The AFFIRM trial: main trial and substudies-what can We expect?

Perceived effects on patients' health of participation in the atrial fibrillation follow-up investigation of rhythm management study

BACKGROUND

Patients' views about participation in clinical trials have been explored using end-of-study questionnaires for various disease entities. However, little is known about why individuals with atrial fibrillation (AF) choose to participate in clinical trials or how they view their research experience. Understanding these perceptions should provide valuable information for future studies in developing methods to enhance enrollment, optimize adherence to therapies, and maximize patient retention.

METHODS

The Atrial Fibrillation Follow-up Investigation of Rhythm Management (AFFIRM) Study was a randomized trial of rate-control versus rhythm-control for the management of AF. This descriptive ancillary study used a 7-item questionnaire comprising closed and open-ended items that explored: (1) perceptions of benefits from participation, (2) motivation for enrolling, and (3) satisfaction with research staff and operations.

RESULTS

A total of 741/1,032 participants (72%) at 34 of 213 participating AFFIRM sites responded, representing 18% of the 4,060 patients enrolled. The mean follow-up of these respondents was 3.8 +/- 1.1 years. Most respondents (91%) felt that they received enough information about AFFIRM before enrolling and that the results would benefit themselves (88%) and others (91%). Most respondents felt study participation improved awareness about AF (90%) and facilitated coordination of their healthcare (89%). Virtually all were satisfied with information received from AFFIRM personnel (96%), and most (98%) reported that they had received "good care." Responses were similar between randomization groups (rate-control or rhythm-control) and between those younger than 65 years and those 65 years or older. Participants in sinus rhythm at last follow-up were more likely to believe that their medical care in AFFIRM was better than what they would otherwise have received, and were more likely to perceive their treatment course as entailing fewer emergency room visits, hospitalizations, and doctor visits. Regularly scheduled appointments and ongoing availability of staff to answer questions appeared to increase participants' confidence and reduce anxiety.

CONCLUSIONS

Patients enrolled in a long-term clinical trial for management of AF were overwhelmingly satisfied with participation.

Acute anticoagulation adjustment in patients with atrial fibrillation at risk for stroke: approaches, strategies, risks and benefits

The acute management of anticoagulation in patients with atrial fibrillation to prevent stroke and other thromboembolic complications includes the use of individualized strategies tailored to the patient and based on the situation (cardioversion, surgeries, dental procedures, cardiac interventions, other invasive procedures and initiation of, or adjustment to, warfarin dosing). The vast range of choices can cause confusion and few randomized controlled clinical trials in this area provide adequate guidance. Chronic anticoagulation management is more straightforward since clinical evidence is ample, randomized clinical trial data provides cogent informaiton and guidelines have been established. Acute management of anticoagulation in patients with atrial fibrillation to prevent thromboembolic complications is often unrecognized but is emerging as a crucial, but challenging, and increasingly complex aspect of the care of patients with atrial fibrillation. This review addresses issues regarding such patients who may be at risk for stroke and require acute adjustments of anticoagulation (in light of, or in lieu of, chronic anticoagulation). Several promising new strategies are considered in light of established medical care. This analysis provides practical recommendations based on available data and presents results from recent investigations that may provide insight into future strategies.

Functional Status in Rate- Versus Rhythm-Control Strategies for Atrial Fibrillation

OBJECTIVES

The Atrial Fibrillation Follow-up Investigation of Rhythm Management (AFFIRM) functional status substudy aimed to test the hypothesis that functional status is similar in rate-control and rhythm-control strategies.

BACKGROUND

Randomized studies, including the AFFIRM study, have failed to demonstrate survival benefits between rate-control and rhythm-control strategies for atrial fibrillation (AF). However, AF may cause functional capacity or cognitive impairment that might justify maintenance of sinus rhythm.

METHODS

Investigators of the AFFIRM study enrolled 4,060 patients with AF who required long-term therapy and who were 65 years of age or older or who had another risk factor for stroke or death. New York Heart Association functional class (NYHA-FC) and Canadian Cardiovascular Society Angina Classification were assessed at initial and each follow-up visit. From 22 randomly chosen functional status substudy sites, 245 participants underwent 6-min walk tests and Mini-Mental State Examination (MMSE) at initial, two-month, and yearly visits. Patients were assigned randomly to rate-controlling drugs, allowing AF to persist, or rhythm-controlling antiarrhythmic drugs, to maintain sinus rhythm.

RESULTS

The NYHA-FC worsened with time in both rate-control and rhythm-control groups, with no differences between groups. Presence of AF was associated with worse NYHA-FC (p < 0.0001). No differences were observed in Canadian Cardiovascular Society Angina Classification or MMSE scores. Six-minute walk distance improved over time in both study arms. On average, walk distance was 94 feet greater in the rhythm-control group (adjusted p = 0.049).

CONCLUSIONS

Modest improvement in 6-min walk distance was noted in the rhythm-control arm. Presence of AF was associated with worse NYHA-FC. No difference in cognitive function was detected.

Influence of the randomized trials, AFFIRM and RACE, on the management of atrial fibrillation in two University Medical Centers

The results of the Atrial Fibrillation Follow-Up Investigation of Rhythm Management (AFFIRM) and the Rate Control Versus Electrical Cardioversion for Persistent Atrial Fibrillation (RACE) study were presented in March 2002. These large studies showed no benefit of a rhythm-control strategy over a rate-control strategy in managing atrial fibrillation (AF). Cardioversion and atrioventricular junctional ablation are forms of rhythm control and rate control, respectively. The numbers of cardioversions and atrioventricular junctional ablations performed at the University of Virginia and the Medical College of Virginia during the 52 months before AFFIRM and RACE results were released and the 21 months afterward were compared. From January 1998 to March 2002, monthly averages of 31 +/- 8 elective cardioversions and 6 +/- 3 atrioventricular junctional ablations were performed; from April 2002 to December 2003, the monthly averages were 21 +/- 6 cardioversions (p = 0.001) and 9 +/- 3 ablations (p = 0.001). AF management changed at these institutions shortly after the RACE and AFFIRM results were released.

The Atrial Fibrillation Follow-up Investigation of Rhythm Management (AFFIRM) study

OBJECTIVES

We sought to evaluate approaches used to control rate, the effectiveness of rate control, and switches from one drug class to another in the Atrial Fibrillation Follow-up Investigation of Rhythm Management (AFFIRM) study.

BACKGROUND

The AFFIRM study showed that atrial fibrillation (AF) can be treated effectively with rate control and anticoagulation, but drug efficacy to control rate remains uncertain.

METHODS

Patients (n = 2,027) randomized to rate control in the AFFIRM study were given rate-controlling drugs by their treating physicians. Standardized rate-control efficacy criteria developed a priori included resting heart rate and 6-min walk tests and/or ambulatory electrocardiographic results.

RESULTS

Average follow-up was 3.5 +/- 1.3 years. Initial treatment included a beta-adrenergic blocker (beta-blocker) alone in 24%, a calcium channel blocker alone in 17%, digoxin alone in 16%, a beta-blocker and digoxin in 14%, or a calcium channel blocker and digoxin in 14% of patients. Overall rate control was achieved in 70% of patients given beta-blockers as the first drug (with or without digoxin), 54% with calcium channel blockers (with or without digoxin), and 58% with digoxin alone. Adequate overall rate control was achieved in 58% of patients with the first drug or combination. Multivariate analysis revealed an association between first drug class and several clinical variables. There were more changes to beta-blockers than to the other two-drug classes (p < 0.0001).

CONCLUSIONS

Rate control in AF is possible in the majority of patients with AF. Beta-blockers were the most effective drugs. To achieve the goal of adequate rate control in all patients, frequent medication changes and drug combinations were needed.

Implications for Nursing Care of Patients With Atrial Fibrillation

Atrial fibrillation is the most common sustained cardiac dysrhythmia treated in North America and Europe. As such, it is one of the current epidemics in cardiovascular disease. Findings from the AFFIRM (Atrial Fibrillation Follow-up: Investigation of Rhythm Management) and RACE (RAte Control versus Electrical cardioversion for persistent atrial fibrillation) clinical trials are presented and the current evidence for the management of atrial fibrillation using anticoagulation, rate-control, and rhythm-control strategies is outlined. Implications for nurses are discussed including physiologic and psychosocial interventions.

Effects of coupled pacing on cardiac performance during acute atrial tachycardia and fibrillation: an old therapy revisited for a new reason

Atrial tachycardia (AT) and fibrillation (AF) result in rapid ventricular rates that are detrimental to optimal cardiac function. The purpose of this study was to determine whether the application of a coupled pacing (CP) regimen would improve ventricular function by decreasing the ventricular rate of mechanical contractions (VRMCs). We simulated AT by pacing either atrium at a rate that resulted in a rapid but regular ventricular rate in seven anesthetized dogs. AF was induced by increasing the atrial pacing rate until atrial activation did not follow the pacing. After the induction of either AT or AF, we applied CP after each intrinsic ventricular activation. We measured the VRMCs and left ventricular (LV) pressures and volumes via a pressure-conductance catheter. The marked reductions in VRMCs during CP resulted in increases in LV end-diastolic volume. The CP resulted in virtually no mechanical contractions, whereas the strength of contractions from the normal electrical activation increased. The increases in the positive LV rate of pressure development over time and LV ejection fraction during CP were the result of postextrasystolic potentiation. The average stroke work (area of the pressure-volume loops) increased as a result of CP during both AT and AF. Despite the large increases in stroke volume (approximately 2x) during CP, the changes in cardiac output were moderate because the VRMCs markedly decreased (approximately 1/2). We conclude that CP therapy may be a viable therapy for slowing the heart rate and improving cardiac performance in patients with AT and AF.

Randomized trial of rate-control versus rhythm-control in persistent atrial fibrillation: the Strategies of Treatment of Atrial Fibrillation (STAF) study

OBJECTIVES

This study was designed to compare two treatment strategies in patients with atrial fibrillation(AF): rhythm-control (restoration and maintenance of sinus rhythm) and rate-control (pharmacologic or invasive rate-control and anticoagulation).

BACKGROUND

Atrial fibrillation is the most common arrhythmia. It is unclear whether a strategy of rhythm- or rate-control is better in terms of mortality, morbidity, and quality of life.

METHODS

The Strategies of Treatment of Atrial Fibrillation (STAF) multicenter pilot trial randomized 200 patients (100 per group) with persistent AF to rhythm- or rate-control. The combined primary end point was a combination of death, cardiopulmonary resuscitation, cerebrovascular event, and systemic embolism.

RESULTS

After 19.6 +/- 8.9 months (range 0 to 36 months) there was no difference in the primary end point between rhythm-control (9/100; 5.54%/year) and rate-control (10/100; 6.09%/year; p = 0.99). The percentage of patients in sinus rhythm in the rhythm-control group after up to four cardioversions during the follow-up period (rate-control group) was 23% (0%) at 36 months. Eighteen primary end points occurred in atrial fibrillation; only one occurred in sinus rhythm (p = 0.049).

CONCLUSIONS

The STAF pilot study showed no differences between the two treatment strategies in all end points except hospitalizations. These data suggest that there was no benefit in attempting rhythm-control in these patients with a high risk of arrhythmia recurrence. It remains unclear whether the results in the rhythm-control group would have been better if sinus rhythm had been maintained in a higher proportion of patients, as all but one end point occurred during AF.

Echocardiographic changes and predictors of arrhythmia recurrence after long-term use of the atrial defibrillator

BACKGROUND

The patient-activated atrial defibrillator allows patients to cardiovert themselves from atrial fibrillation soon after the onset of symptoms. The long-term effects of early cardioversion from persistent atrial fibrillation on left ventricular performance and left atrial size are unknown.

METHODS

Eighteen patients, mean age 63.4, 83% male, had the Jewel((R)) AF atrial defibrillator implanted for persistent atrial fibrillation only. Transthoracic echocardiography was performed 3-monthly following implant. Parasternal long axis measurements were taken using conventional M-mode techniques.

RESULTS

Over follow-up of 28.0+/-9 months, 377 episodes of persistent atrial fibrillation were terminated by patient-activated cardioversion (median 15 per patient). Echocardiographic measurements at implant were; left atrium 44+/-6 mm, left ventricular end-diastolic diameter 49+/-7 mm, left ventricular end-systolic diameter 34+/-7 mm, fractional shortening 33+/-10% and ejection fraction 65+/-17%. After 1 year there had been a significant decrease in mean left atrial size to 41+/-6 mm (P=0.02) and an increase in mean ejection fraction to 73+/-8% (P=0.04). At long-term follow-up however, all parameters reverted to pre-implant levels. Baseline echocardiographic variables did not predict which patients would demonstrate serial increases in sinus rhythm duration between shocks during long-term follow-up. Patients on antiarrhythmic drug therapy however were more likely to demonstrate "sinus rhythm begetting sinus rhythm".

CONCLUSIONS

Use of the atrial defibrillator for spontaneous persistent atrial fibrillation is associated with a medium-term (1 year) reduction in left atrial size and an increase in ejection fraction. These changes were not maintained in the long-term. Synergistic therapy with antiarrhythmic drugs may prolong periods of sinus rhythm between arrhythmia recurrences.

Anticoagulation in management of atrial fibrillation

Atrial fibrillation is the most common cardiac arrhythmia in adults. The prevalence of atrial fibrillation rises with age, reaching as high as 9% in those 70 years and older. Currently there are 2.2 million affected people in the United States, with twice the mortality rate of age-matched controls in sinus rhythm. Epidemiologic studies show atrial fibrillation to be responsible for as many as 15% of the total number of strokes, a higher incidence of dementia, cardiac function compromise, and decreased quality of life. Recent studies indicate that rate control and rhythm restoration are equally effective strategies in the treatment of atrial fibrillation, with a trend toward better survival in patients treated for rate control and anticoagulation. Data from several randomized controlled studies on stroke prophylaxis provided consistent evidence of the superiority of adjusted-dose warfarin over aspirin. Guidelines developed by the American College of Cardiology, the American Heart Association, the European Society of Cardiology, and ACCP provide a convenient decision-making framework for the practicing physician. The safety and effectiveness of anticoagulation in clinical practice were found to be equal to those in major trials with rigorous controls. Despite the proven effectiveness and safety of oral anticoagulation for thromboembolism prophylaxis in atrial fibrillation, warfarin remains underused, especially among the elderly (75 years and older), who are at the greatest risk of stroke and would likely benefit the most from prophylactic anticoagulation.

Electrical cardioversion for atrial fibrillation and flutter

BACKGROUND

Atrial fibrillation increases the risk of stroke, increases the risk of cognitive impairment, and adversely affects cardiovascular haemodynamics. Electrical cardioversion for atrial fibrillation has been in use since the 1960s; the rationale is that restoration of sinus rhythm improves cardiovascular haemodynamics, reduces the risk of stroke, and obviates the need for long-term anticoagulation.

OBJECTIVES

To assess the effects of electrical cardioversion of atrial fibrillation or atrial flutter on the annual risk of thromboembolic events, strokes and mortality (primary outcomes measures), the rate of cognitive decline, quality of life, the use of anticoagulants and the risk of re-hospitalisation (secondary outcome measures) in adults (>18 years) with acute, paroxysmal or sustained atrial fibrillation or atrial flutter, of any duration and any aetiology.

SEARCH STRATEGY

One reviewer searched the Cochrane Controlled Clinical Trials Register (2000 Issue 4), MEDLINE (1966 to December 2000), EMBASE (1980 to December 2000), CINAHL (1982 to November 2000) and proceedings of the American College of Cardiology (published in the Journal of the American College of Cardiology 1983 to 2000). Reference lists of articles were searched. Personal contact was made with experts in the field. A second reviewer handsearched proceedings of the British Cardiac Society (published in British Heart Journal (1980 to 1995) and in Heart (1995 to May 2001); proceedings of the European Congress of Cardiology and meetings of the Joint Working Groups of the European Society of Cardiology (published in European Heart Journal 1983-2000); scientific sessions of the American Heart Association (published in Circulation 1990-2000).

SELECTION CRITERIA

Randomised controlled trial or controlled clinical trials of electrical cardioversion plus 'usual care' versus 'usual care' only, where 'usual care' included any combination of the following: anticoagulants, antiplatelet drugs and drugs for 'rate control', in adults (>18 years) with acute, paroxysmal or sustained atrial fibrillation or atrial flutter, of any duration and any aetiology.

DATA COLLECTION AND ANALYSIS

It was planned to extract study data onto data extraction forms. The planned analysis was by the statistical package in RevMan.

MAIN RESULTS

No completed randomised trials or controlled clinical trials of electrical cardioversion were found. Two ongoing trials were identified.

REVIEWER'S CONCLUSIONS

There were no data from completed randomised controlled trials or controlled clinical trials to either support or refute the use of electrical cardioversion for atrial fibrillation. Randomised trials of electrical cardioversion are required.