atrial fibrillation (AF) is the most common dysrhythmia that affects adults, with an estimated 2.2 million people diagnosed in the United States and 4.5 million in the European Union. The development of postoperative AF is associated with negative patient outcomes. This article provides critical care nurses with an understanding of the etiology of AF, risk factors associated with the development of it, and current treatment options for this dysrhythmia. In addition to the medical management of AF, an overview of preventive protocols, nursing implications, and patient education is provided.

Avoiding pitfalls of anticoagulation therapy

Antithrombotic therapy poses a significant risk of litigation owing to the risk of devastating outcomes from both the condition for which the therapy is necessary and the therapy itself. Using a case-based approach, this article illustrates how evidence-based guidelines, documentation, and patient communication can potentially reduce the likelihood of errors associated with antithrombotic therapy.