Silent atrial fibrillation (AF)

Silent atrial fibrillation (AF)

Silent atrial fibrillation is asymptomatic atrial fibrillation detected by monitoring with telemetry, Holter or implantable recorders. Atrial fibrillation can often be missed if it is paroxysmal. Even short period of electrocardiographic monitoring as occurs in patients with acute myocardial infarction, has shown that silent AF is three times more common than symptomatic AF.¹

In hospital mortality and heart failure are higher in those with silent AF compared to those without atrial fibrillation. Morbidity and mortality rates in those with silent AF are similar to those with symptomatic AF. Even those with silent AF need anticoagulation as per protocol like those with symptomatic AF.

Silent AF is common in heart failure situations and may account for many of the strokes that occur in this condition. Silent AF can possibly be detected by routine screening for AF.² Screening can be done by 24 hour Holter or even sometimes by an implantable loop recorder, though much more expensive and partly invasive modality. Of course, screening with implantable loop recorders will give a much higher yield than 24-72 hour Holter because the former monitors for two years or more if needed.

Screening would be recommended for all with cryptogenic strokes. Once silent AF is detected, further evaluation with transthoracic echocardiogram and thyroid function tests are done in most cases. A repeat Holter evaluation is sometimes done after initiating treatment to assess adequacy ventricular rate control.

References

1. Karim Stamboul, Marianne Zeller, Laurent Fauchier, Aurélie Gudjoncik, Philippe Buffet, Fabien Garnier, Charles Guenancia, Luc Lorgis, Jean Claude Beer, Claude Touzery, Yves Cottin. Incidence and prognostic significance of silent atrial fibrillation in acute myocardial infarction. Int J Cardiol. 2014;174:611–617.
2. Nicole Lowres, Lis Neubeck, Julie Redfern, S Ben Freedman. Screening to identify unknown atrial fibrillation: a systematic review. Thromb Haemost. 2013;110:213–222.