CHADS2 score predicts atrial fibrillation following cardiac surgery

Predicting atrial fibrillation after cardiac surgery: a scoping review of associated factors and systematic review of existing prediction models

INTRODUCTION

Postoperative atrial fibrillation (POAF) is common after cardiac surgery and associated with increased hospital length of stay, patient morbidity and mortality. We aimed to identify factors associated with POAF and evaluate the accuracy of available POAF prediction models.

METHODS

We screened articles from Ovid MEDLINE® and PubMed Central® (PMC) and included studies that evaluated risk factors associated with POAF or studies that designed or validated POAF prediction models. We only included studies in cardiac surgical patients with sample size n ⩾ 50 and a POAF outcome group ⩾20. We summarised factors that were associated with POAF and assessed prediction model performance by reviewing reported calibration and discriminative ability.

RESULTS

We reviewed 232 studies. Of these, 142 fulfilled the inclusion criteria. Age was frequently found to be associated with POAF, while most other variables showed contradictory findings, or were assessed in few studies. Overall, 15 studies specifically developed and/or validated 12 prediction models. Of these, all showed poor discrimination or absent calibration in predicting POAF in externally validated cohorts.

CONCLUSIONS

Except for age, reporting of factors associated with POAF is inconsistent and often contradictory. Prediction models have low discrimination, missing calibration statistics, are at risk of bias and show limited clinical applicability. This suggests the need for studies that prospectively collect AF relevant data in large cohorts and then proceed to validate findings in external data sets.

The concentration of resistin in perivascular adipose tissue after CABG and postoperative atrial fibrillation

BACKGROUND

Postoperative atrial fibrillation occurs in up to 30% of patients after coronary artery bypass graft (CABG) and its cause is unknown. The aim of the study was to evaluate whether concentration of resistin in surrounding coronary artery perivascular adipose tissue (PVAT) is related to postoperative atrial fibrillation occurrence.

METHODS

A total number of 46 patients (35 male, 11 female; median age 66.5) were qualified for elective CABG. Medical history, laboratory test results and echocardiographic parameters were noted. Patients were monitored up to 3 days after CABG and then were divided into groups with and without postoperative atrial fibrillation occurrence. Fragments of PVAT were collected intra-operatively: near the left anterior descending artery and main left coronary artery. The concentration of resistin was determined by Human Resistin Quantikine ELISA Kit and expressed as ng/g. A multivariate stepwise logistic regression analysis was performed to find variables related to postoperative atrial fibrillation occurrence.

RESULTS

Postoperative atrial fibrillation occurred in 14 (30.4%) patients. The patients with and without postoperative atrial fibrillation were similar in age, gender, epicardial adipose tissue thickness and laboratory parameters. The concentration of resistin in PVAT near the left main coronary artery was significantly higher in patients with postoperative atrial fibrillation than in those without the complication (P = 0.03). In the multivariate stepwise logistic regression analysis the concentration of resistin above cut-off point 54 ng/g in PVAT near left main coronary artery was independently related to postoperative atrial fibrillation occurrence (OR: 7.7; 95% CI:1.4-42.2 p = 0.02).

CONCLUSIONS

The higher concentrations of resistin in PVAT near the left main coronary artery which is located close to the left atrium are associated with postoperative atrial fibrillation.

Clinical Risk Factors for Postoperative Atrial Fibrillation among Patients after Cardiac Surgery

BACKGROUND

Postoperative atrial fibrillation (POAF) is a common arrhythmia following cardiac surgery and is associated with increased health-care costs, complications, and mortality. The etiology of POAF is incompletely understood and its prediction remains suboptimal. Using data from published studies, we performed a systemic review and meta-analysis to identify preoperative clinical risk factors associated with patients at increased risk of POAF.

METHODS

A systematic search of PubMed, MEDLINE, and EMBASE databases was performed.

RESULTS

Twenty-four studies that reported univariate analysis results regarding POAF risk factors, published from 2001 to May 2017, were included in this meta-analysis with a total number of 36,834 subjects. Eighteen studies were performed in the United States and Europe and 16 studies were prospective cohort studies. The standardized mean difference (SMD) between POAF and non-POAF groups was significantly different (reported as [SMD: 95% confidence interval, CI]) for age (0.55: 0.47-0.63), left atrial diameter (0.45: 0.15-0.75), and left ventricular ejection fraction (0.30: 0.14-0.47). The pooled odds ratios (ORs) (reported as [OR: 95% CI]) demonstrated that heart failure (1.56: 1.31-1.96), chronic obstructive pulmonary disease (1.36: 1.13-1.64), hypertension (1.29: 1.12-1.48), and myocardial infarction (1.18: 1.05-1.34) were significant predictors of POAF incidence, while diabetes was marginally significant (1.06: 1.00-1.13).

CONCLUSION

The present analysis suggested that older age and history of heart failure were significant risk factors for POAF consistently whether the included studies were prospective or retrospective datasets.

Postoperative atrial fibrillation following cardiac surgery: a persistent complication

Postoperative atrial fibrillation (POAF) is a common, expensive and potentially morbid complication following cardiac surgery. POAF occurs in around 35% of cardiac surgery cases and has a peak incidence on postoperative day 2. Patients who develop POAF incur on average $10 000-$20 000 in additional hospital treatment costs, 12-24 h of prolonged ICU time, and an additional 2 to 5 days in the hospital. POAF has been identified as an independent predictor of numerous adverse outcomes, including a 2- to 4-fold increased risk of stroke, reoperation for bleeding, infection, renal or respiratory failure, cardiac arrest, cerebral complications, need for permanent pacemaker placement, and a 2-fold increase in all-cause 30-day and 6-month mortality. The pathogenesis of POAF is incompletely understood but likely involves interplay between pre-existing physiological components and local and systemic inflammation. POAF is associated with numerous risk factors including advanced age, pre-existing conditions that cause cardiac remodelling and certain non-cardiovascular conditions. Clinical management of POAF includes both prophylactic and therapeutic measures, although the efficacy of many interventions remains in question. This review provides a comprehensive and up-to-date summary of the pathogenesis of POAF, outlines current clinical guidelines for POAF prophylaxis and management, and discusses new avenues for further investigation.

Performance and validation of a simplified postoperative atrial fibrillation risk score

BACKGROUND

Postoperative atrial fibrillation (POAF) occurs in 20-40% patients who received isolated coronary artery cardiac bypass surgery (CABG). Several POAF risk prediction models have been developed, but none of them is widely adopted in practice. Our objective was to derive and validate a simple scoring system to estimate POAF risk after isolated CABG, using easily available clinical information.

METHODS

Medical records of 1,000 consecutive patients undergoing isolated CABG were reviewed. The data of first 700 patients were used for model derivation and data of the remaining 300 patients were used for model validation. Discrimination and calibration of the newly developed model were assessed.

RESULTS

POAF incidence in both the derivation and validation cohorts was 27.3%. Age ≥65, history of hypertension, heart failure, and myocardial infarction were independently associated with POAF risk. Risk scores were calculated by summing weighting points for each independent predictor. The score ≥3 was associated with high POAF incidence (41.1% in the derivation cohort and 44.3% in the validation cohort). The positive and negative POAF predictive value was 41.1% and 78.5%, respectively, in the derivation cohort, and 44.3% and 80.8%, respectively, in the validation cohort, when the cut-point score ≥3 was used. The Hosmer-Lemeshow goodness-of-fit test P-values were 0.917 and 0.894 in the derivation cohort and validation cohort, respectively.

CONCLUSIONS

This POAF risk following isolated CABG can be predicted with simple patient characteristic during the preoperative period. Patients with high risk scores (≥3) may constitute a target population for POAF prevention and prolonged postoperative surveillance.

A comparison of the CHARGE-AF and the CHA2DS2-VASc risk scores for prediction of atrial fibrillation in the Framingham Heart Study

BACKGROUND

Atrial fibrillation (AF) affects more than 33 million individuals worldwide and increases risks of stroke, heart failure, and death. The CHARGE-AF risk score was developed to predict incident AF in three American cohorts and it was validated in two European cohorts. The CHA2DS2-VASc risk score was derived to predict risk of stroke, peripheral embolism, and pulmonary embolism in individuals with AF, but it has been increasingly used for AF risk prediction. We compared CHARGE-AF risk score versus CHA2DS2-VASc risk score for incident AF risk in a community-based cohort.

METHODS AND RESULTS

We studied Framingham Heart Study participants aged 46 to 94 years without prevalent AF and with complete covariates. We predicted AF risk using Fine-Gray proportional sub-distribution hazards regression. We used the Wald χ(2) statistic for model fit, C-statistic for discrimination, and Hosmer-Lemeshow (HL) χ(2) statistic for calibration. We included 9722 observations (mean age 63.9 ± 10.6 years, 56% women) from 4548 unique individuals: 752 (16.5%) developed incident AF and 793 (17.4%) died. The mean CHARGE-AF score was 12.0 ± 1.2 and the sub-distribution hazard ratio (sHR) for AF per unit increment was 2.15 (95% CI, 99-131%; P < .0001). The mean CHA2DS2-VASc score was 2.0 ± 1.5 and the sHR for AF per unit increment was 1.43 (95% CI, 37%-51%; P < .0001). The CHARGE-AF model had better fit than CHA2DS2-VASc (Wald χ(2) = 403 vs 209, both with 1 df), improved discrimination (C-statistic = 0.75, 95% CI, 0.73-0.76 vs C-statistic = 0.71, 95% CI, 0.69-0.73), and better calibration (HL χ(2) = 5.6, P = .69 vs HL χ(2) = 28.5, P < .0001).

CONCLUSION

The CHARGE-AF risk score performed better than the CHA2DS2-VASc risk score at predicting AF in a community-based cohort.

Efficacy of atorvastatin in prevention of atrial fibrillation after heart valve surgery in the PROFACE trial (PROphylaxis of postoperative atrial Fibrillation After Cardiac surgEry)

Background

To evaluate the efficacy of perioperative atorvastatin administration for prophylaxis of postoperative atrial fibrillation (POAF) after heart valve surgery.

Methods

Our study included 90 patients with heart valve disease who were scheduled to undergo elective cardiac surgery. Cases with previous AF or preoperative beta-blocker therapy were excluded. Patients were randomized into the atorvastatin group, which included 47 patients who received 40 mg/day of atorvastatin 7 days before and after the surgery and the control group, which included 43 patients. Primary endpoint was the occurrence of POAF. Secondary endpoints included modifications in the preoperative and postoperative levels of the markers of inflammation (C-reactive protein [CRP]), myocardial injury (ultrasensitive troponin T and creatinine phosphokinase MB [CPK-MB]), and cardiac dysfunction (pro-brain natriuretic peptide [proBNP]) related to POAF and changes in the echocardiographic parameters, such as atrial electromechanical interval, A wave, E/A ratio, and Doppler imaging systolic velocity wave amplitude, related to POAF.

Results

No relationship between atorvastatin administration and reduction in the incidence of POAF was observed (42.6% in the atorvastatin vs. 30.2% in the control group) (p=0.226). No difference in the levels of CPK-MB, ultrasensitive troponin T, CRP, or proBNP and in the analyzed echocardiographic parameter was detected between both groups.

Conclusions

Atorvastatin in the described dose, was not adequate for the prophylaxis of POAF after heart valve surgery. It was ineffective in controlling the inflammatory phenomena, myocardial injury, and echocardiographic predictors of POAF.

De novo atrial fibrillation post cardiac surgery: the Durban experience

Atrial fibrillation (AF) is the most common complication post cardiac surgery and results in elevated morbidity and mortality rates and healthcare costs. A pilot, retrospective study of the medical records of all adult patients developing de novo AF post surgery was undertaken at the cardiac surgical unit in Durban between 2009 and 2012. We aimed to describe the local experience of AF with a view to suggesting an adapted local treatment policy in relation to previously published data. Fifty-nine patients developed AF during the study period. AF occurred predominantly three or more days post surgery. Thirty-five patients required cardioversion and amiodarone to restore sinus rhythm. Return to the general ward (RGW) was 4.6 days longer than the institutional norm. Liberal peri-operative β-blocker and statin use is currently preferred to a formal prophylaxis strategy. Randomised, controlled trials are required to evaluate measures curbing prolonged length of stay and morbidity burdens imposed by AF on the local resource-constrained environment.

Meta-analysis of CHADS2 Score in Predicting Atrial Fibrillation

The CHADS2 score is a validated clinical tool used for the risk stratification of stroke in the presence of atrial fibrillation (AF). Recently, some studies have shown that CHADS2 score may predict the risk of AF, which yielded conflicting results. The purpose of this study is to perform a meta-analysis of observational studies to examine the association between the CHADS2 score and risk of AF. Using PubMed and EMBASE database, we searched published articles by November 2014 to identify studies that evaluated the association between CHADS2 score and the risk of AF. We used both fixed-effects and random-effects models to calculate the overall effect estimate. A sensitivity analysis and subgroup analysis were performed to find the origin of heterogeneity. Of the 1,806 studies identified initially, 19 studies were included into our analysis, with a total of 714,672 patients. The CHADS2 score was found to be an independent predictor of AF as both a continuous variable (odds ratio 1.43, 95% confidence interval 1.10 to 1.86, p = 0.007) and categorical variable (odds ratio 3.37, 95% confidence interval 2.65 to 4.28, p <0.00001). Subgroup analysis revealed that different patients' age in study population may be a possible reason for the significant heterogeneity in our meta-analysis. In conclusion, CHADS2 score predicts the risk of AF. Addressing risk factors and early recognition of AF are important and also awareness of CHADS2 score to reduce stroke risk with pharmacologic prophylaxis.