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Atrial fibrillation occurring initially during acute medical illness: the heterogeneous nature of disease, outcomes and management strategies.

Atrial fibrillation (AF) occurring transiently in association with other acute medical conditions, such as surgery, infectious diseases and myocardial infarction, has provoked substantial debates. This com-mon arrhythmia is often seen in the emergency department, intensive care unit (ICU) and others, and has been termed as ‘secondary’, ‘acute’, ‘transient’, ‘resolved’ or ‘new-onset’ AF, all of which suggests or implies that the arrhythmia is caused by a reversible aetiology and being self-limited. 1,2 However, ‘transient’ AF may not be conclusive as AF often re-occurs during follow-up or may be merely the first de-tection of paroxysmal or persistent AF. Indeed, the episode of ‘transient’ AF in association with other acute medical conditions may indicate that the individual is predis-posed to developing AF. Otherwise the patient may well have had si-lent episodes of AF but was unaware, and the acute medical presentation may be a result of decompensation related to the arrhythmia or represent as a resultant complication. Perhaps more relevant is whether such ‘transient’