In recent years, physicians have debated whether certain AF patients (eg, those with persistent AF who are older and less symptomatic) are best treated with rate-controlling drugs, such as calcium channel blockers, beta-blockers, and digoxin, or with an approach that aims to restore and maintain sinus rhythm using antiarrhythmic drugs (AADs) and cardioversion. Initially, therapy for AF was guided towards a rhythm-control approach, but the results of the landmark Atrial Fibrillation Follow-up Investigation of Rhythm Management (AFFIRM)[11] trial found no significant difference in patient outcomes between the 2 treatment strategies – results that are consistent with the findings of the Pharmacological Intervention in Atrial Fibrillation (PIAF),[12] Strategies of Treatment of Atrial Fibrillation (STAF),[13] and Rate Control vs Electrical Cardioversion for Persistent Atrial Fibrillation (RACE)[14] trials (Table 1).
Table 1. Rate- vs Rhythm-Control Trials
| Trial (Year) | Patients Studied | Results |
| PIAF[12] (2000) | N = 225; persistent AF of 7 to 360 days in duration | - No difference in symptom improvement
- Rhythm patients had higher exercise tolerance but significantly higher rate of hospitalizations.
- Only 23% of patients taking amiodarone were in NSR at follow-up, although 56% of patients who were successfully cardioverted could be maintained in NSR.
- Amiodarone was discontinued in 25% of the rhythm patients due to drug side effects.
|
| AFFIRM[11] (2002) | N = 4060; > 65 years of age or who had other risk factors for stroke or death and had AF that was likely to recur
The study included patients with intermittent self-terminating episodes of AF and those who required cardioversion. | - At 5-year follow-up, 63% of rhythm patients were in NSR vs 34.6% of rate patients.
- No significant difference in the rate of death between the 2 groups (23.8% vs 21.3%; P = .08)
- The number of hospitalizations during follow-up was greater in the rhythm group (P < .001).
- The stroke rate was low (about 1% per year in both groups); majority of strokes occurred in patients who had stopped taking warfarin or whose INR was subtherapeutic at the time of the stroke.
|
| RACE[14] (2002) | N = 522; persistent AF after previous electrical cardioversion; mean age 68 years | - After mean follow-up of 2.3 years, there was no significant difference in the composite of cardiac death, heart failure, thromboembolic complications, bleeding, implantation of a pacemaker, and severe adverse drug effects.
- Overall results showed a trend for better outcomes in rate patients (17.2% vs 22.6%).
- Only 39% of rhythm patients were in NSR, and thromboembolic events were more likely in rhythm patients.
|
| STAF[13] (2003) | N = 200; persistent AF; 44.5% were 60-69 years of age and 79% had at least 1 risk factor. | - No difference in the combination of death, CPR, cerebrovascular event, and systemic embolism after 19.6 mos
- Rhythm group had significantly more hospitalizations.
- Rate group showed trend toward higher rate of mortality.
- Most primary endpoints occurred in AF; only 1 occurred in NSR, shortly after cardioversion.
- The percentage of patients who were in NSR in the rhythm group after up to 4 cardioversions was 23% at 36 mos.
|
AF = atrial fibrillation; AFFIRM = Atrial Fibrillation Follow-up Investigation of Rhythm Management; CPR = cardiopulmonary resuscitation; INR = international normalized ratio; NSR = normal sinus rhythm; PIAF = Pharmacological Intervention in Atrial Fibrillation; RACE = Rate Control vs Electrical Cardioversion for Persistent Atrial Fibrillation; STAF = Strategies of Treatment of Atrial Fibrillation
AFFIRM[11] randomized 4060 patients with intermittent (mildly symptomatic) AF and at least 1 risk factor for stroke to a rate-control or rhythm-control strategy. Baseline characteristics were well balanced between the 2 groups; mean age was 69.7 years; and 39.3% and 38.2% of patients had hypertension and coronary artery disease, respectively. In 69.2% of patients, the qualifying episode of AF lasted > 2 minutes and approximately 35% of patients were enrolled following their first episode of AF. At 5-year follow-up, there was no mortality benefit associated with rhythm control (23.8% vs 21.3%; P = .08). However, rhythm-control patients were more likely to be hospitalized than those in the rate-control arm (80.1% vs 73.0%; P < .001), and only 63% of patients in this group were actually able to maintain normal sinus rhythm over the 5-year follow-up. Stroke rates were similar in both rhythm- and rate-control arms (8.9% vs 7.4%; P .93), and strokes occurred most frequently in patients who had stopped their anticoagulation medication altogether or who were on medication but were not adequately anticoagulated (ie, had international normalized ratios [INR] <>
Similar findings were demonstrated in the STAF[13] and RACE[14] randomized studies. However, the results of all of these trials can only be applied to the fairly limited group of patients enrolled -- primarily older AF patients (> 65 years of age) who are mildly symptomatic. Thus, a rate-control strategy may not be the best option for all AF patients, particularly younger patients, those with first-onset AF or poor left ventricular function, or those who are highly symptomatic.
Copyright © 2006 Medscape.
