Dr Tim Gattorna

Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia and is associated with increased morbidity and mortality. There are a high number of undetected cases in the community and therefore an index of suspicion and consideration of the diagnosis with manual palpation of the radial pulse at the time of a consultation should be performed. Confirmation with a twelve lead ECG is required.

Once AF is established the risk of stroke needs to be assessed. This risk is the same regardless of whether the patient has paroxysmal, persistent or permanent AF. The use of validated assessment tools such as the CHA2DS2-VASc: Congestive cardiac failure, Hypertension, Age over 75, Diabetes, Stroke/TIA/thromboembolism, prior Vascular disease, Age 65-74, Sex (female) and HAS-BLED (1) is recommended.

Determine symptoms, clinical history, and AF pattern

A detailed history, including previous therapies, the frequency, duration, severity and precipitants of symptoms, co-morbidities and examination are crucial. Patients with haemodynamic instability, evidence of pre-excitation (Wolff-Parkinson-White syndrome), evidence of myocardial ischemia/infarction or heart failure require urgent transfer to an emergency department.

Some patients’ clinical condition may improve quickly with prompt rate control while others need to have sinus rhythm restored immediately.

Initial diagnostics should include a pathology screen (FBC, EUC, TFT), echocardiography and a twelve lead ECG. Further tests can be guided by the clinical findings.

Rate control

Ventricular rate control can generally be achieved with atrioventricular nodal blocking agents such as B-blockers, calcium antagonists or digoxin (alone or in combination). In patients with mild to moderate symptoms, slowing the rate often results in significant improvement or even resolution of symptoms.

The target ventricular rate depends on the presence or absence of symptoms and underlying cardiac disease. A rate below 85 beats per minute at rest is reasonable in symptomatic patients, which can be titrated dependent on the response. For asymptomatic patients with permanent AF, and no known cardiomyopathy, an initial more lenient rate control goal of <110 beats/min may be reasonable. The best method of assessment of rate control is a 24-hour Holter monitor.

Patient referral is recommended when the treating doctor is no longer comfortable with decision-making, when a rhythm control strategy (anti-arrhythmic medications or catheter ablation) is being considered, for patients with coexistent cardiac disease, difficult to control ventricular rates or ongoing symptoms.

 

Key Points

  • Consider the diagnosis (manual palpation of pulse)
  • Confirm diagnosis with 12 lead ECG
  • Prevention of thromboembolism (CHA2DS2VAsc score)
  • Symptom assessment (thorough history, examination)
  • Optimal management of concomitant cardiovascular disease
  • Rate control
  • Correction of rhythm disturbance (in symptomatic patients)
  • Assess and treat risk factors (e.g. sleep apnoea, obesity, hypertension)

Reference: 1. D. Lane, G. Lip. Circulation, Aug14, 2012, Volume 126, Issue 7. Use of the CHA2DS2-VASc and HAS-BLED Scores to Aid Decision Making for Thromboprophylaxis in Nonvalvular Atrial Fibrillation

 

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