Atrial fibrillation: Diagnosis, management, and recent updates

---

Reference: March 2025 | Issue 3 | Vol 11 | Page 26

---

Atrial fibrillation (AF), the most common arrhythmia clinically encountered, is likely to increase in prevalence as our detection methods continue to improve and our population ages. It is suggested that as many as one-in-three people will develop AF in their lifetime.¹ Therefore, it is essential for physicians in all areas of practice to be able to identify the disorder, and have a general understanding of the morbidity AF can cause, along with knowledge of its basic management.

As per current European Society of Cardiology (ESC) guidelines,² AF is defined as a supraventricular arrhythmia, with uncoordinated activation of the atria, resulting in a loss of atrial contraction effectiveness. On a 12-lead electrocardiogram (ECG), there are no discernible P waves and QRS complexes occur irregularly. There are multiple classifications of AF, beyond the scope of this review, but generally AF can be classified as:

• Paroxysmal AF: AF terminating in less than seven days – spontaneously or with medical intervention.
• Persistent AF: AF for more than seven days or not self-terminating.
• Permanent AF: Determined by both physician and patient, at which no further attempts to restore sinus rhythm are planned.

Diagnosis

AF is classically diagnosed with typical symptoms and a 12-lead ECG. Newer technologies such as implantable loop recorders and other cardiac monitoring have complicated the diagnosis of AF. The duration of time in AF on these long-term monitoring devices and its clinical relevance with regards to anticoagulation for stroke prevention is an area of debate.

All patients with newly diagnosed AF should have a 12-lead ECG, symptom assessment, and blood tests inclusive of full blood count, thyroid function tests, haemoglobin A1c, and renal function tests. Transthoracic echocardiography should be utilised in most patients to elucidate a substrate for AF and to identify cardiac consequences of AF such as left ventricular ejection fraction (LVEF) reduction.

Select patients with AF may also require more specialised lab testing including NT-proBNP and troponin testing. Holter monitoring to evaluate rates in the community and overall AF burden can be helpful. Coronary artery imaging in the form of CT coronary angiogram and coronary angiography may be considered to aid treatment strategies for those in whom ischaemia is suspected. Transoesophageal echocardiogram (TOE) and cardiac MRI can help to assess for valvular disease and cardiomyopathies, which may be the aetiology of AF or the consequence of AF.

Symptomatology

While symptoms do not predict morbidity and mortality, they do impact quality of life. Symptoms can range from palpitations and fatigue to chest pain, syncope, and dizziness. The modified European Heart Rhythm Association symptom classification helps physicians to classify each patient’s degree of symptoms and can be used at intervals to assess response to therapy.

Management

Risk factor management
Treating risk factors for AF is often underappreciated, but nevertheless essential. Blood pressure-lowering therapies will both reduce the likelihood of AF recurrence and progression as well as prevention of adverse cardiovascular events. A target weight loss of 10 per cent in obese and overweight individuals is recommended. Regular tailored exercise is also recommended by the ESC to improve cardiorespiratory fitness.

Alcohol consumption, a well identified trigger and risk factor for AF progression, should be reduced to less than three standard drinks per week. Glycaemic control in patients who have diabetes mellitus is strongly recommended. Patients who have heart failure (HF) in association with AF should be decongested and started on appropriate LV remodelling agents. The more novel sodium-glucose co-transporter 2 inhibitor (SGLT2i) medicines are now recommended in our HF cohort regardless of LVEF.

Ischaemic stroke and thromboembolism prevention
All patients with AF should be considered for anticoagulation to reduce the risk of stroke. Traditionally it has been postulated that thromboembolism in AF is caused by static blood in the left atrial appendage (LAA) in a fibrillating atrium predisposing to thrombus formation. However, it is likely more complex.³ An abnormal atrial tissue substrate due to age and vascular risk factors is most likely another key factor. As AF progresses, the atrium becomes structurally remodelled and increases the risk of thromboembolism further.

Patients with AF should have a CHA2DS2VA score calculated (Table 1) which has been updated from the previous system, with the sex category being removed from stroke risk calculation.

Oral anticoagulation (OAC) is recommended in patients with a CHA2DS2VA score of two or more. In patients with hypertrophic cardiomyopathy or cardiac amyloid and accompanying AF, OAC is recommended regardless of CHA2DS2VA score. Regular reassessment of this score in patients with AF should be carried out in primary practice and cardiology outpatient departments.

Patients with a CHA2DS2VA score of one should be considered for OAC. It is important to note that antiplatelet therapy is not recommended as an alternative to OAC for stroke prevention and the addition of an antiplatelet to OAC for preventing stroke is not recommended. Consideration and management of a patient’s bleeding risk factors is essential when assessing a patient eligible for OAC.

Direct OACs, such as apixaban, edoxaban, and rivaroxaban, are preferred over vitamin K antagonists (VKAs), ie, warfarin, except in patients with mechanical heart valves or moderate to severe mitral stenosis. When VKA is to be prescribed, a target INR (international normalised ratio) of 2.0-3.0 is recommended; however, this may not be sufficient in mechanical mitral valve replacement. Patients over 75 who are on long-term VKA and stable therapeutically may be maintained on warfarin.

Patients undergoing cardiac surgery often have additional surgical closure of the LAA to prevent ischaemic stroke and thromboembolism. A more recent advance is the use of a percutaneous LAA occlusion device which can be considered in patients with contraindications to long-term OAC such as undifferentiated major bleeding or intracranial bleeding. This device is deployed into the LAA endoscopically in a cardiology catheterisation laboratory.

Rate control
When a patient presents to the emergency department in AF with rapid ventricular response, a lenient target heart rate of <110 beats per minute is recommended initially, with the goal of minimising symptoms and preventing tachycardia-mediated cardiomyopathy.

The first-line drug tends to be beta-blockers. Diltiazem and verapamil may be considered provided LVEF is greater than 40 per cent.  In patients with altered haemodynamics or a severely reduced EF, intravenous amiodarone, digoxin, or esmolol can be considered. Over time, if these pharmacotherapies fail, or if patients have contraindications to these drugs, with ongoing symptoms of AF, AV nodal ablation and pacemaker insertion may be required.

Rhythm control
Rhythm control is the goal of returning a patient to sinus rhythm or reducing the burden of AF, which includes lower activity levels, greater risk of thromboembolic events and cognitive decline, and increased hospitalisation, morbidity, and mortality in HF patients. Electrical cardioversion, pharmacological approaches, and catheter ablation may be utilised.

Electrical cardioversion: While patients who are unstable may require emergency electrical therapy in the form of synchronised cardioversion, this is also done on an elective basis in stable patients. For scheduled cardioversion, ESC guidelines suggest at least three weeks of uninterrupted anticoagulation prior to the procedure, and at least four weeks after procedure, regardless of its success in restoring sinus rhythm due to the peri-procedural stroke risk secondary to atrial stunning. In particular, symptomatic patients in whom restoring sinus rhythm is necessary sooner, TOE can help assess for cardiac thrombus prior to cardioversion.

Pharmacological approaches: There are multiple pharmacological options for rhythm control, however, these drugs carry precautions and contraindications. In a patient without coronary artery disease (CAD) or severely reduced EF, flecainide may be considered, particularly in younger patients, and prescribing may be best positioned with a specialist. This can be used as a pill in the pocket therapy for paroxysms of AF or be taken regularly to reduce AF burden in the outpatient setting.

Caution is required in patients with underlying conduction disease, and it should not be used for conversion of atrial flutter. On this point, beta-blockers should be considered concomitant with flecainide so as to prevent 1:1 conduction if rhythm changed to atrial flutter, which can result in life-threatening rapid ventricular response.

Other antiarrhythmics routinely used in the cardiology outpatient department include amiodarone and dronedarone. Amiodarone is a useful drug in the acute setting when patients with AF have underlying HF with reduced EF (HFrEF) or CAD. It can be given as an infusion, which may restore sinus rhythm without requiring sedation and electrical cardioversion. However, there may be contraindications to this such as conduction disease and prolonged QTc.

Amiodarone’s toxicity is well documented, and long-term use in the outpatient setting needs to be closely monitored. It is best used to facilitate restoration/maintenance of sinus rhythm while awaiting definitive therapy such as catheter ablation, rather than long-term in isolation. The potential for thyrotoxicity, liver toxicity, and photosensitivity need to be highlighted to patients who are prescribed the drug.

Dronedarone, from the same antiarrhythmic class as amiodarone, was shown in the ATHENA trial in 2009 to reduce the risk of hospitalisation and death in patients with paroxysmal or persistent AF.⁵ Of note, the dronedarone arm of this trial had higher incidence of bradycardia, QT prolongation, gastrointestinal side-effects, and rises in creatinine levels. It should be avoided in patients with HF.

The EAST-AFNET 4 study shed light on the importance of early rhythm control in patients with AF, showing a lower risk of adverse cardiac outcomes in this strategy compared with usual care.⁶ Implementation of a rhythm control strategy is recommended within 12 months of diagnosis in select AF patients to reduce risk of cardiovascular death or hospitalisation, irrespective of symptoms. This reflects a significant change in care for patients, but may be best applied in younger patients.

Catheter ablation: Catheter ablation for AF is now an option in most Irish tertiary centres. This endoscopic approach involves femoral venous access, crossing the intra-atrial septum to the left atrium, and ablation of the pulmonary veins, which are the common substrate for AF.

This procedure carries a 2 per cent risk of major complication, and therefore demands pre-procedural shared decision-making between patient and cardiologist. In patients with an elevated body mass index, weight loss of 3 per cent or more of body weight prior to ablation is associated with greater benefits and freedom from AF post ablation.⁷

Current guidelines state that catheter ablation is recommended in patients with AF in whom antiarrhythmic drug therapy has failed. It is recommended as a first-line option in paroxysmal AF to reduce symptoms and progression of AF. It can be considered as a first-line option in persistent AF.

Often patients may require further ablation procedures if AF recurs after successful ablation or persists after failed ablation. It will not cure AF, but may reduce the burden for the appropriately selected patients, with procedural success rates around 75-80 per cent in paroxysmal AF.

In patients with HfrEF and a risk of tachycardia-induced cardiomyopathy, ablation is recommended. Indeed, a landmark randomised control trial, CABANA, demonstrated that patients with AF and longstanding HF had an improved survival and quality of life when undergoing catheter ablation compared with drug therapy.⁸ Additionally, patients with AF-related bradycardia and sinus pauses after AF termination may require consideration of AF ablation to prevent permanent pacemaker requirements.

There are multiple technologies used for catheter ablation including cryoablation, radiofrequency, and most recently, pulse field ablation (PFA). PFA results in programmed cell death and appears to have an improved safety profile with apparent reduction in atrio-oesophageal fistulas compared to cryo/radiofrequency ablation, with similar efficacy.

Conclusion

This short review highlights general approaches to the management of AF in Ireland. Adjustments to the CHA2DS2VA scoring system have recently been introduced which impact our decision-making around OAC. New evidence on the importance of rhythm control has prompted a paradigm shift in cardiology outpatient departments.

Novel and noteworthy key points

1. A rhythm control strategy should be adopted irrespective of symptoms in younger patients with a diagnosis of AF within the last 12 months.
2. PFA is a newer technology used to perform catheter ablation for AF and appears to have similar efficacy to other ablation technologies with possible improved safety.
3. The burden of AF is an important factor that will dictate the efficacy of a rhythm control strategy.
4. CHA2DS2VA score no longer includes gender as a risk factor for stroke.
5. Weight loss prior to ablation improves outcomes including freedom from AF.