Choosing antiarrhythmic drugs for atrial fibrillation

Atrial fibrillation (AF) is a heterogeneous arrhythmia, so rhythm-control prescribing cannot rely on a single preferred medicine. The appropriate antiarrhythmic drug depends on symptoms, AF pattern, left ventricular function, coronary disease, ventricular hypertrophy, renal function, age, comorbidities, and the likelihood that treatment will be maintained safely over time.

Pharmacologic rhythm control in atrial fibrillation includes medicine used for cardioversion, prevention of recurrent AF, or both. The aim may be relief of palpitations and fatigue, improved exercise tolerance, reduced hospital presentations, or preservation of ventricular function in patients with a high burden of AF. Rhythm control does not remove the need to assess stroke risk or prescribe anticoagulation when indicated.

For Australian clinicians, prescribing also reflects local access and follow-up. A patient in metropolitan Sydney or Melbourne may have rapid access to an electrophysiologist and serial ECGs, while a person in regional Queensland, Western Australia, or the Northern Territory may need shared monitoring between primary care, a local hospital, and a tertiary service. Therapeutic choice must therefore combine electrophysiology with practical safety planning.

Establish the clinical setting before choosing a drug

The first decision is whether rhythm control is clinically worthwhile and feasible. Symptomatic paroxysmal AF, persistent AF causing functional limitation, tachycardia-mediated cardiomyopathy, or recurrent presentations may justify an attempt to maintain sinus rhythm. Earlier rhythm control can be particularly relevant when AF is newly diagnosed, although treatment still needs to be individualised according to comorbidity and patient preference.

A baseline assessment should include a 12-lead ECG, transthoracic echocardiography, electrolytes, renal and hepatic function, thyroid status, medication review, and evaluation for sleep apnoea, alcohol excess, hypertension, obesity, and ischaemia. The ECG may reveal conduction disease, prolonged QT, ventricular pre-excitation, or a broad QRS that changes the safety profile of a proposed drug. AF duration and anticoagulation status are essential when planning pharmacological cardioversion.

Stroke prevention remains a separate pathway. Restoration of sinus rhythm does not immediately eliminate thromboembolic risk, and anticoagulation decisions should follow the patient’s validated risk profile and the circumstances of cardioversion. In Australia, clinicians also need to check current Therapeutic Goods Administration information and Pharmaceutical Benefits Scheme arrangements, as registration, subsidy, and prescribing restrictions can influence access.

Class IC drugs suit carefully selected hearts

Flecainide and propafenone are effective options for many patients with paroxysmal AF who have no substantial structural heart disease. They can reduce symptomatic recurrences and may be used as regular maintenance therapy. In selected patients, a supervised “pill-in-the-pocket” strategy can provide rapid self-treatment of an episode, but the first dose should generally be assessed in a monitored setting after appropriate screening.

Class IC agents should be avoided or used with great caution in patients with prior myocardial infarction, significant coronary artery disease, left ventricular systolic dysfunction, important ventricular hypertrophy, or substantial conduction disease. Exercise testing may help identify rate-related QRS widening in some patients, particularly when there is uncertainty about underlying ischaemia or conduction reserve. Renal and hepatic function also influence exposure and follow-up requirements.

An atrioventricular nodal blocker is commonly paired with flecainide or propafenone to reduce the risk of rapid atrial flutter conduction. This must be balanced against bradycardia, hypotension, and conduction-system disease. Drug interactions matter: propafenone has beta-blocking properties and can interact with medicines metabolised through hepatic pathways, while flecainide requires attention to renal clearance and QRS duration.

Heart failure and coronary disease narrow the options

Patients with heart failure with reduced ejection fraction require particular caution. Many antiarrhythmic agents can worsen ventricular function or provoke proarrhythmia, and the selected treatment should fit guideline-directed heart failure therapy. Amiodarone is often considered when significant structural disease limits alternatives, although its extracardiac toxicity makes it a poor default choice for long-term treatment when safer options are available.

Coronary disease also changes the balance between efficacy and harm. A history of infarction or active ischaemia generally argues against class IC therapy. Before prescribing, clinicians should distinguish stable coronary disease from the absence of meaningful structural disease, rather than treating all cardiovascular risk factors as equivalent contraindications. Echocardiographic findings, symptoms, exercise capacity, and previous investigations should be integrated.

Implantable devices can provide protection or pacing support in selected patients, but they do not make every antiarrhythmic drug safe. Bradyarrhythmia, inappropriate shocks, and drug-related changes in defibrillation or pacing thresholds still require surveillance. Decisions about device configuration should remain aligned with the patient’s indication; a review of ICD selection evidence can help frame the relationship between device strategy and rhythm management.

Compare sotalol, dronedarone, and amiodarone carefully

Sotalol combines beta-blocking activity with class III antiarrhythmic effects. It may be useful for recurrent AF in carefully selected patients, but QT prolongation and torsades de pointes are important risks. Renal function must be checked because sotalol is substantially renally cleared, and dose selection should account for bradycardia, electrolyte disturbance, female sex, age, and concomitant QT-prolonging medicines. Initiation or dose escalation may require monitored ECG assessment according to local protocol.

Dronedarone has a more limited role. It may be considered in selected patients with paroxysmal or persistent AF who are in sinus rhythm or undergoing rhythm management, but it is unsuitable in certain forms of heart failure and in permanent AF. Hepatic injury, interactions, bradycardia, and effects on renal laboratory results should be considered. Its place in practice may also be affected by Australian availability and subsidy arrangements, which should be checked rather than assumed.

Amiodarone is highly effective for maintaining sinus rhythm across a broad range of structural heart disease. Its limitations are cumulative pulmonary, thyroid, hepatic, ocular, neurological, dermatological, and cardiac toxicity, along with numerous drug interactions. Before and during therapy, monitoring should be purposeful and documented, including thyroid and liver tests, ECG assessment, medication reconciliation, and evaluation of new respiratory or visual symptoms. The lowest effective duration and dose are desirable.

Make initiation and monitoring part of the prescription

An antiarrhythmic prescription should specify how treatment starts, what ECG changes are acceptable, which symptoms require urgent assessment, and when follow-up occurs. Baseline potassium and magnesium should be corrected, renal dosing should be explicit, and the patient should receive a clear list of medicines to avoid or discuss before starting. This is especially important for people using antibiotics, antidepressants, antipsychotics, or over-the-counter products that may affect QT interval or drug metabolism.

Monitoring needs to match the medicine. Flecainide and propafenone require attention to QRS widening, conduction slowing, and exercise-related effects. Sotalol requires QT and renal surveillance. Amiodarone requires structured thyroid, hepatic, pulmonary, and ocular review. Dronedarone requires attention to rhythm status, liver function, heart failure symptoms, and interactions. A symptom diary or wearable rhythm record can support assessment, but consumer-device data should not replace a diagnostic ECG when treatment decisions carry proarrhythmic risk.

Australian practice often involves coordination across general practice, cardiology, pharmacy, and hospital services. A patient travelling long distances from rural New South Wales or South Australia may need pathology and ECG arrangements close to home, with results reviewed by a specialist team. Medication affordability, PBS authority requirements, transport, health literacy, and access to a pharmacist can influence adherence as much as pharmacology does.

Reassess recurrence, adverse effects, and alternatives

Recurrence of AF does not automatically mean that a drug has failed completely. The clinician should assess adherence, alcohol exposure, sleep apnoea, blood pressure, weight, thyroid disease, renal change, interacting medicines, and the duration and burden of episodes. A partially effective drug may still reduce symptoms, but recurrent cardioversion, emergency presentations, or progressive ventricular dysfunction may favour a different strategy.

Catheter ablation is an important alternative for symptomatic paroxysmal or persistent AF, particularly when antiarrhythmic drugs are ineffective, poorly tolerated, or inconsistent with the patient’s goals. Pulsed-field ablation is developing rapidly, and evidence about recurrence and repeat procedures continues to evolve; clinicians can review predictors after pulsed-field ablation when discussing expectations after an initial procedure.

Drug therapy and ablation should not be treated as isolated choices. Short-term antiarrhythmic treatment may support rhythm stabilisation after ablation, while some patients prefer medication to an invasive procedure after a transparent discussion of benefits and risks. In every pathway, anticoagulation, risk-factor management, symptom assessment, and follow-up remain central.

Selecting an antiarrhythmic drug is a process of matching electrophysiological benefit with the patient’s substrate, comorbidities, monitoring capacity, and treatment priorities. Clinicians, researchers, and trainees can engage with the Journal of Arrhythmia’s clinical and research resources, and can contact the journal to discuss relevant submissions, educational material, or emerging evidence in AF pharmacotherapy.