Cardiac investigations in acute ischaemic stroke

Editor – I read with interest the retrospective study from Bahl et al highlighting cardiac aetiologies (up to 24%) in an unselected young population with acute ischaemic stroke (n=167).¹

Atrial fibrillation (AF) is responsible for up to one-third of acute ischaemic strokes and may be the index presentation of AF.² With an established efficacy of oral anticoagulation in the prevention of stroke associated with thromboembolic events and AF, thorough cardiac investigations are warranted to reduce morbidity and mortality, particularly in a young patent population.

Bahl et al investigated patients for AF with ambulatory electrocardiography (ECG) monitoring and a mean duration of 68.4 hours (2.9 days), however detection of AF was low (1.8%; 2/109). The authors acknowledged the need for prolonged ambulatory monitoring and the AF-SCREEN collaboration has endorsed handheld patient activated ECG devices as a preferred screening tool.³ The National Institute for Health and Care Excellence (NICE) has appraised similar technology (AliveCor®), reported to be cost-effective and have both a high sensitivity and specificity in the detection and interpretation of AF.⁴ Furthermore, EMBRACE demonstrated that AF lasting 30 seconds was detected in 16.1% of cryptogenic stroke patients with use of a 30-day event triggered recorder compared with 3.2% with a 24-hour monitor, and this led to anticoagulation in nearly double the number of patients in the intervention group.⁵

Interestingly, 9% (15/167) of patients had an intracardiac source of embolus (‘heart failure and thrombus’ and ‘valvular heart disease’) and 25.1% (42/167) of patients had no underlying cause. Despite this, only 4.2% (7/167) of patients had transoesophageal echocardiography (TOE). A thrombus located in the left atrium or, more precisely, the left atrial appendage (LAA) is the most prevalent source of intracardiac emboli and is typically associated with AF. TOE is the imaging modality of choice for the evaluation of LAA.^6,7 Furthermore, in the absence of diagnosed AF, left atrial or LAA abnormalities may be a compelling indication for prolonged ECG monitoring.

In summary, investigation for aetiology of stroke in young patients should involve scrupulous cardiac investigations identifying those patients who would benefit from prolonged ambulatory ECG monitoring and increased utilisation of TOE.