Renal dysfunction and the risk of thromboembolic events in patients with atrial fibrillation after catheter ablation—The potential role beyond the CHA2DS2-VASc score

The risk factors of thrombus formation and the effect of catheter ablation on repetitive thrombus formation in patients with atrial fibrillation: a single center retrospective study in China

BACKGROUND

Atrial fibrillation (AF) predisposes patients to the formation of atrial thrombi. The CHA₂DS₂-VASc score does not include all risk factors for atrial thrombosis. The present study is designed to explore the influencing factors of thrombus formation in patients with AF and to investigate the effect of catheter ablation (CA) on recurrent thrombosis in patients with a history of intracardiac thrombus.

METHODS

(1) This study consisted of 1726 patients that underwent CA, among which 58 patients had a history of intracardiac thrombus prior to CA. The risk factors for thrombus formation were explored by comparing the baseline clinical characteristics of patients with and without atrial thrombus. (2) The left atrial appendage flow velocity (LAAFV) in patients with a history of intracardiac thrombus who were willing to undergo transesophageal echocardiography (TEE) at the latest follow-up were examined, and comparisons of the LAAFV was made before and after CA.

RESULTS

The median follow-up period is 13 months. Persistent AF was found to be the only independent risk factor affecting the formation of atrial thrombus among the investigated factors (OR 3.152; 95%CI 1.806-5.500; p < 0.001). Twenty-seven patients agreed to undergo TEE during follow-up, no clinical ischemic stroke events were recorded, no recurrent intracardiac thrombus formation was detected in patients, 15 patients maintained sinus rhythm (55.6%) during follow-up; successful CA significantly increased LAAFV (difference between latest evaluation prior to CA 17.46 ± 14.81 cm/s, p < 0.001).

CONCLUSIONS

Persistent AF is the only independent risk factor for thrombus formation. Successful CA may improve the LAAFV and thereby decrease the risk of intracardiac thrombus formation.

Comprehensive comparison of stroke risk score performance: a systematic review and meta-analysis among 6 267 728 patients with atrial fibrillation

AIMS

Multiple risk scores to predict ischaemic stroke (IS) in patients with atrial fibrillation (AF) have been developed. This study aims to systematically review these scores, their validations and updates, assess their methodological quality, and calculate pooled estimates of the predictive performance.

METHODS AND RESULTS

We searched PubMed and Web of Science for studies developing, validating, or updating risk scores for IS in AF patients. Methodological quality was assessed using the Prediction model Risk Of Bias ASsessment Tool (PROBAST). To assess discrimination, pooled c-statistics were calculated using random-effects meta-analysis. We identified 19 scores, which were validated and updated once or more in 70 and 40 studies, respectively, including 329 validations and 76 updates-nearly all on the CHA2DS2-VASc and CHADS2. Pooled c-statistics were calculated among 6 267 728 patients and 359 373 events of IS. For the CHA2DS2-VASc and CHADS2, pooled c-statistics were 0.644 [95% confidence interval (CI) 0.635-0.653] and 0.658 (0.644-0.672), respectively. Better discriminatory abilities were found in the newer risk scores, with the modified-CHADS2 demonstrating the best discrimination [c-statistic 0.715 (0.674-0.754)]. Updates were found for the CHA2DS2-VASc and CHADS2 only, showing improved discrimination. Calibration was reasonable but available for only 17 studies. The PROBAST indicated a risk of methodological bias in all studies.

CONCLUSION

Nineteen risk scores and 76 updates are available to predict IS in patients with AF. The guideline-endorsed CHA2DS2-VASc shows inferior discriminative abilities compared with newer scores. Additional external validations and data on calibration are required before considering the newer scores in clinical practice.

CLINICAL TRIAL REGISTRATION

ID CRD4202161247 (PROSPERO).

Left Atrial Septal Pouch-Is it Really a New Risk Factor for Ischemic Stroke?: Subanalysis of the ASSAM Study

PURPOSE

The atrial septal pouch is an anatomic variant of the interatrial septum caused by incomplete fusion of the septum primum and secundum. It is debatable whether coexistence of septal pouch and atrial fibrillation (AF) increases the risk of stroke. Thus, the aim of the study was to evaluate the coexistence of left atrial septal pouch (LASP) and AF in patients with a history of stroke in comparison with those without an earlier history of stroke.

MATERIALS AND METHODS

We analyzed 145 patients with AF (68 in the study group, 77 in the control group). The study group consisted of patients with previous stroke and AF; control group consisted of patients scheduled for AF ablation. All patients underwent computed tomography with the assessment of atrial septum morphology and presence of LASP. The study was a subanalysis of the ASSAM (AssesSment of the left atrial appendage morphoLogy in patients aAfter ischaeMic Stroke) study.

RESULTS

The prevalence of LASP in the entire group was 38.6%. There were no significant differences in the prevalence of LASP between the study and control groups (33.8% vs. 42.9%, P=0.265). Mean longitudinal and transverse dimensions of LASP were 9.34±3.27 and 2.4±0.6 mm, respectively, and there was no significant difference between the study and controls. Patients from the stroke group were older (P<0.0001), had a higher CHA2DS2-VASc score (5.41±1.93 vs. 1.62±1.46, P<0.0001) compared with controls.

CONCLUSIONS

Presence of LASP is not more prevalent in patients with a history of stroke. Additional information on the presence of LASP do not improve accuracy of risk stratification for stroke in patients with AF.

Renal function and outcomes in atrial fibrillation patients after catheter ablation

BACKGROUND

Atrial fibrillation (AF) and renal failure coexist and interact. However, scarce data about association between renal function and clinical outcomes in patients undergoing catheter ablation for AF are available. We sought to evaluate long-term renal function and clinical outcomes after AF ablation.

METHODS

We enrolled 791 non-dialysis patients undergoing catheter ablation for AF, and evaluated the incidence of worsening renal function (WRF) after the procedure, defined as >30% decline in estimate glomerular filtration rate.

RESULTS

Mean follow-up duration was 5.1±2.5 years. Five hundreds and twenty-six patients (66.5%) were free from recurrent atrial arrhythmias without any antiarrhythmic drugs at the time of final follow-up. Cumulative incidence of WRF was 13.2% at 5-year after procedure, which was significantly higher in patients with recurrent AF compared to those without (21.6% versus 8.7%, P<0.001). In the multivariable analysis, recurrent AF was an independent risk factor for WRF (adjusted hazard ratio [HR] 1.89, 95% confidence interval 1.27-2.81, P = 0.002), along with congestive heart failure, diabetes, and eGFR <60 ml/min/1.73m2 at baseline. Patients with WRF had significantly higher 5-year incidences of all-cause death, cardiovascular death, heart failure hospitalization, ischemic stroke, and major bleeding compared to those without WRF. After adjustment of baseline differences in the multivariate Cox model, the excessive risks of WRF for all-cause death and heart failure hospitalization remained significant (adjusted HR 3.46, P = 0.002; adjusted HR 3.67, P<0.001).

CONCLUSIONS

In AF patients undergoing catheter ablation for AF, arrhythmia recurrence was associated with WRF during follow-up, which was a strong predictor of adverse clinical outcomes.

Risk factors for left atrial appendage thrombus

Background: Atrial fibrillation (AF) is the most common persistent rhythm disorder that has been shown to be associated with a significant increase in stroke risk. Left atrial appendage (LAA) thrombi are responsible for most of strokes of cardiac origin. CHA₂DS₂-VASc is a risk scoring system to identify patients' indications for anticoagulation in nonvalvular AF patients. The aim of our study was to investigate CHA₂DS₂-VASc score, the other risk factors, echocardiographic data and blood parameters for LAA thrombus.Methods: Two hundred and sixty-four patients who were admitted to our adult cardiology outpatient clinic and who underwent a transesophageal echocardiography procedure between June 2017 and June 2019 included in our study. Patient's demographic data, transthoracic echocardiographic examinations, and laboratory results were recorded retrospectively.Results: LAA thrombus was detected in 39 (14.7%) patients. The rates of coronary artery disease and systolic dysfunction were significantly higher in patients with LAA thrombus (p = .017, p = .016, respectively). When AF subtypes were examined in detail, thrombus rate was significantly higher in persistent AF (51 vs. 25.7%, p = .002). Although the CHA₂DS₂-VASc score was slightly higher in the thrombus group, there was no statistically significant difference between the two groups (3.0 ± 1.65 vs. 2.78 ± 1.66).Conclusions: In conclusion, CHA₂DS₂-VASc score system itself was not informative about LAA thrombus formation although some of its components were related with LAA thrombus formation. According to a multiple regression analysis, the independent determinants of LAA thrombus were the presence of AF and coronary artery disease.

Systematic DOACs oral anticoagulation in patients with atrial fibrillation and chronic kidney disease: the nephrologist's perspective

Atrial fibrillation (AF) is highly prevalent among patients with chronic kidney disease (CKD), and also associated with unfavorable outcome. Anticoagulant therapy is the mainstep of management in such patients, aimed at reducing the high risk of systemic thromboembolism and especially of ischemic stroke, which is reportedly associated with increased mortality in CKD patients. Even though new direct oral anticoagulant agents (DOACs) proved to be effective in patients with non valvular chronic AF, and are therefore recommended by recent guidelines for their treatment, warfarin is currently used in more than one-half of subjects needing oral anticoagulation, and only 30% of them are converted from a vitamin K antagonist- to a DOAC-based regimen. The main reason for not prescribing DOACs is often a reduction in renal function, even if mild. Aim of this review was therefore to evaluate the impact of DOAC therapy in the setting of CKD, from a nephrological perspective, by comparing available evidence on the role of DOACs in patients with CKD and AF with that emerging from traditional warfarin-based therapy. Both the pathogenesis of AF in CKD, and available findings of renal, cardiovascular and bone effects of DOACs in CKD are discussed, leading to the conclusion that DOAC therapy should be considered as the first line therapy for non valvular AF in patients with mild and moderate reduction of renal function, and could also be adopted for patients with severe CKD not on hemodialysis treatment, whereas there is insufficient evidence for ESRD patients on dialysis.

Factors Associated with a Large Decline in Renal Function or Progression to Renal Insufficiency in Hospitalized Atrial Fibrillation Patients with Early-Stage CKD

Clinicians must consider renal function when administering anticoagulants for atrial fibrillation (AF). Determination of risk factors for renal function decline may enable identification of patients who require closer monitoring. We investigated the characteristics associated with renal function decline in patients with AF. The study cohort consisted of 631 AF patients who had at least one readmission during the follow-up period and stages 1-3 chronic kidney disease (CKD). The primary outcome measure was large renal function decline (≥30% decrease from baseline estimated glomerular filtration rate [eGFR]). The secondary outcome measure was a final eGFR < 60 mL/minute/1.73 m² for those with a baseline eGFR above this level. The mean eGFR was 74.4 ± 18.5 mL/minute/1.73 m², and the mean follow-up time was 30.2 ± 13.2 months. The primary outcome occurred in 155 patients (24.6%) and was associated with congestive heart failure (CHF), proteinuria, type of AF, and left atrial diameter (LAD) ≥ 45 mm. Among 478 patients with a baseline eGFR ≥ 60 mL/minute/1.73 m², 137 (28.7%) progressed to renal failure (eGFR < 60 mL/minute/1.73 m²). A decreasing eGFR was associated with age ≥ 75 years, CHF, lower baseline eGFR, and LAD ≥ 45 mm. CHF, proteinuria, type of AF, and LAD ≥ 45 mm were associated with eGFR decline ≥ 30% in AF patients with CKD stages 1-3. Advanced age, CHF, lower baseline eGFR, and LAD ≥ 45 mm were associated with progression to renal insufficiency. These results should be considered when identifying patients who require more frequent monitoring of eGFR.

Usefulness of transesophageal echocardiography before cardioversion in atrial arrhythmias

BACKGROUND

Although many thromboembolism risk factors are well defined, formation of thrombus or dense spontaneous contrast (sludge) in the left atrium remains enigmatic and confounding. Exclusion of the thrombus is extremely important with respect to planned reversal of sinus rhythm. Data regarding the routine transesophagal echocardiography (TEE) before cardioversion are inconclusive. The authors focused on analyzing the usefulness of TEE before cardioversion by assessment of factors influencing the risk of thrombus and/or dense spontaneous echo contrast with the intention of extending indications for TEE in the group with a high risk of thrombus or to forgo TEE in the low risk group.

METHODS

Two hundred sixty-nine consecutive patients with persistent (> 48 h) atrial fibrillation or atrial flutter, in whom a direct current cardioversion was planned, were undergoing TEE for the detection of the left atrial thrombus or dense spontaneous echo contrast. Additional clinical and echocardiographic data were collected. The relationship between both thrombus and dense spontaneous echo contrast and covariates was analyzed with the use of binary logistic regression.

RESULTS

Left atrium (LA) appendage (LAA) thrombus and/or sludge were detected in 79 (29%) patients. Signs of dementia in mini-mental state examination (hazard ratio [HR]: 1.16; p = 0.005), low velocities in LAA (HR: 3.38; p = 0.032); presence of spontaneous echo contrast in LA (HR: 3.38; p = 0,003) consecutive episode of AF (HR: 2.27; p = 0,046); longer duration of atrial fibrillation (HR: 1.009; p = 0.022); were significant predictors of thrombus and/or dense spontaneous echo contrast. None of the patients with a CHA2DS2VASc score ≤ 1 had thrombus or sludge in the LAA. Among patients with a CHA2DS2VASc score > 1, the prevalence of thrombus or sludge in LAA was independent of the CHA2DS2VASc score value.

CONCLUSIONS

Amongst many factors, including an established as risk for thromboembolism only a few of them increased the risk for the presence of thrombus in LAA: low velocities in LAA, presence of spontaneous echo contrast, longer duration of arrhythmia, consecutive (not first) arrhythmia episode and signs of dementia from a mini-mental state examination questionnaire. It was believed that there could be a need for an extension of indications of TEE in vast majority of the patients with atrial arrhythmias, due most often to an unpredictable occurrence of thrombus and potentially disastrous thromboembolism. The only exception could have been the group of the patients with a CHA2DS2VASc score ≤ 1.

Atrial fibrillation type and renal dysfunction as important predictors of left atrial thrombus

OBJECTIVE

We aimed to identify predictors of left atrial appendage (LAA) thrombus in patients with atrial fibrillation (AF) and to enhance the prognostic value of the CHA₂DS₂-VASc score.

METHODS

Derivation cohort included 1033 consecutive AF patients referred for catheter ablation or direct current cardioversion, in whom transoesophageal echocardiography (TOE) was performed prior to the procedure. Logistic regression analysis was used to identify predictors of LAA thrombus on TOE. Receiver operating characteristic (ROC) curves were constructed to compare the newly developed score with the CHA₂DS₂ and CHA₂DS₂-VASc scores in the derivation and the validation (n=320) cohort.

RESULTS

On TOE, LAA thrombus was present in 59 (5.7%) patients in the derivation cohort. Aside from variables encompassed by the CHA₂DS₂-VASc score, LAA thrombus predictors included AF type (persistent/'permanent' vs paroxysmal) and renal dysfunction. These predictors were incorporated into the CHA₂DS₂-VASc score. In ROC analysis, area under the curve (AUC) for the new score (CHA₂DS₂-VASc-RAF score) was significantly higher (0.81) than those for the CHA₂DS₂ and CHA₂DS₂-VASc scores (0.71 and 0.70, respectively). In the validation cohort, the CHA₂DS₂-VASc-RAF score also performed significantly better (AUC of 0.88) than the CHA₂DS₂ and CHA₂DS₂-VASc scores (AUC of 0.63 and 0.60, respectively).

CONCLUSION

In real-world AF patients with majority on oral anticoagulation, LAA thrombus was found in approximately 6%. Two variables not included in the CHA₂DS₂-VASc score (AF type and renal dysfunction) proved strong, independent predictors of LAA thrombus and might improve thromboembolic risk stratification.

Decreased Renal Function Is Associated with Elevated CHA2DS2VASC and R2CHADS2 Scores in Non-Valvular Atrial Fibrillation Patients Presenting with Stroke

Introduction

Atrial fibrillation (AF), the most common cardiac arrhythmia, affects approximately 2.3 million patients in the United States, costing around $26 billion. Atrial fibrillation is associated with a two- to seven-fold increased risk of stroke, one of the most serious complications. Chronic kidney disease affects approximately 13% of the US population and has been associated with higher rates of AF than the general population. In patients with chronic kidney disease (CKD), the risk of stroke increases as the glomerular filtration rate (GFR) decreases, especially in CKD stages three and four.

Several risks stratification scores such as CHADS2 (congestive heart failure, hypertension, age, diabetes mellitus, stroke), CHA2DS2VASc (congestive heart failure, hypertension, age, diabetes mellitus, stroke, vascular disease, age, sex), and R2CHADS2 (renal failure, congestive heart failure, age, diabetes, stroke) scores are used for stroke risk assessment in patients with non-valvular atrial fibrillation (NVAF). This study investigates the association between renal functions and risk stratification scoring systems in patients with non-valvular AF presenting with stroke.

Methods

Using the convenience sampling method, 171 subjects were selected from the eligible population (n = 386). A Pearson product-moment correlation coefficient was calculated to determine the association between the GFR and each of the CHA2DS2VASc and R2CHADS2 scores. In addition, a Pearson product-moment correlation coefficient was calculated to determine the association between the CHA2DS2VASc and R2CHADS2 scores.

Results

The selected population represented 44.3% of the eligible subjects. Of these, 88% were Caucasian, 60% were female, and the mean age was 78 years. The mean CHA2DS2VASc score was six (range 2-9). The mean eGFR was 69.77 (range 6-108). Both the mode and the median CHA2DS2VASc score was four (range 2-8). A weak, but significant, negative correlation was found between renal function (eGFR) and the CHA2DS2VASc score (r = -0.263; p = 0.0005). There was a stronger negative correlation between the eGFR and R2CHADS2score (r = -0.70; p < 0.00001). The CHA2DS2VASc and R2CHADS2scoring schemes were significantly and positively correlated (r = 0.627; p < 0.00001).

Discussion

In NVAF patients presenting with stroke, renal failure is associated with higher CHA2DS2VASc and R2CHADS2 scores. One must consider renal failure (end-stage or non-end stage renal failure) as an additional potential risk factor for stroke when recommending anticoagulation in non-valvular atrial fibrillation. 

Predicting in a predicament: Stroke and hemorrhage risk prediction in dialysis patients with atrial fibrillation

Whether to anticoagulate dialysis patients with atrial fibrillation is a common clinical dilemma with limited high-quality data to inform decision-making. While the efficacy and safety of anticoagulation for stroke prevention in dialysis patients with atrial fibrillation has long been debated and remains unclear, the more upstream issue of stroke risk assessment from atrial fibrillation has received relatively little attention. In the general population, a handful of risk scores to help predict stroke and hemorrhage risk in the setting of atrial fibrillation are widely validated and applied in clinical practice. But are they applicable to the dialysis population? The most commonly used stroke risk scores, CHADS2 and CHA2DS2-VASC, have limited validation in the dialysis population, and when validated, have shown poor performance (c-statistics <0.70). Stroke risk scores derived in the general atrial fibrillation population may perform poorly in dialysis patients for a number of reasons. Dialysis patients have unique stroke risk factors, such as chronic inflammation and vascular calcification, and a much higher competing risk of death, none of which are accounted for in current risk scores. Further complicating the dilemma of anticoagulation is hemorrhage risk, which is known to be exceedingly high in dialysis patients. Currently available hemorrhage risk scores, such as HAS-BLED, have not been validated in dialysis patients and will likely underestimate hemorrhage risk. Moving forward, risk tools specific to the dialysis population are needed to accurately assess and balance stroke and hemorrhage risks in dialysis patients with atrial fibrillation.

Addition of B-Type Natriuretic Peptide to Existing Clinical Risk Scores Enhances Identification of Patients at Risk for Atrial Fibrillation Recurrence After Pulmonary Vein Isolation

INTRODUCTION

Predicting which patients will be free from atrial fibrillation (AF) after pulmonary vein isolation (PVI) remains challenging. Clinical risk prediction scores show modest ability to identify patients at risk for AF recurrence after PVI. B-type natriuretic peptide (BNP) is associated with risk for incident and recurrent AF but is not currently included in existing AF risk scores. We sought to evaluate the incremental benefit of adding preoperative BNP to existing risk scores for predicting AF recurrence during the 6 months after PVI.

METHODS

One hundred sixty-one patients with paroxysmal or persistent AF underwent an index PVI procedure between 2010 and 2013; 77 patients (48%) had late AF recurrence after PVI (>3 months post-PVI) over the 6-month follow-up period.

RESULTS

A BNP greater than or equal to 100 pg/dL (P=0.01) and AF recurrence within 3 months after PVI (P<0.001) were associated with late AF recurrence in multivariate analyses. Addition of BNP to existing clinical risk scores significantly improved the areas under the curve for each score, with an integrated discrimination improvement of 0.08 (P=0.001) and a net reclassification improvement of 60% (P=0.001) for all risk scores.

CONCLUSIONS

Circulating BNP levels are independently associated with late AF recurrence after PVI. Inclusion of BNP significantly improves the discriminative ability of CHADS2, CHA2DS2-VASc, R2CHADS2, and the HATCH score in predicting clinically significant, late AF recurrence after PVI and should be incorporated in decision-making algorithms for management of AF. B-R2CHADS2 is the best score model for prediction of late AF recurrence.

Increased risk of atrial fibrillation in end-stage renal disease patients on dialysis: A nationwide, population-based study in Taiwan

End-stage renal disease (ESRD) patients commonly have a higher risk of developing cardiovascular diseases than general population. Chronic kidney disease is an independent risk factor for atrial fibrillation (AF); however, little is known about the AF risk among ESRD patients with various modalities of renal replacement therapy. We used the Taiwan National Health Insurance Research Database to determine the incident AF among peritoneal dialysis (PD) and hemodialysis (HD) patients in Taiwan.Our ESRD cohort include Taiwan National Health Insurance Research Database, we identified 15,947 patients, who started renal replacement therapy between January 1, 2002 and December 31, 2003. From the same data source, 47,841 controls without ESRD (3 subjects for each patient) were identified randomly and frequency matched by gender, age (±1 year), and the year of the study patient's index date for ESRD between January 1, 2002 and December 31, 2003.During the follow-up period (mean duration: 8-10 years), 3428 individuals developed the new-onset AF. The incidence rate ratios for AF were 2.07 (95% confidence interval [CI] = 1.93-2.23) and 1.78 (95% CI = 1.30-2.44) in HD and PD groups, respectively. After we adjusted for age, gender, and comorbidities, the hazard ratios for the AF risk were 1.46 (95% CI = 1.32-1.61) and 1.32 (95% CI = 1.00-1.83) in HD and PD groups, respectively. ESRD patients with a history of certain comorbidities including hypertension, diabetes mellitus, hyperlipidemia, coronary artery disease, heart failure, valvular heart disease, and chronic obstructive pulmonary disease (COPD) have significantly increased risks of AF.This nationwide, population-based study suggests that incidence of AF is increased among dialysis ESRD patients. Furthermore, we have to pay more attention in clinical practice and long-term care for those ESRD patients with a history of certain comorbidities.

Stroke Risk Factors Beyond the CHA₂DS₂-VASc Score: Can We Improve Our Identification of "High Stroke Risk" Patients With Atrial Fibrillation?

The prevention of stroke and other thromboembolic events plays a crucial role in the management of patients with atrial fibrillation. Not all patients with atrial fibrillation are equal in terms of thromboembolic risk; therefore, not all will benefit from oral anticoagulation treatment. The general principle is that the expected benefit of anticoagulation in reduction of thromboembolic risk must exceed the expected harm caused by possible bleeding. Some guidelines have focused on a categorical approach to stroke prevention, with a focus on identifying patients at high risk for oral anticoagulation. Various current guidelines recommend assessment of stroke risk using the CHADS2 or CHA2DS2-VASc scores to initially detect patients at low risk who require no antithrombotic therapy. However, the scores do not incorporate all possible risk factors causing a high thromboembolic risk. Factors such as impaired renal function, obstructive sleep apnea, and echocardiographic and biochemical or coagulation parameters can also predict adverse thromboembolic events. The present review aims to describe biomarkers whether blood, urine, imaging (cardiac or cerebral), or clinical that go beyond the CHA2DS2-VASc score and potentially aid stroke risk assessment. Although useful in some cases, the presented parameters should be perhaps used to further refine initial identification of patients at low risk, after which effective stroke prevention can be offered to those with ≥1 additional stroke risk factors.

Risk of Ischemic Stroke and Stroke Prevention in Patients with Atrial Fibrillation and Renal Dysfunction

Chronic kidney disease (CKD) has been identified as an important risk factor for new-onset atrial fibrillation (AF) and would significantly increase the risk of AF-related strokes. Stroke prevention in AF patients with CKD is a big challenge, especially for patients with end-stage renal disease (ESRD) undergoing long-term dialysis. In addition to an increase risk of stroke, renal dysfunction was also associated with a higher risk of hemorrhage due to dysregulation of coagulation and uremia-mediated platelet dysfunction. Therefore, the net clinical benefit balancing stroke risk reduction and increased risk of bleeding should be weighed carefully before initiating oral anti-coagulants for ESRD patients. Several studies investigating whether warfarin should be used for stroke prevention in AF patients with ESRD have been published and showed inconsistent results. Since none of these studies was a prospective and randomized trial, the best strategy for stroke prevention in AF patients with ESRD undergoing dialysis remained unknown and more data are necessary to answer this issue.

Incidence and risk factors for new-onset atrial fibrillation among patients with end-stage renal disease undergoing renal replacement therapy

Atrial fibrillation (AF) is prevalent in end-stage renal disease (ESRD) patients and negatively impacts patient outcomes. We explored the incidence and risk factors for new-onset AF among patients with ESRD undergoing renal replacement therapy, without a prior history of AF, retrieved from Taiwan's National Health Insurance Research Database (NHIRD). For each of 134,901 patients with ESRD, one age- and gender-matched control and one similarly matched patient with chronic kidney disease (CKD), a total of 404,703 patients, were selected from the NHIRD. The study endpoint was the occurrence of new-onset AF and patients were followed an average of 5.1 years. The incidence rates of AF were 12.1, 7.3, and 5.0 per 1000 person-years for ESRD, CKD, and control patients, respectively. Among patients with ESRD, age, hypertension, heart failure, coronary artery disease, peripheral arterial occlusive disease, and chronic obstructive pulmonary disease were significant risk factors for new-onset AF. Thus, patients with ESRD had a significantly higher risk of new-onset AF. The presence of multiple risk factors was associated with a higher possibility of AF occurrence.

Oral anticoagulation therapy after radiofrequency ablation of atrial fibrillation and the risk of thromboembolism and serious bleeding: long-term follow-up in nationwide cohort of Denmark

AIM

To investigate the long-term risk of thromboembolism and serious bleeding associated with oral anticoagulation (OAC) therapy beyond 3 months after radiofrequency ablation (RFA) of atrial fibrillation (AF).

METHODS AND RESULTS

Linking Danish administrative registries, 4050 patients undergoing first-time RFA (2000-11) were identified. Risk of thromboembolism and serious bleeding according to OAC therapy were analysed by incidence rates (presented per 100 person-years) and Cox proportional-hazard models. The median age was 59.5 years (interquartile range, IQR: 52.8-65.2); 26.5% were females. During a median follow-up of 3.4 years (IQR: 2.0-5.6), 71 (1.8%) thromboembolism cases were identified, where incidence rates with and without OAC were 0.56 (0.40-0.78)95%CI and 0.64 (0.46-0.89)95%CI, respectively. Oral anticoagulation discontinuation remained insignificant [hazard ratio 1.42(0.86-2.35)95%CI] in multivariable analysis. Beyond 3 months after RFA 87 (2.1%) serious bleedings occurred; incidence rates with and without OAC were 0.99 (0.77-1.27)95%CI and 0.44 (0.29-0.65)95%CI, respectively. Oral anticoagulation therapy was significantly associated with serious bleeding risk [hazard ratio 2.05(1.25-3.35)95%CI]. In an age- and gender-matched cohort (1 : 4) of 15 848 non-ablated AF patients receiving rhythm-control therapy, thromboembolic rates with and without OAC were 1.34 (1.21-1.49)95%CI and 2.14 (1.98-2.30)95%CI, respectively. Adjusted incidence rate ratio was 0.53 (0.43-0.65)95%CI favouring RFA cohort.

CONCLUSION

Thromboembolic risk beyond 3 months after RFA was relatively low compared with a matched non-ablated AF cohort. With cautious interpretation due to low number of events, serious bleeding risk associated with OAC seems to outweigh the benefits of thromboembolic risk reduction. Randomized studies are warranted to test our results.

NKX2-6 mutation predisposes to familial atrial fibrillation

Atrial fibrillation (AF) is the most common form of sustained cardiac arrhythmia and is associated with substantially increased morbidity and mortality rates. Aggregating evidence demonstrates that genetic defects are involved in the pathogenesis of AF and a number of AF-associated genes have been identified. Nevertheless, AF is a genetically heterogeneous disorder and the genetic components underpinning AF in an overwhelming majority of patients remain unclear. In this study, the entire coding exons and splice junction sites of the NK2 homeobox 6 (NKX2-6) gene, which encodes a homeodomain transcription factor important for cardiovascular development, were sequenced in 150 unrelated patients with lone AF, and a novel heterozygous NKX2-6 mutation, p.Q175H, was identified in an index patient. Genetic analysis of the available family members of the mutation carrier revealed that the mutation co-segregated with AF transmitted in an autosomal dominant pattern. The missense mutation was absent in the 200 unrelated ethnically matched healthy individuals used as controls and the altered amino acid was completely conserved evolutionarily among species. Due to unknown transcriptional targets of NKX2-6, the functional characteristics of the mutation as regards transcriptional activity were analyzed using NKX2-5 as a surrogate. Alignment between human NKX2-6 and NKX2-5 proteins displayed that the Q175H-mutant NKX2-6 was equivalent to the Q181H-mutant NKX2-5, and the introduction of Q181H into NKX2-5 significantly decreased its transcriptional activity at the atrial natriuretic factor promoter. The present study firstly associates genetically defective NKX2-6 with enhanced susceptibility to AF, providing novel insight into the molecular mechanisms underlying AF and suggesting potential strategies for the antenatal prophylaxis and personalized treatment of AF.

2014 focused update of the Canadian Cardiovascular Society Guidelines for the management of atrial fibrillation

Atrial fibrillation (AF) is an extremely common clinical problem with an important population morbidity and mortality burden. The management of AF is complex and fraught with many uncertain and contentious issues, which are being addressed by extensive ongoing basic and clinical research. The Canadian Cardiovascular Society AF Guidelines Committee produced an extensive set of evidence-based AF management guidelines in 2010 and updated them in the areas of anticoagulation and rate/rhythm control in 2012. In late 2013, the committee judged that sufficient new information regarding AF management had become available since 2012 to warrant an update to the Canadian Cardiovascular Society AF Guidelines. After extensive evaluation of the new evidence, the committee has updated the guidelines for: (1) stroke prevention principles; (2) anticoagulation of AF patients with chronic kidney disease; (3) detection of AF in patients with stroke; (4) investigation and management of subclinical AF; (5) left atrial appendage closure in stroke prevention; (6) emergency department management of AF; (7) periprocedural anticoagulation management; and (8) rate and rhythm control including catheter ablation. This report presents the details of the updated recommendations, along with their background and rationale. In addition, a complete set of presently applicable recommendations, those that have been updated and those that remain in force from previous guideline versions, is provided in the Supplementary Material.

Incidence and prediction of ischemic stroke among atrial fibrillation patients with end-stage renal disease requiring dialysis

BACKGROUND

Renal dysfunction is a significant risk factor for ischemic stroke in atrial fibrillation (AF). However, the incidence of ischemic stroke and how to predict its occurrence among AF patients with end-stage renal disease (ESRD) are unclear.

OBJECTIVE

The purpose of this study was to compare the CHADS2 and CHA2DS2-VASc scores for stroke risk stratification in AF patients with ESRD.

METHODS

A total of 10,999 AF patients with ESRD undergoing renal replacement therapy who were not receiving oral anticoagulants or antiplatelet agents were identified from Taiwan's National Health Insurance Research Database. The study end-point was occurrence of ischemic stroke.

RESULTS

The median (interquartile) CHADS2 and CHA2DS2-VASc scores for the study cohort were 3 (2-5) and 5 (4-7), respectively. During follow-up, 1217 patients (11.7%) experienced ischemic stroke, with an incidence rate of 6.9 per 100 person-years. In Cox regression models, the CHADS2 and CHA2DS2-VASc scores both were significant predictors of ischemic stroke. C-indexes for CHADS2 and CHA2DS2-VASc were 0.608 and 0.682, respectively (P < .001). CHA2DS2-VASc improved the net reclassification index by 4.8% compared with CHADS2 (P < .0001). Among 1409 patients with a CHADS2 score of 0 or 1, the CHA2DS2-VASc score ranged from 1 to 4, with event rates ranging from 2.1 to 4.7 per 100 person-years.

CONCLUSION

The CHA2DS2-VASc score was useful in predicting ischemic stroke in AF patients with ESRD undergoing dialysis and was superior to the CHADS2 score. The net clinical benefit balancing stroke reduction against major bleeding with anticoagulation in these high-risk patients remains to be defined.

Comparison of CHADS2, R2CHADS2, and CHA2DS2-VASc scores for the prediction of rhythm outcomes after catheter ablation of atrial fibrillation: the Leipzig Heart Center AF Ablation Registry

BACKGROUND

Recurrences of atrial fibrillation (AF) occur in up to 30% within 1 year after catheter ablation. This study evaluated the value of CHADS2, R2CHADS2, and CHA2DS2-VASc scores for the prediction of rhythm outcomes after AF catheter ablation.

METHODS AND RESULTS

Using the Leipzig Heart Center AF Ablation Registry, we documented rhythm outcomes within the first 12 months in 2069 patients (67% men; 60±10 years; 35% persistent AF) undergoing AF catheter ablation. AF recurrences were defined as any atrial arrhythmia occurring within the first week (early recurrences, ERAF) and between 3 and 12 months (late recurrences, LRAF) after ablation. ERAF and LRAF occurred in 36% and 33%, respectively. On multivariable analysis, R2CHADS2 (odds ratio [OR], 1.11; 95% confidence interval [CI], 1.02-1.21; P=0.016) and CHA2DS2-VASc (OR, 1.09; 95% CI, 1.017-1.17; P=0.015) scores as well as persistent AF and left atrial diameter were significant predictors for ERAF. Similarly, the same clinical variables remained significant predictors for LRAF even after adjustment for ERAF, which was the strongest predictor for LRAF (HR, 3.12; 95% CI, 2.62-3.71; P<0.001). However, using receiver operating characteristic curve analyses, both scores demonstrated relatively low predictive value for ERAF (area under the curve [AUC], 0.536 [0.510-0.563]; P=0.007; and AUC, 0.547 [0.521-0.573]; P<0.001 for R2CHADS2 and CHA2DS2-VASc, respectively) and LRAF (AUC, 0.548 [0.518-0.578]; P=0.002; and AUC, 0.550 [0.520-0.580]; P=0.001).

CONCLUSIONS

R2CHADS2 and CHA2DS2-VASc were associated with rhythm outcomes after catheter ablation. However, AF type, left atrial diameter, and especially ERAF are also significant predictors for LRAF that should be included into new clinical scores for the prediction of rhythm outcomes after catheter ablation.

Stroke in Atrial Fibrillation - Long-term Follow-up of Cardiovascular Events

The incidence of atrial fibrillation (AF) was around 1.5 per 1000 person-years in Taiwan. Systemic thromboembolism is the most severe complication of AF. Risk stratification and adequate thromboembolism prophylaxis is the cornerstone of treatment in AF patients. The CHA2DS2-VASc score is powerful in selecting "truly low-risk" patients who are not necessary to receive anticoagulation therapies. It is also useful in predicting thromboembolic events and mortality for patients undergoing AF ablation. Recently, more and more biomarkers and imaging parameters were reported to be associated with adverse events in AF patients. How could these biomarkers and imaging tools change the current strategy of stroke prevention in AF deserves further investigations.

Renal Dysfunction, Stroke Risk Scores (CHADS 2 , CHA 2 DS 2 -VASc, and R 2 CHADS 2 ), and the Risk of Thromboembolic Events After Catheter Ablation of Atrial Fibrillation

Background—

There are limited data on the predictive value of stroke risk scores for thromboembolic events (TEs) after catheter ablation of atrial fibrillation (AF). Our objectives were to report the incidence of TEs after AF ablation in a large contemporary AF ablation cohort and to investigate the impact of renal dysfunction and the value of stroke risk stratification scores (CHADS 2 , CHA 2 DS 2 -VASc, and R 2 CHADS 2 ) for predicting TE after AF ablation.

Methods and Results—

Using the Leipzig Heart Center AF Ablation Registry, we documented TEs in patients undergoing radiofrequency AF catheter ablation. TE was defined as stroke, transient ischemic attack, or systemic embolism. Study population (N=2069; 66% men; 60±10 years; 62% paroxysmal AF; mean CHADS 2 , 1.2±0.9; CHA 2 DS 2 -VASc, 2.1±1.4; and R 2 CHADS 2 , 1.3±1.1) were followed up for a median 18 (Q1–Q3, 12–29) months (ie, 3078 patient-years). Overall, 31 TEs occurred, with 16 events within 30 days of ablation and 15 TEs (0.72%) during the follow-up period. On multivariate analysis, CHADS 2 ( P <0.001), R 2 CHADS 2 ( P <0.001), and CHA 2 DS 2 -VASc ( P =0.003) scores were independent predictors of TEs during follow-up, and AF recurrence conferred a nonsignificant trend for increased TE risk ( P =0.071–0.094). The CHA 2 DS 2 -VASc score further differentiated TE risk in patients with CHADS 2 and R 2 CHADS 2 0 to 1 (0.13% if CHA 2 DS 2 -VASc was 0–1 and 0.71% if CHA 2 DS 2 -VASc was >2) and had the best predictive value in patients with AF recurrences (c-index 0.894, P =0.022 versus CHADS 2 , P =0.031 versus R 2 CHADS 2 ).

Conclusions—

CHADS 2 , CHA 2 DS 2 -VASc, and R 2 CHADS 2 scores were associated with TE risk. The CHA 2 DS 2 -VASc score differentiated TE risk in the low-risk strata based on CHADS 2 and R 2 CHADS 2 scores and may be superior in the subgroup with AF recurrences.

Renal impairment and ischemic stroke risk assessment in patients with atrial fibrillation: the Loire Valley Atrial Fibrillation Project

OBJECTIVES

This study sought to determine the risk of ischemic stroke (IS)/thromboembolism (TE) associated with renal impairment and its incremental predictive value over established risk stratification scores (congestive heart failure, hypertension, age ≥75 years, diabetes, previous stroke [CHADS2] and congestive heart failure, hypertension, age ≥75 years, diabetes, previous stroke, vascular disease, age 65 to 74 years, sex category (female) [CHA₂DS₂-VASc]) in patients with atrial fibrillation (AF).

BACKGROUND

Risk stratification schemes for prediction of IS/TE in patients with AF are validated but do not include renal impairment.

METHODS

Patients diagnosed with nonvalvular AF and available estimated glomerular filtration rate (eGFR) data in a 4-hospital institution between 2000 and 2010 were identified. The study population was stratified by renal impairment defined by serum creatinine level and by eGFR measured at time of diagnosis of AF. Independent risk factors of IS/TE (including renal impairment) were investigated in Cox regression models. The incremental predictive value of renal impairment over CHADS₂ and CHA₂DS₂-VASc were assessed with the c-statistic, net reclassification improvement, and integrated discrimination improvement. We focused on the 1-year outcomes in our analyses.

RESULTS

Of 8,962 eligible individuals, 5,912 (66%) had nonvalvular AF and available eGFR data. Renal impairment by both creatinine and eGFR definitions was associated with higher rates of IS/TE at 1 year, compared with normal renal function. After adjustment for CHADS₂ risk factors, renal impairment did not significantly increase the risk of IS/TE at 1 year (hazard ratio: 1.06; 95% confidence interval [CI]: 0.75 to 1.49 for renal impairment; and hazard ratio: 1.09; 95% CI: 0.84 to 1.41 for eGFR). When renal impairment was added to existing risk scoring systems for stroke/TE (CHADS₂ and CHA₂DS₂-VASc), it did not independently add to the predictive value of the scores, whether defined by serum creatinine level or eGFR. This was evident even when the analysis was confined to only those patients with at least 1 year of follow-up.

CONCLUSIONS

Renal impairment was not an independent predictor of IS/TE in patients with AF and did not significantly improve the predictive ability of the CHADS₂ or CHA₂DS₂-VASc scores.