Surveillance for Outcomes Selected as Atrial Fibrillation Quality Indicators in Canada: 10-Year Trends in Stroke, Major Bleeding, and Heart Failure

Background

Whether advances in identification and management of atrial fibrillation and atrial flutter (collectively, AF) have led to improved outcomes is unclear. We sought to study trends in clinical outcomes selected as quality indicators for nonvalvular AF in Canada.

Methods

We identified hospitalized patients with a first diagnosis of nonvalvular AF between April 2006 and March 2015, in all of Canada except Quebec. We assessed trends in 1-year incidence of stroke/systemic embolism (SSE), major bleeding, and initial heart failure (HF) hospitalization.

Results

The cohort included 466,476 patients. The median age was 77 years (interquartile range, 68-84 years), 46% were female, and 68% had a Congestive Heart Failure, Hypertension, Age (≥75 years), Diabetes, Stroke/Transient Ischemic Attack, Vascular Disease, Age (65-74 years), Sex (Female) (CHA₂DS₂-VASc) score > 3. Within 1 year of discharge, 3.5% were hospitalized for stroke or SSE, 1.6% for major bleeding, and 8.6% for new HF. Over the study period, the crude rate of SSE declined from 3.6% to 3.3% (P = 0.002), whereas the rates of hospitalization for new HF and for major bleeding did not significantly change. After adjustment for CHA₂DS₂-VASc score, the yearly rates of incident SSE (risk ratio, 0.99; 95% confidence interval [CI], 0.98-0.99; P = 0.002) and HF (risk ratio, 0.99; 95% CI, 0.99-1.00; P = 0.001) declined ≤ 1% absolute, whereas major bleeding remained unchanged (risk ratio, 1.00; 95% CI, 0.99-1.00; P = 0.28).

Conclusions

Among hospitalized patients with nonvalvular AF in Canada, the rate of SSE and new HF decreased modestly over a 10-year period, with no significant change in major bleeding. Efforts to study process-based quality indicators, with increased focus on HF prevention, are needed.

The 2020 Canadian Cardiovascular Society/Canadian Heart Rhythm Society Comprehensive Guidelines for the Management of Atrial Fibrillation

The Canadian Cardiovascular Society (CCS) atrial fibrillation (AF) guidelines program was developed to aid clinicians in the management of these complex patients, as well as to provide direction to policy makers and health care systems regarding related issues. The most recent comprehensive CCS AF guidelines update was published in 2010. Since then, periodic updates were published dealing with rapidly changing areas. However, since 2010 a large number of developments had accumulated in a wide range of areas, motivating the committee to complete a thorough guideline review. The 2020 iteration of the CCS AF guidelines represents a comprehensive renewal that integrates, updates, and replaces the past decade of guidelines, recommendations, and practical tips. It is intended to be used by practicing clinicians across all disciplines who care for patients with AF. The Grading of Recommendations, Assessment, Development and Evaluations (GRADE) system was used to evaluate recommendation strength and the quality of evidence. Areas of focus include: AF classification and definitions, epidemiology, pathophysiology, clinical evaluation, screening and opportunistic AF detection, detection and management of modifiable risk factors, integrated approach to AF management, stroke prevention, arrhythmia management, sex differences, and AF in special populations. Extensive use is made of tables and figures to synthesize important material and present key concepts. This document should be an important aid for knowledge translation and a tool to help improve clinical management of this important and challenging arrhythmia.

Temporal Trends in Population Rates of Incident Atrial Fibrillation and Atrial Flutter Hospitalizations, Stroke Risk, and Mortality Show Decline in Hospitalizations

BACKGROUND

Hospitalization for nonvalvular atrial fibrillation (NVAF) is common and results in substantial cost burden. Current national data trends for the incidence, stroke risk profiles, and mortality of hospitalization for NVAF and atrial flutter (AFL) are sparse.

METHODS

The Canadian Institute of Health Information Discharge Abstract Database was used to identify patients ≥ 20 years with incident NVAF/AFL (NVAF, ICD-9 code 427.3 or ICD-10 I48) in any diagnosis field from 2006 to 2015 in Canada, except Québec. National and provincial trends in rate over time (rate ratio, 95% confidence interval [CI]) were calculated for age-sex standardized hospitalizations. Trends in stroke risk profiles and in-hospital mortality rates adjusted for stroke risk factors were also calculated.

RESULTS

A total of 578,947 patients were hospitalized with incident NVAF/AFL. The median age was 77 years (interquartile range: 68-84), 82% were ≥ 65 years, 54% were men, 54% had a CHADS2 ≥ 2, and 69% had a CHA2DS2-Vasc ≥ 3. The overall age- and sex-standardized rate of NVAF/AFL hospitalization was 315 per 100,000 population and declined by 2% per year (P < 0.001). There was an annual rate decline in NVAF/AFL hospitalizations in every province. The majority of hospitalized patients are at high risk of stroke, and this risk remained unchanged. The average adjusted in-hospital mortality was 8.80 per 100 patients 95% CI, 8.80-8.81 with a 2% annual decline in rate (P < 0.001).

CONCLUSION

Between 2006 and 2015, we found national and provincial hospitalization rates for incident NVAF/AFL are declining. The majority of patients are at high risk for stroke. In-hospital mortality has declined but remains substantial.

2018 Focused Update of the Canadian Cardiovascular Society Guidelines for the Management of Atrial Fibrillation

The Canadian Cardiovascular Society (CCS) Atrial Fibrillation Guidelines Committee provides periodic reviews of new data to produce focused updates that address clinically important advances in atrial fibrillation (AF) management. This 2018 Focused Update addresses: (1) anticoagulation in the context of cardioversion of AF; (2) the management of antithrombotic therapy for patients with AF in the context of coronary artery disease; (3) investigation and management of subclinical AF; (4) the use of antidotes for the reversal of non-vitamin K antagonist oral anticoagulants; (5) acute pharmacological cardioversion of AF; (6) catheter ablation for AF, including patients with concomitant AF and heart failure; and (7) an integrated approach to the patient with AF and modifiable cardiovascular risk factors. The recommendations were developed using the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) standards. Individual studies and literature were reviewed for quality and bias; the literature review process and evidence tables are included as Supplementary Material and are available on the CCS Web site. Details of the updated recommendations are presented, along with their background and rationale. This document is linked to an updated summary of all CCS AF guidelines recommendations, from 2010 to the present 2018 Focused Update, which is provided in the Supplementary Material.

The Optimal Anti-Coagulation for Enhanced-Risk Patients Post-Catheter Ablation for Atrial Fibrillation (OCEAN) trial

BACKGROUND

The optimal long-term antithrombotic regimen for patients after successful catheter-based atrial fibrillation (AF) ablation is not well defined. Presently, practice variation exists, and the benefits of oral anticoagulation over antiplatelet therapy across the entire spectrum of stroke risk profile remain undefined in the postablation population. To date, there are no randomized trials to inform clinicians on this therapeutic question.

OBJECTIVE

The objective was to assess whether rivaroxaban is superior to acetylsalicylic acid (ASA) in reducing the risk of clinically overt stroke, systemic embolism, or covert stroke among patients without apparent recurrent atrial arrhythmias for at least 1 year after their most recent AF ablation procedure.

METHODS/DESIGN

A prospective, multicenter, open-label, randomized trial with blinded assessment of outcomes is under way (NCT02168829). Atrial fibrillation patients with at least 1 stroke risk factor (as defined by the CHA₂DS₂-VASc score) and without known atrial arrhythmia recurrences for at least 12 months after ablation are randomized to rivaroxaban 15 mg or ASA 75-160 mg daily. The primary outcome is a composite of clinically overt stroke, systemic embolism, and covert stroke based on brain magnetic resonance imaging. Key secondary outcomes include major bleeding outcomes, intracranial hemorrhage, transient ischemic attack, neuropsychological testing, quality of life, and an economic analysis. Subjects will be followed for 3 years. The estimated overall sample size is 1,572 subjects (786 per arm).

DISCUSSION

The OCEAN trial is a multicenter randomized controlled trial evaluating 2 antithrombotic treatment strategies for patients with risk factors for stroke after apparently successful AF ablation. We hypothesize that rivaroxaban will reduce the occurrence of clinically overt stroke, systemic embolism, and covert stroke when compared with ASA alone.

Temporal Patterns and Predictors of Rate vs Rhythm Control in Patients Attending a Multidisciplinary Atrial Fibrillation Clinic

BACKGROUND

Contemporary trends in the selection of and persistence with rate vs rhythm control for atrial fibrillation (AF) are not well studied, particularly in the context of multidisciplinary AF clinics.

METHODS

The initial arrhythmia management strategy in 1031 consecutive patients attending a multidisciplinary AF clinic from 2005-2012 was analyzed.

RESULTS

The 397 (38.5%) patients initially treated with rhythm control were younger (57.4 ± 14 years vs 65.6 ± 13 years; P < 0.0001) and more likely to be men (64.5% vs 56.9%; P = 0.019). They also had fewer comorbidities, lower CHADS₂ (Congestive Heart Failure, Hypertension, Age, Diabetes, Stroke/Transient Ischemic Attack) scores, and greater symptom burden. The proportion treated with rhythm control declined from 46.9% in 2005-2006 to 28.4% in 2012 (P for trend < 0.0001). Compared with those initially selecting rate control, patients treated with rhythm control required more frequent clinic encounters (7 [interquartile range {IQR}, 3-12] vs 3 [IQR, 2-7]; P < 0.001) and longer follow-up (266 days [IQR, 84-548 days] vs 99 days [IQR, 0-313 days]; P < 0.001). Younger age, absence of diabetes and sleep apnea, earlier treatment year, higher symptom burden, and rural residence were independently associated with rhythm control. Persistence with the initial treatment strategy was reduced in the rhythm-control group (P = 0.003).

CONCLUSIONS

Use of rhythm control as the initial arrhythmia management strategy for AF in a specialty AF clinic is declining. Rhythm control requires more intensive follow-up and was more likely to lead to a change in arrhythmia management strategy.

The Development and Feasibility Assessment of Canadian Quality Indicators for Atrial Fibrillation

In 2010, the Canadian Cardiovascular Society embarked on an initiative to develop pan-Canadian quality indicators (QIs) and standardized data definitions with the ultimate goal of monitoring, comparing, and contrasting national cardiovascular care and its outcomes. One of the first working groups to be established was tasked with identifying and then defining a set of QIs for atrial fibrillation/flutter (AF/AFL). The Canadian Cardiovascular Society "Best Practices for Developing Cardiovascular Quality Indicators" methodology was used to develop an initial catalogue of 25 QIs intended to measure critical issues around access, process, and outcomes relating to AF/AFL management. This list was subsequently pared down to 5 QIs felt to have the greatest relative importance for quality assurance and measurability so as to facilitate early adoption. Three of these QIs were finally selected to assess the feasibility of their measurement using existing administrative datasets. These were the number of patients with a diagnosis of nonvalvular AF/AFL at high risk of stroke (75 years or older, or CHADS₂ ≥ 2) receiving an oral anticoagulant, and the rates of stroke and major haemorrhage in patients with nonvalvular AF/AFL according to CHA₂DS₂-VASc score and anticoagulant use. Despite their clear importance in assessing AF/AFL care, none of these 3 QIs were found to be readily measurable across Canada using existing national datasets. Investment in new medical data infrastructure is required to facilitate regular monitoring of QIs to improve cardiovascular care.

Systolic blood pressure and mortality in patients with atrial fibrillation and heart failure: insights from the AFFIRM and AF-CHF studies

AIMS

To investigate the association between baseline systolic blood pressure levels and mortality in patients with AF with or without LV dysfunction. Hypertension leads to cardiovascular disease but, in specific groups, low blood pressure has been associated with a paradoxical increase in mortality. In patients with AF and heart failure, the relationship between blood pressure and death remains largely unknown.

METHODS AND RESULTS

We conducted a post-hoc combined analysis on pooled data from AFFIRM and AF-CHF trials and assessed the relationship between baseline systolic blood pressure (SBP) and mortality and hospitalizations. Patients were classified according to LVEF (>40%, ≤40%) and baseline SBP (<120 mmHg, 120-140 mmHg, >140 mmHg). A total of 5436 patients with non-permanent AF were followed for 41 ± 16 months. In patients with LVEF >40%, baseline SBP was not related to mortality using multivariate Cox regression analyses to adjust for baseline differences (P = 0.563). In contrast, in patients with LVEF ≤40% (n = 1980), SBP <120 mmHg and SBP >140 mmHg were both associated with a significant increase in total mortality compared with SBP 120-140 mmHg [hazard ratio (HR) 1.75, 95% confidence interval (CI) 1.41-2.17; and HR 1.40, 95% CI 1.04-1.90, respectively]. Hospitalizations were unrelated to SBP regardless of LVEF.

CONCLUSIONS

Mortality is modulated by baseline SBP levels in patients with AF and depressed EF but not in patients with normal EF. Targeted therapy of AF patients based on SBP merits further prospective investigation.

Lone atrial fibrillation: does it exist?

The historical origin of the term "lone atrial fibrillation" (AF) predates by 60 years our current understanding of the pathophysiology of AF, the multitude of known etiologies for AF, and our ability to image and diagnose heart disease. The term was meant to indicate AF in patients for whom subsequent investigations could not demonstrate heart disease, but for many practitioners has become synonymous with "idiopathic AF." As the list of heart diseases has expanded and diagnostic techniques have improved, the prevalence of lone AF has fallen. The legacy of the intervening years is that definitions of lone AF in the literature are inconsistent so that studies of lone AF are not comparable. Guidelines provide a vague definition of lone AF but do not provide direction about how much or what kind of imaging and other testing are necessary to exclude heart disease. There has been an explosion in the understanding of the pathophysiology of AF in the last 20 years in particular. Nevertheless, there are no apparently unique mechanisms for AF in patients categorized as having lone AF. In addition, the term "lone AF" is not invariably useful in making treatment decisions, and other tools for doing so have been more thoroughly and carefully validated. It is, therefore, recommended that use of the term "lone AF" be avoided.

Detection of previously undiagnosed atrial fibrillation in patients with stroke risk factors and usefulness of continuous monitoring in primary stroke prevention

The detection of undiagnosed atrial tachycardia/atrial fibrillation (AT/AF) among patients with stroke risk factors could be useful for primary stroke prevention. We analyzed newly detected AT/AF (NDAF) using continuous monitoring in patients with stroke risk factors but without previous stroke or evidence of AT/AF. NDAF (AT/AF >5 minutes on any day) was determined in patients with implantable cardiac rhythm devices and ≥1 stroke risk factors (congestive heart failure, hypertension, age ≥75 years, or diabetes). All devices were capable of continuously monitoring the daily cumulative time in AT/AF. Of 1,368 eligible patients, NDAF was identified in 416 (30%) during a follow-up of 1.1 ± 0.7 years and was unrelated to the CHADS(2) score (congestive heart failure, hypertension [blood pressure consistently >140/90 mm Hg or hypertension treated with medication], age ≥75 years, diabetes mellitus, previous stroke or transient ischemic attack). The presence of AT/AF >6 hours on ≥1 day increased significantly with increased CHADS(2) scores and was present in 158 (54%) of 294 patients with NDAF and a CHADS(2) score of ≥2. NDAF was sporadic, and 78% of patients with a CHADS(2) score of ≥2 with NDAF experienced AT/AF on <10% of the follow-up days. The median interval to NDAF detection in these higher risk patients was 72 days (interquartile range 13 to 177). In conclusion, continuous monitoring identified NDAF in 30% of patients with stroke risk factors. In patients with NDAF, AT/AF occurred sporadically, highlighting the difficulty in detecting paroxysmal AT/AF using traditional monitoring methods. However, AT/AF also persisted for >6 hours on ≥1 days in most patients with NDAF and multiple stroke risk factors. Whether patients with CHADS(2) risk factors but without a history of AF might benefit from implantable monitors for the selection and administration of anticoagulation for primary stroke prevention merits additional investigation.

Usefulness of vernakalant hydrochloride injection for rapid conversion of atrial fibrillation

The objective of the present study was to assess the safety and effectiveness of vernakalant hydrochloride injection (RSD1235), a novel antiarrhythmic drug, for the conversion of atrial fibrillation (AF) or atrial flutter to sinus rhythm (SR). Patients with either AF or atrial flutter were randomized in a 1:1 ratio to receive vernakalant (n = 138) or placebo (n = 138) and were stratified by an arrhythmia duration of >3 hours to ≤7 days (short duration) and 8 to ≤45 days (long duration). The first infusion of placebo or vernakalant (3 mg/kg) was given for 10 minutes followed by a second infusion of placebo or vernakalant (2 mg/kg) 15 minutes later if the arrhythmia had not terminated. A total of 265 patients were randomized and received treatment. The primary end point was conversion of AF to SR for ≥1 minute within 90 minutes of the start of the drug infusion in the short-duration AF group. Of the 86 patients receiving vernakalant in the short-duration AF group, 44 (51.2%) demonstrated conversion to SR compared to 3 (3.6%) of the 84 in the placebo group (p <0.0001). The median interval to conversion of short-duration AF to SR in the responders given vernakalant was 8 minutes. Of the entire AF population (short- and long-duration AF), 47 (39.8%) of the 118 vernakalant patients experienced conversion of AF to SR compared to 4 (3.3%) of the 121 placebo patients (p <0.0001). Transient dysgeusia and sneezing were the most common adverse events in the vernakalant patients. One vernakalant patient who had severe aortic stenosis experienced hypotension and ventricular fibrillation and died. In conclusion, vernakalant demonstrated a rapid and high rate of conversion for short-duration AF and was well tolerated.

Incidence of newly detected atrial arrhythmias via implantable devices in patients with a history of thromboembolic events

BACKGROUND AND PURPOSE

Evidence of atrial tachycardia/atrial fibrillation (AT/AF) is often sought in patients with ischemic stroke or transient ischemic attack. We studied patients with previous thromboembolic events (TE) who were implanted with devices capable of continuous arrhythmia monitoring to comprehensively quantify the incidence and duration of newly detected AT/AF.

METHODS

This study represents a subgroup analysis of the TRENDS trial, which included patients with clinical indications for pacemakers or defibrillators and >or=1 stroke risk factors (heart failure, hypertension, age 65 or older, diabetes, or previous TE). A history of AF was not required. All implanted devices were capable of continuously monitoring the cumulative time spent in AT/AF each day. This analysis focuses primarily on the incidence and duration of newly detected AT/AF (defined as >or=5 minutes of AT/AF on any day) in patients with previous TE, no documented history of AF, and no warfarin or antiarrhythmic drug use.

RESULTS

A total of 319 patients had a history of TE and >or=1 day of device data. Patients with a documented history of AF (n=80), warfarin use (n=56), or antiarrhythmic drug use (n=20) were excluded from analysis. Of the remaining 163 patients, newly detected AT/AF was identified via the device in 45 patients (28%) over a mean follow-up of 1.1+/-0.7 years. AT/AF recurred infrequently, with only 12 patients experiencing AT/AF on >10% of follow-up days.

CONCLUSIONS

Newly detected episodes of AT/AF were found via continuous monitoring in 28% of patients with previous TE. Most episodes would not have been detected by standard intermittent monitoring techniques.

The relationship between daily atrial tachyarrhythmia burden from implantable device diagnostics and stroke risk: the TRENDS study

BACKGROUND

It is unknown if brief episodes of device-detected atrial fibrillation (AF) increase thromboembolic event (TE) risk.

METHODS AND RESULTS

TRENDS was a prospective, observational study enrolling patients with > or = 1 stroke risk factor (heart failure, hypertension, age > or = 65 years, diabetes, or prior TE) receiving pacemakers or defibrillators that monitor atrial tachycardia (AT)/AF burden (defined as the longest total AT/AF duration on any given day during the prior 30-day period). This time-varying exposure was updated daily during follow-up and related to TE risk. Annualized TE rates were determined according to AT/AF burden subsets: zero, low (<5.5 hours [median duration of subsets with nonzero burden]), and high (> or = 5.5 hours). A multivariate Cox model provided hazard ratios including terms for stroke risk factors and time-varying AT/AF burden and antithrombotic therapy. Patients (n=2486) had at least 30 days of device data for analysis. During a mean follow-up of 1.4 years, annualized TE risk (including transient ischemic attacks) was 1.1% for zero, 1.1% for low, and 2.4% for high burden subsets of 30-day windows. Compared with zero burden, adjusted hazard ratios (95% CIs) in the low and high burden subsets were 0.98 (0.34 to 2.82, P=0.97) and 2.20 (0.96 to 5.05, P=0.06), respectively.

CONCLUSIONS

The TE rate was low compared with patients with traditional AF with similar risk profiles. The data suggest that TE risk is a quantitative function of AT/AF burden. AT/AF burden > or = 5.5 hours on any of 30 prior days appeared to double TE risk. Additional studies are needed to more precisely investigate the relationship between stroke risk and AT/AF burden.

Validation of a New Simple Scale to Measure Symptoms in Atrial Fibrillation

Background— Atrial fibrillation (AF) is commonly associated with impaired quality of life. There is no simple validated scale to quantify the functional illness burden of AF. The Canadian Cardiovascular Society Severity in Atrial Fibrillation (CCS-SAF) scale is a bedside scale that ranges from class 0 to 4, from no effect on functional quality of life to a severe effect on life quality. This study was performed to validate the scale.

Methods and Results— In 484 patients with documented AF (62.2�12.5 years of age, 67% men; 62% paroxysmal and 38% persistent/permanent), the SAF class was assessed and 2 validated quality-of-life questionnaires were administered: the SF-36 generic scale and the disease-specific AFSS (University of Toronto Atrial Fibrillation Severity Scale). There is a significant linear graded correlation between the SAF class and measures of symptom severity, physical and emotional components of quality of life, general well-being, and health care consumption related to AF. Patients with SAF class 0 had age- and sex-standardized SF-36 scores of 0.15�0.16 and −0.04�0.31 (SD units), that is, units away from the mean population score for the mental and physical summary scores, respectively. For each unit increase in SAF class, there is a 0.36 and 0.40 SD unit decrease in the SF-36 score for the physical and mental components. As the SAF class increases from 0 to 4, the symptom severity score (range, 0 to 35) increases from 4.2�5.0 to 18.4�7.8 ( P <0.0001).

Conclusions— The CCS-SAF scale is a simple semiquantitative scale that closely approximates patient-reported subjective measures of quality of life in AF and may be practical for clinical use.

Prevention of atrial fibrillation: report from a national heart, lung, and blood institute workshop

The National Heart, Lung, and Blood Institute convened an expert panel April 28 to 29, 2008, to identify gaps and recommend research strategies to prevent atrial fibrillation (AF). The panel reviewed the existing basic scientific, epidemiological, and clinical literature about AF and identified opportunities to advance AF prevention research. After discussion, the panel proposed the following recommendations: (1) enhance understanding of the epidemiology of AF in the population by systematically and longitudinally investigating symptomatic and asymptomatic AF in cohort studies; (2) improve detection of AF by evaluating the ability of existing and emerging methods and technologies to detect AF; (3) improve noninvasive modalities for identifying key components of cardiovascular remodeling that promote AF, including genetic, fibrotic, autonomic, structural, and electrical remodeling markers; (4) develop additional animal models reflective of the pathophysiology of human AF; (5) conduct secondary analyses of already-completed clinical trials to enhance knowledge of potentially effective methods to prevent AF and routinely include AF as an outcome in ongoing and future cardiovascular studies; and (6) conduct clinical studies focused on secondary prevention of AF recurrence, which would inform future primary prevention investigations.

Clinical criteria for predicting benefit of ICD/PM in post myocardial infarction patients: an AVID and CAST analysis

BACKGROUND

Three clinical factors from the Antiarrhythmics Versus Implantable Defibrillators (AVID) trial-heart failure, left ventricular dysfunction and certain historical features defined a subgroup in which an implantable cardioverter defibrillator (ICD/PM) has a mortality advantage over amiodarone.

METHODS

These three factors were jointly evaluated in the AVID cohort with ischemic heart disease (IHD) and the results applied in placebo-treated post-infarction patients in the cardiac arrhythmia suppression trial (CAST).

RESULTS

Similar predictive power was noted in AVID patients with IHD. In CAST the factors defined three groups; one group (5.8%), corresponding to AVID patients that had high risk and benefited from an ICD/PM and another group (17.2%) corresponding to patients in AVID where the risk was moderate and ICD/PM and amiodarone had equal efficacy, demonstrated a two-fold higher risk of sudden arrhythmic than non-arrhythmic death and hence would be expected to benefit from antiarrhythmia therapy. The third group, corresponding to AVID patients with low risk of arrhythmia, demonstrated similar and low risks of sudden arrhythmic and non-arrhythmic death. Thus this group (77%) is unlikely to benefit from indiscriminate antiarrhythmia therapy. Onset of risk of death in CAST patients was offset from randomization by 3 to 6 months.

CONCLUSIONS

Readily available clinical criteria identify a small group likely to benefit from an ICD/PM after recent myocardial infarction (MI) and the remainder unlikely to benefit from nonselective ICD/PM therapy. Additional risk stratification should focus on the latter patients and be timed to allow ICD/PM implantation between 2 and 6 months after MI.

Rhythm control versus rate control for atrial fibrillation and heart failure

BACKGROUND

It is common practice to restore and maintain sinus rhythm in patients with atrial fibrillation and heart failure. This approach is based in part on data indicating that atrial fibrillation is a predictor of death in patients with heart failure and suggesting that the suppression of atrial fibrillation may favorably affect the outcome. However, the benefits and risks of this approach have not been adequately studied.

METHODS

We conducted a multicenter, randomized trial comparing the maintenance of sinus rhythm (rhythm control) with control of the ventricular rate (rate control) in patients with a left ventricular ejection fraction of 35% or less, symptoms of congestive heart failure, and a history of atrial fibrillation. The primary outcome was the time to death from cardiovascular causes.

RESULTS

A total of 1376 patients were enrolled (682 in the rhythm-control group and 694 in the rate-control group) and were followed for a mean of 37 months. Of these patients, 182 (27%) in the rhythm-control group died from cardiovascular causes, as compared with 175 (25%) in the rate-control group (hazard ratio in the rhythm-control group, 1.06; 95% confidence interval, 0.86 to 1.30; P=0.59 by the log-rank test). Secondary outcomes were similar in the two groups, including death from any cause (32% in the rhythm-control group and 33% in the rate-control group), stroke (3% and 4%, respectively), worsening heart failure (28% and 31%), and the composite of death from cardiovascular causes, stroke, or worsening heart failure (43% and 46%). There were also no significant differences favoring either strategy in any predefined subgroup.

CONCLUSIONS

In patients with atrial fibrillation and congestive heart failure, a routine strategy of rhythm control does not reduce the rate of death from cardiovascular causes, as compared with a rate-control strategy. (ClinicalTrials.gov number, NCT00597077.)

Vernakalant Hydrochloride for Rapid Conversion of Atrial Fibrillation

Background— The present study assessed the efficacy and safety of vernakalant hydrochloride (RSD1235), a novel compound, for the conversion of atrial fibrillation (AF).

Methods and Results— Patients were randomized in a 2:1 ratio to receive vernakalant or placebo and were stratified by AF duration of 3 hours to 7 days (short duration) and 8 to 45 days (long duration). A first infusion of placebo or vernakalant (3 mg/kg) was given for 10 minutes, followed by a second infusion of placebo or vernakalant (2 mg/kg) 15 minutes later if AF was not terminated. The primary end point was conversion of AF to sinus rhythm for at least 1 minute within 90 minutes of the start of drug infusion in the short-duration AF group. A total of 336 patients were randomized and received treatment (short duration, n=220; long duration, n=116). Of the 145 vernakalant patients, 75 (51.7%) in the short-duration AF group converted to sinus rhythm (median time, 11 minutes) compared with 3 of the 75 placebo patients (4.0%; P <0.001). Overall, in the short- and long-duration AF groups, 83 of the 221 vernakalant patients (37.6%) experienced termination of AF compared with 3 of the 115 placebo patients (2.6%; P <0.001). Transient dysgeusia and sneezing were the most common side effects in vernakalant-treated patients. Four vernakalant-related serious adverse events (hypotension [2 events], complete atrioventricular block, and cardiogenic shock) occurred in 3 patients.

Conclusion— Vernakalant demonstrated rapid conversion of short-duration AF and was well tolerated.

Comparison of idraparinux with vitamin K antagonists for prevention of thromboembolism in patients with atrial fibrillation: a randomised, open-label, non-inferiority trial

BACKGROUND

Vitamin K antagonists, the current standard treatment for prophylaxis against stroke and systemic embolism in patients with atrial fibrillation, require regular monitoring and dose adjustment; an unmonitored, fixed-dose anticoagulant regimen would be preferable. The aim of this randomised, open-label non-inferiority trial was to compare the efficacy and safety of idraparinux with vitamin K antagonists.

METHODS

Patients with atrial fibrillation at risk for thromboembolism were randomly assigned to receive either subcutaneous idraparinux (2.5 mg weekly) or adjusted-dose vitamin K antagonists (target of an international normalised ratio of 2-3). Assessment of outcome was done blinded to treatment. The primary efficacy outcome was the cumulative incidence of all stroke and systemic embolism. The principal safety outcome was clinically relevant bleeding. Analyses were done by intention to treat; the non-inferiority hazard ratio was set at 1.5. This trial is registered with ClinicalTrials.gov, number NCT00070655.

FINDINGS

The trial was stopped after randomisation of 4576 patients (2283 to receive idraparinux, 2293 to receive vitamin K antagonists) and a mean follow-up period of 10.7 (SD 5.4) months because of excess clinically relevant bleeding with idraparinux (346 cases vs 226 cases; 19.7 vs 11.3 per 100 patient-years; p<0.0001). There were 21 instances of intracranial bleeding with idraparinux and nine with vitamin K antagonists (1.1 vs 0.4 per 100 patient-years; p=0.014); elderly patients and those with renal impairment were at greater risk of such complications. There were 18 cases of thromboembolism with idraparinux and 27 cases with vitamin K antagonists (0.9 vs 1.3 per 100 patient-years; hazard ratio 0.71, 95% CI 0.39-1.30; p=0.007), satisfying the non-inferiority criterion. There were 62 deaths with idraparinux and 61 with vitamin K anatagonists (3.2 vs 2.9 per 100 patient-years; p=0.49).

INTERPRETATION

In patients with atrial fibrillation at risk for thromboembolism, long-term treatment with idraparinux was no worse than vitamin K antagonists in terms of efficacy, but caused significantly more bleeding.

Monitoring the ACTIVE-W trial: some issues in monitoring a noninferiority trial

Noninferiority comparisons of new to current therapies and the use of composite outcomes represent significant advances in the design of clinical trials. They increasingly characterize trials of new cardiovascular agents, posing new challenges to Data Safety Monitoring Boards (DSMB) and principal investigators. The ACTIVE-W study was a noninferiority comparison of the combination of clopidogrel and acetylsalicylic acid versus oral anticoagulant among patients with atrial fibrillation. When unexpectedly high rates of stroke and then of the composite outcome of stroke, non-central nervous system systemic embolism, myocardial infarction, and vascular death emerged, the DSMB modified its monitoring plan and conducted its first formal interim analysis much earlier than had been planned in the DSMB charter. The study was terminated when only 27% of the anticipated outcomes had occurred. This paper discusses issues of appropriate stopping guidelines for noninferiority trials and the early emergence of significant harm in relation to one component (stroke) of a composite outcome. Conditional power was not determined concurrently with the HRs during the monitoring of ACTIVE-W; however, the members of the DSMB now believe that such calculations should be considered as useful adjuncts to the calculation of HRs and could lead to earlier termination of noninferiority trials whose interim results suggest futility, without the need for convincing proof of harm.

Atrial fibrillation: challenges and opportunities

Atrial fibrillation (AF) is the most common sustained arrhythmia encountered in clinical practice. There are many pharmacological and nonpharmacological options available for AF patients. There is, however, a great deal of dissatisfaction with the available treatments of this arrhythmia. Furthermore, AF management remains associated with many challenges that make the treatment of AF a vexing problem. The present overview discusses these challenges and explores the opportunities associated with them.

Medical management of atrial fibrillation

Atrial fibrillation (AF) is the most common sustained tachyarrhythmia encountered in clinical practice. The management of AF remains associated with many challenges that make its treatment a vexing problem. However, in recent years extraordinary progress has been made in the understanding and management of AF. In general, antiarrhythmic drugs for rhythm control have been disappointing. We have a better understanding of pharmacologic cardioversion and this has led to newer strategies, such as intermittent therapy. Several studies have been completed comparing pharmacologic rhythm control with pharmacologic heart rate control. There is also an emerging body of evidence concerning the value of adjunctive drug use for rhythm control using drugs that would not usually be considered to be antiarrhythmic. Finally, antithrombotic therapy is an increasingly important part of the medical management of AF. This article summarizes the results of many of the recent publications and their clinical implications concerning management of this common rhythm disorder.

Anticoagulation in atrial fibrillation: a contemporary viewpoint

Anticoagulation therapy in patients with atrial fibrillation is important. This review consists of three parts: chronic anticoagulation, anticoagulation for cardioversion, and a brief comment on anticoagulation around the time of left atrial radiofrequency ablation. The risk stratification scheme of the American College of Cardiology/American Heart Association/European Society of Cardiology (ACC/AHA/ESC) guidelines for chronic anticoagulation is briefly reviewed. Although there are several other similar schemes, they are not identical. The key point is the balance between benefit and risk. Some emerging controversies are outlined. Two specific questions explored are: is well-controlled hypertension a risk factor, and does paroxysmal atrial fibrillation confer the same risk as continuous atrial fibrillation? Differences in the risk of bleeding while taking a vitamin K antagonist noted in recent compared with older data are discussed. Risk of bleeding in the elderly and combined antithrombotic therapy with a vitamin K antagonist and an antiplatelet agent in high-risk patients are briefly discussed. Recent failures of studies attempting to find a suitable alternative to vitamin K antagonists are outlined. The treatment guidelines for anticoagulation for cardioversion are briefly reviewed. The risk of thromboembolism according to international normalized ratio and use of low-molecular-weight heparin as an alternative to warfarin are discussed. Anticoagulation before and after left atrial radiofrequency ablation is empirical, and long-term anticoagulation seems advisable for high risk patients at the present time. The two most pressing needs for further investigation are (1) clarification, simplification, and consolidated of risk stratification schemes and treatment recommendations and (2) discovery of alternatives to warfarin.

Does intensity of rate-control influence outcome in atrial fibrillation? An analysis of pooled data from the RACE and AFFIRM studies

AIMS

The AFFIRM and RACE studies showed that rate control is an acceptable treatment strategy for atrial fibrillation (AF). We examined whether strict rate control offers benefit over more lenient rate control.

METHODS AND RESULTS

We compared the outcome of patients enrolled in the rate-control arms of AFFIRM and RACE, using data from patients who met a composite of overlapping inclusion and exclusion criteria. We evaluated 1091 patients, 874 from AFFIRM and 217 from RACE. In AFFIRM, the rate-control strategy aimed for a resting heart rate < or =80 bpm and heart rate during daily activity of < or =110 bpm. In RACE, a more lenient approach was taken: resting heart rate <100 bpm. Primary endpoint was a composite of mortality, cardiovascular hospitalization, and myocardial infarction. Mean heart rate across all follow-up visits for patients in AF was lower in AFFIRM (76.1 vs. 83.4 bpm). Event-free survival for the occurrence of the primary endpoint did not differ (64% in AFFIRM vs. 66% in RACE). Patients with mean heart rates during AF within the AFFIRM (< or =80) or RACE (<100) criteria had a better outcome than patients with heart rates > or =100 (hazard ratios 0.69 and 0.58, respectively, for < or =80 and <100 compared with > or =100 bpm).

CONCLUSION

Stringency of the approach to rate control, based on the comparison of the AFFIRM and RACE studies, was not associated with an important difference in clinical events.

A novel, simple scale for assessing the symptom severity of atrial fibrillation at the bedside: the CCS-SAF scale

BACKGROUND

The severity of symptoms caused by atrial fibrillation (AF) is extremely variable. Quantifying the effect of AF on patient well-being is important but there is no simple, commonly accepted measure of the effect of AF on quality of life (QoL). Current QoL measures are cumbersome and impractical for clinical use.

OBJECTIVE

To create a simple, concise and readily usable AF severity score to facilitate treatment decisions and physician communication.

METHODS

The Canadian Cardiovascular Society (CCS) Severity of Atrial Fibrillation (SAF) Scale is analogous to the CCS Angina Functional Class. The CCS-SAF score is determined using three steps: documentation of possible AF-related symptoms (palpitations, dyspnea, dizziness/syncope, chest pain, weakness/fatigue); determination of symptom-rhythm correlation; and assessment of the effect of these symptoms on patient daily function and QoL. CCS-SAF scores range from 0 (asymptomatic) to 4 (severe impact of symptoms on QoL and activities of daily living). Patients are also categorized by type of AF (paroxysmal versus persistent/permanent). The CCS-SAF Scale will be validated using accepted measures of patient-perceived severity of symptoms and impairment of QoL and will require 'field testing' to ensure its applicability and reproducibility in the clinical setting.

CONCLUSIONS

This type of symptom severity scale, like the New York Heart Association Functional Class for heart failure symptoms and the CCS Functional Class for angina symptoms, trades precision and comprehensiveness for simplicity and ease of use at the bedside. A common language to quantify AF severity may help to improve patient care.

Pharmacologic approaches to rhythm versus rate control in atrial fibrillation—where are we now?

Until recently, contemporary drug treatment of atrial fibrillation (AF) focused primarily on restoration and maintenance of sinus rhythm, predicated on the belief that if AF is abolished then problems associated with AF would be abolished too. Recently completed clinical trials using drug therapy and comparing maintenance of sinus rhythm with control of ventricular rate have challenged this assumption, showing that simple control of ventricular rate with anticoagulation is an acceptable primary therapy, notably in older patients with persistent AF, minimally symptomatic or asymptomatic, and at increased risk for thromboembolic events. However, rate control and anticoagulation is not a panacea; existing trial results should not be interpreted to mean all patients should be treated with the rate control approach. Despite the limited efficacy and poor safety of current antiarrhythmic drugs, strategies for maintenance of sinus rhythm remain justified in many patients, such as those with first-episode AF, highly symptomatic patients, younger patients, and those with a history of congestive heart failure (CHF). Commonly used current and some investigational agents designated for "rhythm control" have enough pharmacologic overlap with rate control agents to be considered to have a dual mode of action, simultaneously addressing both rhythm and rate control. Furthermore, there is much interest in non-pharmacologic therapies, such as radiofrequency ablation, for rhythm control. The lack of appropriately designed and controlled trials at this time makes it difficult to determine the place of radiofrequency ablation and its impact on the rhythm versus rate question.

Rationale and design of a prospective study of the clinical significance of atrial arrhythmias detected by implanted device diagnostics: The TRENDS study

BACKGROUND

Sustained atrial fibrillation (AF) is a common risk factor for stroke. While intermittent AF also appears to pose a substantial stroke risk, the quantitative relationship between the percentage of time spent in AF and stroke risk is poorly specified and "intermittent" AF is not the same as paroxysmal AF. Improved assessment of the impact of AF burden on stroke risk will allow more targeted and safer use of antithrombotic therapy.

METHODS AND RESULTS

The primary objective of this study is to determine if AT/AF (all device detected atrial tachyarrhythmias, including atrial flutter, atrial fibrillation, and atrial tachycardia) burden over a 30 day period is an independent predictor of the occurrence of ischemic stroke, transient ischemic attack (TIA) and/or systemic embolism in subjects not receiving anticoagulation therapy. TRENDS is a prospective, post-market, non-randomized, multicenter study designed to enroll 3100 subjects who have an independent Class I/II indication for cardiac rhythm device implantation and who have demographic features suggestive of an increased risk for thromboembolic complications related to AT/AF. All implanted devices will have the ability to collect long-term AT/AF burden trending data and will be equivalently programmed to ensure consistent data collection. All subjects will be followed with device interrogations every 3 months and clinic visits every 6 months for 1 year. Subjects with a documented history of AT/AF prior to enrollment and those who develop AT/AF during the 12-month follow-up will be followed until the last subject enrolled in the study has completed their 24-month follow-up.

CONCLUSIONS

The results of the TRENDS study should help clarify the implications of data retrieved from an implantable device with regard to the risk for thromboembolic complications from atrial arrhythmias, even in the absence of symptoms.