The central pharmacologic decision in AF management, whether to control ventricular rate alone or to attempt restoration and maintenance of sinus rhythm, has been shaped by three landmark trials spanning two decades. The clinical context, patient age, symptom burden, and structural substrate all influence this decision.¹

The Atrial Fibrillation Follow-up Investigation of Rhythm Management trial randomized 4,060 patients (mean age 70 years, high stroke risk) to rate control vs. rhythm control. At 5 years, there was no significant difference in overall mortality (primary endpoint). Rhythm control was associated with more hospitalizations and a higher rate of adverse drug effects. The rhythm control arm included many patients on amiodarone, whose toxicity profile contributed to the adverse event burden.¹ The AFFIRM interpretation that dominated clinical practice for a decade was that rate control is a reasonable default strategy for most patients. However, subsequent post-hoc analyses showed that patients who actually achieved and maintained sinus rhythm had better outcomes, suggesting the strategy was sound but the available drugs were inadequate.

The Rate Control versus Electrical Cardioversion trial (RACE) similarly demonstrated non-inferiority of rate control to rhythm control for the composite endpoint of death, heart failure, thromboembolic complications, bleeding, pacemaker implantation, and adverse drug effects in 522 patients with persistent AF. Rate control was associated with fewer adverse drug effects.²

The Early Rhythm Control in Atrial Fibrillation trial reframed the rate vs. rhythm debate by focusing on early rhythm control in newly diagnosed AF. The trial randomized 2,789 patients (diagnosed with AF within the preceding 12 months) to early rhythm control (antiarrhythmic drugs or ablation) vs. usual care. Early rhythm control significantly reduced the composite of cardiovascular death, stroke, and hospitalization for HF or acute coronary syndrome (hazard ratio 0.79; 95% CI 0.66–0.94).³ The EAST-AFNET 4 findings suggest that early intervention before AF-induced atrial remodeling becomes irreversible improves outcomes, a mechanistic insight that shifts the clinical posture from reactive rate management to proactive early rhythm control in appropriate patients.

Current Strategic Framework: When to Pursue Rhythm Control

Symptomatic AF despite adequate rate control (palpitations, dyspnea, reduced exercise tolerance) Newly diagnosed AF (≤12 months) with cardiovascular risk factors (EAST-AFNET 4 population) AF-induced cardiomyopathy (tachycardia-mediated cardiomyopathy), rhythm control may reverse LV dysfunction Younger patients (≤65 years) where long-term maintenance of sinus rhythm is feasible Patient preference after informed discussion of options, risks, and success rates Rate control alone: older patients with minimal symptoms, long-standing persistent AF, high drug toxicity risk

The selection of a rhythm control agent is primarily determined by the presence and type of structural heart disease, with safety constraints derived from the CAST trial, ANDROMEDA, PALLAS, and SWORD trial findings discussed in preceding modules. A systematic stepwise approach based on cardiac substrate is essential.^4,5

In patients without structural disease, the full range of rhythm control agents is pharmacologically available. The choice is guided by side effect profile, QT interval, renal function, and patient preference:⁵ Flecainide 100–150 mg BD or propafenone 150–300 mg TID: First-line for younger patients with high symptom burden and no structural disease. Highly effective for paroxysmal AF. Require concurrent AV nodal blocking agent. Relatively contraindicated if LVH >1.4 cm. Sotalol 80–160 mg BD: Alternative with combined Class II/III activity. Requires QTc assessment (<450 ms) and renal function check. In-hospital initiation or re-initiation required. Dronedarone 400 mg BD: Acceptable in patients with paroxysmal or persistent AF without HFrEF or permanent AF. ATHENA data supports reduction in cardiovascular hospitalization. Amiodarone: Most effective but reserved for refractory cases or when other agents are contraindicated, due to cumulative toxicity risk.

Class Ic agents are contraindicated. CAST-derived evidence prohibits flecainide and propafenone. Sotalol (with adequate EF and renal function), dofetilide, and amiodarone are the agents of choice.^4,5 Dronedarone is acceptable if EF is preserved and the patient has not been recently hospitalized for HF.

The most pharmacologically restricted population. Only amiodarone and dofetilide have demonstrated safety. Flecainide, propafenone, sotalol, and dronedarone are contraindicated or carry mortality signals.^4,5 Catheter ablation is increasingly preferred as first-line rhythm control in symptomatic AF with HFrEF (CASTLE-AF trial: ablation vs. medical therapy reduced all-cause mortality and AF burden).

Class Ic agents are relatively contraindicated in significant LVH due to the proarrhythmic substrate created by altered conduction and fibrosis. Amiodarone

is the preferred agent; sotalol and dofetilide are alternatives depending on QT and renal function.⁴

Drug Selection Summary

In summary: patients with no structural heart disease may use flecainide, propafenone, sotalol, dronedarone, or amiodarone, with no specific agents contraindicated. Patients with CAD or prior MI with preserved EF should use sotalol, dofetilide, dronedarone (with preserved EF), or amiodarone; flecainide and propafenone are contraindicated. Patients with HFrEF (EF below 40%) should use only amiodarone or dofetilide; flecainide, propafenone, sotalol, and dronedarone are all contraindicated or carry mortality signals. Patients with significant LVH (wall thickness greater than 1.4 cm) should use amiodarone as preferred, with sotalol or dofetilide as alternatives if QT and renal function permit; flecainide and propafenone are relatively contraindicated.

Cardioversion of AF — pharmacologic or electrical, carries a 1–5% risk of systemic thromboembolism from dislodgement of left atrial appendage (LAA) thrombus if anticoagulation is inadequate. Anticoagulation management is therefore inseparable from cardioversion planning.⁸

AF of definite onset within the preceding 48 hours carries a low immediate thromboembolic risk (insufficient time for LAA thrombus formation). In this window, cardioversion may be performed after initiating anticoagulation (DOAC or therapeutic heparin), without requiring prolonged pre-cardioversion anticoagulation. Post-cardioversion anticoagulation for at least 4 weeks is mandatory regardless of CHA2DS2-VASc score, because atrial stunning (mechanical dysfunction persisting after electrical or pharmacologic cardioversion) creates a transient high-risk period.⁸

Two strategies are accepted for AF of unknown or longer duration:⁸ Strategy 1 — Delayed cardioversion after anticoagulation: Therapeutic anticoagulation for ≥3 weeks before cardioversion, followed by ≥4 weeks post-cardioversion. Most straightforward and does not require imaging.

Strategy 2 — transesophageal echocardiogram (TEE)-guided early cardioversion: Transesophageal echocardiography to exclude LAA thrombus, followed by immediate cardioversion under concurrent anticoagulation (typically therapeutic heparin bridging), then ≥4 weeks post-cardioversion anticoagulation. Enables earlier cardioversion without 3-week delay.

The decision to continue anticoagulation beyond the mandatory 4-week post-cardioversion period depends on the CHA2DS2-VASc score, which estimates annual stroke risk in non-valvular AF. Current guidelines recommend anticoagulation for all men with score ≥2 and women with score ≥3 (i.e., beyond the female sex modifier point alone).

The CHA2DS2-VASc score assigns points as follows: congestive heart failure or LV dysfunction (1 point), hypertension (1 point), age 75 years or older (2 points), diabetes mellitus (1 point), prior stroke or TIA or thromboembolism (2 points), vascular disease including prior MI, peripheral arterial disease, or aortic plaque (1 point), age 65 to 74 years (1 point), and female sex (1 point). The maximum score is 9.

Direct oral anticoagulants (DOACs, apixaban, rivaroxaban, dabigatran, edoxaban) are preferred over warfarin for most patients with non-valvular AF due to superior efficacy-safety profiles across the pivotal trials (RE-LY, ROCKET-AF, ARISTOTLE). Warfarin remains indicated in valvular AF (mechanical prosthetic valves, moderate-severe mitral stenosis) and in patients with severe renal impairment or other DOAC contraindications.⁹