C.R. is a 53-year-old man with persistent AF and a CHADS2 score of 2 (denoting the presence of hypertension and diabetes). His echocardiogram reveals mild to moderate left ventricular hypertrophy with a mildly dilated left atrial dimension, no pathologic valvular stenotic or regurgitant lesions, and preserved left ventricular systolic function. He does not want to take warfarin and wants to pursue heart rhythm control. The use of direct-current cardioversion in the absence of antiarrhythmic drug therapy was unsuccessful for him 1 year previously.
The AFFIRM (Atrial Fibrillation Follow-Up Investigation of Rhythm Management) trial,
13 a randomized, multicenter comparison trial evaluating the efficacy of heart rate control vs heart rhythm control as a strategy for the treatment of patients with AF is often cited as evidence that establishment of sinus rhythm is no better than rate-controlled AF in the care of patients. However, the AFFIRM trial predominantly enrolled older patients (mean age, 70 years), had relatively limited patient follow-up (average duration, 3.5 years), and produced findings that may not be generalizable to a younger population who potentially may require lifelong therapy. In addition, the study was a comparison of management strategies, not a trial that compared the effects of restoration of sinus rhythm in patients with AF. Many patients in the arm of the study assessing heart rate control maintained sinus rhythm. In a post hoc analysis of the AFFIRM trial,
14 sinus rhythm was associated with improved survival, and use of an antiarrhythmic agent was associated with an similar decrement in survival, suggesting that the beneficial effects of restoration of sinus rhythm may have been countered by the negative effects of antiarrhythmic drug therapy. The AFFIRM study did not consider catheter ablation as a factor in restoration of sinus rhythm. In the patient group randomized to follow a heart rhythm control strategy, discontinuation of anticoagulation therapy was associated with unacceptable stroke rates.
Figure 2 presents a flow diagram for maintenance of sinus rhythm based on clinical guidelines. Note that decision making is stratified based on the clinical characteristics of no (or minimal) heart disease, hypertension, coronary artery disease, or heart failure. C.R. has hypertension, so the next step for him involves determination of the presence of left ventricular hypertrophy. When substantial left ventricular hypertrophy is present, only the drug amiodarone is recommended. It should be noted that Canadian guidelines define left ventricular hypertrophy as being associated with electrocardiographic evidence of secondary ST- and T-wave changes,
15 whereas the American College of Cardiology/American Heart Association guidelines do not make this specific statement.
In the absence of substantial left ventricular hypertrophy, 4 choices of first-line antiarrhythmic agents (ie, dronedarone, flecainide, propafenone, and sotalol) are available for heart rhythm control. Because of the possibility that proarrhythmic adverse effects will develop, patients should be admitted to the hospital to initiate treatment with sotalol, whereas patients receiving any of the other 3 aforementioned first-line antiarrhythmic agents can start receiving treatment on an outpatient basis. Although treatment with flecainide or propafenone can be initiated on an outpatient basis, use of these agents should be avoided in patients with ischemic heart disease or left ventricular dysfunction.
For patients who have recurrence of AF while receiving treatment with 1 of these agents, alternative clinical options include considering a trial of a different antiarrhythmic drug, such as amiodarone or dofetilide, or attempting left atrial catheter ablation in the hope of curing AF. Given the number of qualifying statements regarding heart rhythm control, many primary care physicians defer decision making and the choice of treatment options to a cardiologist or electrophysiologist.
Although the guidelines for the management of AF were updated in 2011, advancements in the field of catheter ablation for the management of AF have occurred so rapidly that catheter ablation is an increasingly attractive treatment option for many patients. For patients with persistent AF, a randomized controlled trial
16 showed that, after 5 years of follow up, catheter ablation provided acceptable long-term relief notwithstanding a gradual decline in arrhythmia-free status. In addition, studies of patients with recurrent paroxysmal AF have shown that catheter ablation has reasonable efficacy, is associated with a longer time to treatment failure, and also decreases the likelihood of progression from paroxysmal AF to persistent AF, compared with pharmacologic treatment.
17,18 On the basis of findings from these studies and others, the American College of Cardiology/American Heart Association guidelines recommend catheter ablation as a reasonable treatment for patients with symptomatic persistent AF, provided that patients first tried to achieve sinus rhythm maintenance with the use of at least 1 antiarrhythmic agent (
Figure 3). An issue that is not addressed in the guidelines but should be individualized for each patient is whether it is reasonable to ask a 40-year-old patient with paroxysmal or persistent AF to take medication several times a day for the next 40 years to maintain sinus rhythm, or whether the patient should undergo an ablation procedure in the hopes of curing their arrhythmia.
Assume that C.R. has evidence of atrial flutter only, not AF. How might this assumption change his treatment recommendations? Recognize that typical atrial flutter is characterized by findings of saw-toothed P waves in the inferior leads on 12-lead electrocardiography. Although atrial flutter is a more organized arrhythmia
Catheter ablation is reasonable for symptomatic persistent atrial fibrillation.
characterized by electrical reentry within the right atrium, it carries risks for stroke similar to those associated with AF, and it should be treated according to the same standards with respect to anticoagulation therapy. Atrial flutter is unique, however, in that heart rate control is often more difficult to achieve than with AF. Furthermore, evidence has established that catheter ablation is superior to medical therapy rendering it a first-line therapy for most patients.
19 In addition, recent studies have suggested that even when durable elimination of atrial flutter can be achieved by catheter ablation, a significant portion of patients will eventually have AF develop.
20,21 Clinicians should, therefore, be vigilant in monitoring for the subsequent development of AF in patients for whom catheter ablation successfully resolved atrial flutter.
After catheter ablation is performed, it is important to consider when it is safe to discontinue anticoagulation therapy and when AF can be considered cured. The expert consensus statement of the Heart Rhythm Society on the use of catheter ablation for AF recommends follow-up of patients within 3 months after catheter ablation is performed and every 6 months thereafter for a minimum of 2 years.
22 Twelve-lead electrocardiography should be performed at each clinical visit, and event monitoring should be performed for evaluation of palpitations. Auto-triggered ambulatory event monitoring is recommended for the evaluation of asymptomatic recurrences. The guidelines do not address the issue of whether anticoagulation therapy can be discontinued on the basis of these follow-up methods. In clinical practice, discontinuation of anticoagulation therapy generally is considered after 3 to 6 months of follow-up, provided that there are no symptomatic recurrences and that auto-triggered event monitoring
does not identify asymptomatic recurrences. Patients with very high CHADS
2 scores of 5 or 6 and patients who have previously had a stroke may be at risk of stroke independent of AF recurrence and may wish to continue anticoagulation therapy indefinitely.