Atrial CMR in Patients With CVA of Unknown Source and no Known AF
Atrial CMR in Patients With CVA of Unknown Source and no Known AF
This research study will investigate a new method for identifying which patients should be
 offered blood thinners or therapies to reverse the underlying causes after stroke.

 Atrial fibrillation(AF) is the primary risk factor for ischaemic stroke, increasing the risk
 by up to 5-fold. In AF, the upper heart chambers don't pump blood effectively into the lower
 chambers. When this happens, a blood clot can form, dislodge and leave the heart blocking an
 artery in the brain and cause a stroke. However, AF is often an intermittent condition and
 therefore difficult to diagnose. As such, there are a group of patients in whom no cause of
 their stroke can be identified.

 In this study, we will recruit 92 patients from Guy's and St Thomas' Hospital, Princess Royal
 University Hospital and King's College London.

 As part of routine clinical care, patients undergo insertion of an Implantable Loop Recorder
 (CE Marked device), a minimally invasive procedure that allows accurate beat-to-beat
 monitoring to identify patients who develop intermittent AF post-stroke. We will request
 access to the data collected from this device and perform atrial MRI imaging in these
 patients to compare the findings between patients that do and do not have AF. If we show that
 atrial MRI scans are significantly different between patients with and without AF, we will
 use this information to support a trial of starting appropriate therapies (e.g. blood
 thinners) in these patients on the basis of MRI findings. This approach would have the
 advantage of enabling therapies to be offered to the right patients earlier and prevent
 repeat, potentially disabling stroke.
Inclusion Criteria:

 Patients will be recruited within 3 months of an acute ischaemic stroke. It must also be
 feasible to perform a cardiac MRI on all patients enrolled within 3 months of the acute
 ischaemic stroke.

 Inclusion criteria includes patients with:

 -  Patient consent or advice given by consultee can be obtained

 -  Confirmed acute ischaemic stroke with evidence on brain CT and/or MRI within 3 months
 of study enrolment • Ischaemic stroke of unknown source Expected survival >12 months.

 -  At least one additional stroke risk factor (i.e. CHA2DS2VASc>=3)

 -  Sinus rhythm on 12 lead ECG, telemetry and a regular pulse on clinical examination

 -  Above 18 years of age

 Exclusion Criteria:

 -  Unable to obtain patient consent or advice by consultee

 -  History of atrial fibrillation

 -  Atrial fibrillation detected on ECG and/or telemetry (AF duration of at least 30
 seconds required for diagnosis)

 -  eGFR <30ml/min

 -  Indication for pacemaker/implantable cardioverter-defibrillator

 -  Contra-indication to undergo cardiac MRI (e.g. severe claustrophobia, unable to lie
 flat for prolonged period, contrast allergy)

 -  Carotid stenosis >50% on Duplex ultrasound associated with anterior circulation
 infarction

 -  Vertebrobasilar stenosis >50% on CT/MR angiography associated with posterior
 circulation infarction

 -  Single, isolated lacunar stroke with a corresponding lacunar infarct on brain CT/MRI

 -  Specific aetiology for cause of stroke (e.g. arteritis, dissection, drug abuse)