The latest national clinical guideline for stroke

Editor – There is lack of clarity in the latest National clinical guideline for stroke on cardiac monitoring if a cardio-embolic stroke is suspected.¹

It is estimated that between 25 and 60% of atrial fibrillations are paroxysmal (PAF) and approximately one third of the patients affected are asymptomatic.

Thirty percent of all strokes remain without an identifiable cause even after extensive workup. Occult PAF seems to be one of the culprits of ‘cryptogenic’ strokes.

All ischaemic stroke patients should have a standard 12-lead electrocardiogram (ECG), which will detect a new PAF in 2–4% of patients.

Cardiac telemetry for 28–72 hours after index hospital admission has been reported to detect new AF in up to 2.4–18.5% of patients with acute ischemic stroke.² This facility, however, is often used to monitor patients receiving systemic thrombolysis.

Serial ECG assessments within the first 72 hours of an acute stroke significantly improve detection of AF. This strategy is particularly useful when cardiac telemetry is not readily available.³

Given the asymptomatic nature of PAF, patient-activated cardiac monitoring devices are of low clinical value.

Most patients in the UK will receive a single 24/48/72-hour Holter monitor after a cryptogenic stroke as per the current guideline (Fig 1). The diagnosis of PAF is often missed because of low rates of arrhythmia detection by these devices.⁴ These patients will thus miss out on anticoagulation, leading to recurrent strokes and a higher mortality.

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Fig 1.

A flowchart of the step-wise detection of PAF in suspected cardio-embolic stroke patients. AF = atrial fibrillation; ECG = electrocardiogram; PAF = paroxysmal atrial fibrillation; STAF = Score for the Targeting of Atrila Fibrillation

A 7-day ambulatory ECG monitor detects AF in 5.7% of patients with a normal standard ECG and 24-hour Holter. ⁵ In our trust, 7-day ambulatory ECG monitors are used instead of 24/48/72-hour Holter to detect occult PAF.

The EMBRACE (Event Monitor Belt for Recording Atrial Fibrillation after a Cerebral Ischemic Event) study demonstrated that the 30-day event-triggered recorder was significantly more effective than 24-hour Holter for identification of AF in patients with recent cryptogenic strokes. My practice is to perform a 32-day ambulatory ECG monitoring if the 7-day ECG does not detect low-burden PAF.

Surface ECG recorders (7- or 32-day ECG monitor) rely on skin contact electrodes. Skin irritation or ‘allergic’ reactions have been the commonest cause of non-compliance in my practice. This makes it difficult for patients to wear these devices for long durations.

AF detection rate in the CRYSTAL AF (Cryptogenic Stroke and Underlying AF) study were 8.9% at 6 months, 12.4% at 12 months and 30% at 3 years in those with cryptogenic stroke. In view of this evidence, I refer patients in whom prolonged ECG monitoring has failed to detect PAF, have developed allergic reactions to skin contact electrodes or do not wish to wear devices for 32 days to a cardiology colleague for an insertable loop recorder.

Finally, dual-chamber pacemakers and implantable cardioverter defibrillators are cardiac implantable electronic devices. These in situ intra-cardiac devices can be programmed for continuous ECG monitoring in patients with suspected cardio-embolic stroke to detect asymptomatic atrial tachyarrhythmia.

Conflicts of interest

The author has no conflict of interest to declare.