Abstract/Text: CONTEXT: Patients who have atrial fibrillation (AF) have an increased risk of stroke, but their absolute rate of stroke depends on age and comorbid conditions.
OBJECTIVE: To assess the predictive value of classification schemes that estimate stroke risk in patients with AF.
DESIGN, SETTING, AND PATIENTS: Two existing classification schemes were combined into a new stroke-risk scheme, the CHADS( 2) index, and all 3 classification schemes were validated. The CHADS( 2) was formed by assigning 1 point each for the presence of congestive heart failure, hypertension, age 75 years or older, and diabetes mellitus and by assigning 2 points for history of stroke or transient ischemic attack. Data from peer review organizations representing 7 states were used to assemble a National Registry of AF (NRAF) consisting of 1733 Medicare beneficiaries aged 65 to 95 years who had nonrheumatic AF and were not prescribed warfarin at hospital discharge.
MAIN OUTCOME MEASURE: Hospitalization for ischemic stroke, determined by Medicare claims data.
RESULTS: During 2121 patient-years of follow-up, 94 patients were readmitted to the hospital for ischemic stroke (stroke rate, 4.4 per 100 patient-years). As indicated by a c statistic greater than 0.5, the 2 existing classification schemes predicted stroke better than chance: c of 0.68 (95% confidence interval [CI], 0.65-0.71) for the scheme developed by the Atrial Fibrillation Investigators (AFI) and c of 0.74 (95% CI, 0.71-0.76) for the Stroke Prevention in Atrial Fibrillation (SPAF) III scheme. However, with a c statistic of 0.82 (95% CI, 0.80-0.84), the CHADS( 2) index was the most accurate predictor of stroke. The stroke rate per 100 patient-years without antithrombotic therapy increased by a factor of 1.5 (95% CI, 1.3-1.7) for each 1-point increase in the CHADS( 2) score: 1.9 (95% CI, 1.2-3.0) for a score of 0; 2.8 (95% CI, 2.0-3.8) for 1; 4.0 (95% CI, 3.1-5.1) for 2; 5.9 (95% CI, 4.6-7.3) for 3; 8.5 (95% CI, 6.3-11.1) for 4; 12.5 (95% CI, 8.2-17.5) for 5; and 18.2 (95% CI, 10.5-27.4) for 6.
CONCLUSION: The 2 existing classification schemes and especially a new stroke risk index, CHADS( 2), can quantify risk of stroke for patients who have AF and may aid in selection of antithrombotic therapy.

Abstract/Text: CONTEXT: Patients who have atrial fibrillation (AF) have an increased risk of stroke, but their absolute rate of stroke depends on age and comorbid conditions.
OBJECTIVE: To assess the predictive value of classification schemes that estimate stroke risk in patients with AF.
DESIGN, SETTING, AND PATIENTS: Two existing classification schemes were combined into a new stroke-risk scheme, the CHADS( 2) index, and all 3 classification schemes were validated. The CHADS( 2) was formed by assigning 1 point each for the presence of congestive heart failure, hypertension, age 75 years or older, and diabetes mellitus and by assigning 2 points for history of stroke or transient ischemic attack. Data from peer review organizations representing 7 states were used to assemble a National Registry of AF (NRAF) consisting of 1733 Medicare beneficiaries aged 65 to 95 years who had nonrheumatic AF and were not prescribed warfarin at hospital discharge.
MAIN OUTCOME MEASURE: Hospitalization for ischemic stroke, determined by Medicare claims data.
RESULTS: During 2121 patient-years of follow-up, 94 patients were readmitted to the hospital for ischemic stroke (stroke rate, 4.4 per 100 patient-years). As indicated by a c statistic greater than 0.5, the 2 existing classification schemes predicted stroke better than chance: c of 0.68 (95% confidence interval [CI], 0.65-0.71) for the scheme developed by the Atrial Fibrillation Investigators (AFI) and c of 0.74 (95% CI, 0.71-0.76) for the Stroke Prevention in Atrial Fibrillation (SPAF) III scheme. However, with a c statistic of 0.82 (95% CI, 0.80-0.84), the CHADS( 2) index was the most accurate predictor of stroke. The stroke rate per 100 patient-years without antithrombotic therapy increased by a factor of 1.5 (95% CI, 1.3-1.7) for each 1-point increase in the CHADS( 2) score: 1.9 (95% CI, 1.2-3.0) for a score of 0; 2.8 (95% CI, 2.0-3.8) for 1; 4.0 (95% CI, 3.1-5.1) for 2; 5.9 (95% CI, 4.6-7.3) for 3; 8.5 (95% CI, 6.3-11.1) for 4; 12.5 (95% CI, 8.2-17.5) for 5; and 18.2 (95% CI, 10.5-27.4) for 6.
CONCLUSION: The 2 existing classification schemes and especially a new stroke risk index, CHADS( 2), can quantify risk of stroke for patients who have AF and may aid in selection of antithrombotic therapy.

Abstract/Text: CONTEXT: Antiarrhythmic drugs are commonly used for prevention of recurrent atrial fibrillation (AF) despite inconsistent efficacy and frequent adverse effects. Catheter ablation has been proposed as an alternative treatment for paroxysmal AF.
OBJECTIVE: To determine the efficacy of catheter ablation compared with antiarrhythmic drug therapy (ADT) in treating symptomatic paroxysmal AF.
DESIGN, SETTING, AND PARTICIPANTS: A prospective, multicenter, randomized (2:1), unblinded, Bayesian-designed study conducted at 19 hospitals of 167 patients who did not respond to at least 1 antiarrhythmic drug and who experienced at least 3 AF episodes within 6 months before randomization. Enrollment occurred between October 25, 2004, and October 11, 2007, with the last follow-up on January 19, 2009.
INTERVENTION: Catheter ablation (n = 106) or ADT (n = 61), with assessment for effectiveness in a comparable 9-month follow-up period.
MAIN OUTCOME MEASURES: Time to protocol-defined treatment failure. The proportion of patients who experienced major treatment-related adverse events within 30 days of catheter ablation or ADT was also reported.
RESULTS: At the end of the 9-month effectiveness evaluation period, 66% of patients in the catheter ablation group remained free from protocol-defined treatment failure compared with 16% of patients treated with ADT. The hazard ratio of catheter ablation to ADT was 0.30 (95% confidence interval, 0.19-0.47; P < .001). Major 30-day treatment-related adverse events occurred in 5 of 57 patients (8.8%) treated with ADT and 5 of 103 patients (4.9%) treated with catheter ablation. Mean quality of life scores improved significantly in patients treated by catheter ablation compared with ADT at 3 months; improvement was maintained during the course of the study.
CONCLUSION: Among patients with paroxysmal AF who had not responded to at least 1 antiarrhythmic drug, the use of catheter ablation compared with ADT resulted in a longer time to treatment failure during the 9-month follow-up period.
TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT00116428.

Abstract/Text: BACKGROUND AND PURPOSE: The risk of stroke in patients with atrial fibrillation (AF) is not homogeneous, and various clinical risk factors have informed the development of stroke risk stratification schemes (RSS). Among anticoagulated cohorts, the emphasis should be on the identification of patients who remain at high risk for stroke despite anticoagulation.
METHODS: We investigated predictors of thromboembolism (TE) risk in an anticoagulated AF clinical trial cohort (n = 7329 subjects) and tested the predictive value of contemporary RSS in this cohort: CHADS₂, Framingham, NICE 2006, American College of Cardiology/American Heart Association/European Society of Cardiology 2006, the 8th American College of Chest Physicians guidelines and the CHA₂DS₂-VASc schemes.
RESULTS: On multivariate analysis, significant predictors of TE were stroke/TIA (hazard ratio [HR], 2.24; P < 0.001), age 75 years or older (HR, 1.77; P = 0.0002), coronary artery disease (HR, 1.52; P = 0.0047), and smoking (HR, 2.10; P = 0.0005), whereas reported alcohol use (HR, 0.70; P = 0.02) was protective. Comparison of contemporary RSS demonstrated variable classification of AF patients into risk strata, although c-statistics for TE were broadly similar among the RSS tested and varied between 0.575 (NICE 2006) and 0.647 (CHA₂DS₂-VASc). CHA₂DS₂-VASc classified 94.2% as being at high risk, whereas most other RSS categorized two-thirds as being at high risk. Of the 184 TE events, 181 (98.4%) occurred in patients identified as being at high risk by the CHA₂DS₂-VASc schema. There was a stepwise increase in TE with increasing CHA₂DS₂-VASc score (P (trend) < 0.0001), which had the highest HR (3.75) among the tested schemes. The negative predictive value (ie, the percent categorized as "not high risk" actually being free from TE) for CHA₂DS₂-VASc was 99.5%.
CONCLUSIONS: Coronary artery disease and smoking are additional risk factors for TE in anticoagulated AF patients, whereas alcohol use appears protective. Of the contemporary stroke RSS, the CHA₂DS₂-VASc scheme correctly identified the greatest proportion of AF patients at high risk, despite the similar predictive ability of most RSS evidenced by the c-statistic.

Abstract/Text: OBJECTIVE: Despite extensive use of oral anticoagulation (OAC) in patients with atrial fibrillation (AF) and the increased bleeding risk associated with such OAC use, no handy quantification tool for assessing this risk exists. We aimed to develop a practical risk score to estimate the 1-year risk for major bleeding (intracranial, hospitalization, hemoglobin decrease > 2 g/L, and/or transfusion) in a cohort of real-world patients with AF.
METHODS: Based on 3,978 patients in the Euro Heart Survey on AF with complete follow-up, all univariate bleeding risk factors in this cohort were used in a multivariate analysis along with historical bleeding risk factors. A new bleeding risk score termed HAS-BLED (Hypertension, Abnormal renal/liver function, Stroke, Bleeding history or predisposition, Labile international normalized ratio, Elderly (> 65 years), Drugs/alcohol concomitantly) was calculated, incorporating risk factors from the derivation cohort.
RESULTS: Fifty-three (1.5%) major bleeds occurred during 1-year follow-up. The annual bleeding rate increased with increasing risk factors. The predictive accuracy in the overall population using significant risk factors in the derivation cohort (C statistic 0.72) was consistent when applied in several subgroups. Application of the new bleeding risk score (HAS-BLED) gave similar C statistics except where patients were receiving antiplatelet agents alone or no antithrombotic therapy, with C statistics of 0.91 and 0.85, respectively.
CONCLUSION: This simple, novel bleeding risk score (HAS-BLED) provides a practical tool to assess the individual bleeding risk of real-world patients with AF, potentially supporting clinical decision making regarding antithrombotic therapy in patients with AF.

Abstract/Text: BACKGROUND: Recent data demonstrate promising effects on left ventricular dysfunction and left ventricular ejection fraction (LVEF) improvement following ablation for atrial fibrillation (AF) in patients with heart failure. We sought to study the relationship between LVEF, New York Heart Association class on presentation, and the end points of mortality and heart failure admissions in the CASTLE-AF study (Catheter Ablation for Atrial Fibrillation With Heart Failure) population. Furthermore, predictors for LVEF improvement were examined.
METHODS: The CASTLE-AF patients with coexisting heart failure and AF (n=363) were randomized in a multicenter prospective controlled fashion to ablation (n=179) versus pharmacological therapy (n=184). Left ventricular function and New York Heart Association class were assessed at baseline (after randomization) and at each follow-up visit.
RESULTS: In the ablation arm, a significantly higher number of patients experienced an improvement in their LVEF to >35% at the end of the study (odds ratio, 2.17; P<0.001). Compared with the pharmacological therapy arm, both ablation patient groups with severe (<20%) or moderate/severe (≥20% and <35%) baseline LVEF had a significantly lower number of composite end points (hazard ratio [HR], 0.60; P=0.006), all-cause mortality (HR, 0.54; P=0.019), and cardiovascular hospitalizations (HR, 0.66; P=0.017). In the ablation group, New York Heart Association I/II patients at the time of treatment had the strongest improvement in clinical outcomes (primary end point: HR, 0.43; P<0.001; mortality: HR, 0.30; P=0.001).
CONCLUSIONS: Compared with pharmacological treatment, AF ablation was associated with a significant improvement in LVEF, independent from the severity of left ventricular dysfunction. AF ablation should be performed at early stages of the patient's heart failure symptoms.

Abstract/Text: BACKGROUND: Atrial fibrillation (AF) and left ventricular systolic dysfunction (LVSD) frequently co-exist despite adequate rate control. Existing randomized studies of AF and LVSD of varying etiologies have reported modest benefits with a rhythm control strategy.
OBJECTIVES: The goal of this study was to determine whether catheter ablation (CA) for AF could improve LVSD compared with medical rate control (MRC) where the etiology of the LVSD was unexplained, apart from the presence of AF.
METHODS: This multicenter, randomized clinical trial enrolled patients with persistent AF and idiopathic cardiomyopathy (left ventricular ejection fraction [LVEF] ≤45%). After optimization of rate control, patients underwent cardiac magnetic resonance (CMR) to assess LVEF and late gadolinium enhancement, indicative of ventricular fibrosis, before randomization to either CA or ongoing MRC. CA included pulmonary vein isolation and posterior wall isolation. AF burden post-CA was assessed by using an implanted loop recorder, and adequacy of MRC was assessed by using serial Holter monitoring. The primary endpoint was change in LVEF on repeat CMR at 6 months.
RESULTS: A total of 301 patients were screened; 68 patients were enrolled between November 2013 and October 2016 and randomized with 33 in each arm (accounting for 2 dropouts). The average AF burden post-CA was 1.6 ± 5.0% at 6 months. In the intention-to-treat analysis, absolute LVEF improved by 18 ± 13% in the CA group compared with 4.4 ± 13% in the MRC group (p < 0.0001) and normalized (LVEF ≥50%) in 58% versus 9% (p = 0.0002). In those undergoing CA, the absence of late gadolinium enhancement predicted greater improvements in absolute LVEF (10.7%; p = 0.0069) and normalization at 6 months (73% vs. 29%; p = 0.0093).
CONCLUSIONS: AF is an underappreciated reversible cause of LVSD in this population despite adequate rate control. The restoration of sinus rhythm with CA results in significant improvements in ventricular function, particularly in the absence of ventricular fibrosis on CMR. This outcome challenges the current treatment paradigm that rate control is the appropriate strategy in patients with AF and LVSD. (Catheter Ablation Versus Medical Rate Control in Atrial Fibrillation and Systolic Dysfunction [CAMERA-MRI]; ACTRN12613000880741).

Copyright © 2017 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

Abstract/Text: BACKGROUND: Contemporary clinical risk stratification schemata for predicting stroke and thromboembolism (TE) in patients with atrial fibrillation (AF) are largely derived from risk factors identified from trial cohorts. Thus, many potential risk factors have not been included.
METHODS: We refined the 2006 Birmingham/National Institute for Health and Clinical Excellence (NICE) stroke risk stratification schema into a risk factor-based approach by reclassifying and/or incorporating additional new risk factors where relevant. This schema was then compared with existing stroke risk stratification schema in a real-world cohort of patients with AF (n = 1,084) from the Euro Heart Survey for AF.
RESULTS: Risk categorization differed widely between the different schemes compared. Patients classified as high risk ranged from 10.2% with the Framingham schema to 75.7% with the Birmingham 2009 schema. The classic CHADS(2) (Congestive heart failure, Hypertension, Age > 75, Diabetes, prior Stroke/transient ischemic attack) schema categorized the largest proportion (61.9%) into the intermediate-risk strata, whereas the Birmingham 2009 schema classified 15.1% into this category. The Birmingham 2009 schema classified only 9.2% as low risk, whereas the Framingham scheme categorized 48.3% as low risk. Calculated C-statistics suggested modest predictive value of all schema for TE. The Birmingham 2009 schema fared marginally better (C-statistic, 0.606) than CHADS(2). However, those classified as low risk by the Birmingham 2009 and NICE schema were truly low risk with no TE events recorded, whereas TE events occurred in 1.4% of low-risk CHADS(2) subjects. When expressed as a scoring system, the Birmingham 2009 schema (CHA(2)DS(2)-VASc acronym) showed an increase in TE rate with increasing scores (P value for trend = .003).
CONCLUSIONS: Our novel, simple stroke risk stratification schema, based on a risk factor approach, provides some improvement in predictive value for TE over the CHADS(2) schema, with low event rates in low-risk subjects and the classification of only a small proportion of subjects into the intermediate-risk category. This schema could improve our approach to stroke risk stratification in patients with AF.

Abstract/Text: BACKGROUND: Current guidelines recommend pulmonary-vein isolation by means of catheter ablation as treatment for drug-refractory paroxysmal atrial fibrillation. Radiofrequency ablation is the most common method, and cryoballoon ablation is the second most frequently used technology.
METHODS: We conducted a multicenter, randomized trial to determine whether cryoballoon ablation was noninferior to radiofrequency ablation in symptomatic patients with drug-refractory paroxysmal atrial fibrillation. The primary efficacy end point in a time-to-event analysis was the first documented clinical failure (recurrence of atrial fibrillation, occurrence of atrial flutter or atrial tachycardia, use of antiarrhythmic drugs, or repeat ablation) following a 90-day period after the index ablation. The noninferiority margin was prespecified as a hazard ratio of 1.43. The primary safety end point was a composite of death, cerebrovascular events, or serious treatment-related adverse events.
RESULTS: A total of 762 patients underwent randomization (378 assigned to cryoballoon ablation and 384 assigned to radiofrequency ablation). The mean duration of follow-up was 1.5 years. The primary efficacy end point occurred in 138 patients in the cryoballoon group and in 143 in the radiofrequency group (1-year Kaplan-Meier event rate estimates, 34.6% and 35.9%, respectively; hazard ratio, 0.96; 95% confidence interval [CI], 0.76 to 1.22; P<0.001 for noninferiority). The primary safety end point occurred in 40 patients in the cryoballoon group and in 51 patients in the radiofrequency group (1-year Kaplan-Meier event rate estimates, 10.2% and 12.8%, respectively; hazard ratio, 0.78; 95% CI, 0.52 to 1.18; P=0.24).
CONCLUSIONS: In this randomized trial, cryoballoon ablation was noninferior to radiofrequency ablation with respect to efficacy for the treatment of patients with drug-refractory paroxysmal atrial fibrillation, and there was no significant difference between the two methods with regard to overall safety. (Funded by Medtronic; FIRE AND ICE ClinicalTrials.gov number, NCT01490814.).

Abstract/Text: BACKGROUND: Atrial fibrillation (AF) and left ventricular systolic dysfunction (LVSD) frequently co-exist despite adequate rate control. Existing randomized studies of AF and LVSD of varying etiologies have reported modest benefits with a rhythm control strategy.
OBJECTIVES: The goal of this study was to determine whether catheter ablation (CA) for AF could improve LVSD compared with medical rate control (MRC) where the etiology of the LVSD was unexplained, apart from the presence of AF.
METHODS: This multicenter, randomized clinical trial enrolled patients with persistent AF and idiopathic cardiomyopathy (left ventricular ejection fraction [LVEF] ≤45%). After optimization of rate control, patients underwent cardiac magnetic resonance (CMR) to assess LVEF and late gadolinium enhancement, indicative of ventricular fibrosis, before randomization to either CA or ongoing MRC. CA included pulmonary vein isolation and posterior wall isolation. AF burden post-CA was assessed by using an implanted loop recorder, and adequacy of MRC was assessed by using serial Holter monitoring. The primary endpoint was change in LVEF on repeat CMR at 6 months.
RESULTS: A total of 301 patients were screened; 68 patients were enrolled between November 2013 and October 2016 and randomized with 33 in each arm (accounting for 2 dropouts). The average AF burden post-CA was 1.6 ± 5.0% at 6 months. In the intention-to-treat analysis, absolute LVEF improved by 18 ± 13% in the CA group compared with 4.4 ± 13% in the MRC group (p < 0.0001) and normalized (LVEF ≥50%) in 58% versus 9% (p = 0.0002). In those undergoing CA, the absence of late gadolinium enhancement predicted greater improvements in absolute LVEF (10.7%; p = 0.0069) and normalization at 6 months (73% vs. 29%; p = 0.0093).
CONCLUSIONS: AF is an underappreciated reversible cause of LVSD in this population despite adequate rate control. The restoration of sinus rhythm with CA results in significant improvements in ventricular function, particularly in the absence of ventricular fibrosis on CMR. This outcome challenges the current treatment paradigm that rate control is the appropriate strategy in patients with AF and LVSD. (Catheter Ablation Versus Medical Rate Control in Atrial Fibrillation and Systolic Dysfunction [CAMERA-MRI]; ACTRN12613000880741).

Copyright © 2017 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

Abstract/Text: BACKGROUND: Atrial fibrillation, the most common sustained cardiac arrhythmia and a major cause of stroke, results from simultaneous reentrant wavelets. Its spontaneous initiation has not been studied.
METHODS: We studied 45 patients with frequent episodes of atrial fibrillation (mean [+/-SD] duration, 344+/-326 minutes per 24 hours) refractory to drug therapy. The spontaneous initiation of atrial fibrillation was mapped with the use of multielectrode catheters designed to record the earliest electrical activity preceding the onset of atrial fibrillation and associated atrial ectopic beats. The accuracy of the mapping was confirmed by the abrupt disappearance of triggering atrial ectopic beats after ablation with local radio-frequency energy.
RESULTS: A single point of origin of atrial ectopic beats was identified in 29 patients, two points of origin were identified in 9 patients, and three or four points of origin were identified in 7 patients, for a total of 69 ectopic foci. Three foci were in the right atrium, 1 in the posterior left atrium, and 65 (94 percent) in the pulmonary veins (31 in the left superior, 17 in the right superior, 11 in the left inferior, and 6 in the right inferior pulmonary vein). The earliest activation was found to have occurred 2 to 4 cm inside the veins, marked by a local depolarization preceding the atrial ectopic beats on the surface electrocardiogram by 106+/-24 msec. Atrial fibrillation was initiated by a sudden burst of rapid depolarizations (340 per minute). A local depolarization could also be recognized during sinus rhythm and abolished by radiofrequency ablation. During a follow-up period of 8+/-6 months after ablation, 28 patients (62 percent) had no recurrence of atrial fibrillation.
CONCLUSIONS: The pulmonary veins are an important source of ectopic beats, initiating frequent paroxysms of atrial fibrillation. These foci respond to treatment with radio-frequency ablation.