Wearable Device May Best Holter in AF Detection After Stroke  

Sue Hughes            

June 06, 2017

PRAGUE, Czech Republic — A new wireless patch device that enables prolonged monitoring for atrial fibrillation (AF) after cryptogenic stroke identified more patients with AF than does standard 24-hour Holter monitoring, a new study shows.

Results of the Early Prolonged Ambulatory Cardiac monitoring in Stroke (EPACS) study were presented by James Teo, MD, Kings College Hospital, London, United Kingdom, at the 3rd European Stroke Organisation Conference (ESOC) 2017.

"The convenience of the patch-based cardiac monitor substantially increased the uptake and efficiency of cardiac monitoring early after ischemic strokes and TIA [transient ischemic attack] and may have superior AF detection rate to standard approaches," he concluded.

Dr Teo explained that paroxysmal AF is a frequent preventable cause of ischemic stroke, but its transient nature means that 24-hour recordings miss a substantial proportion of patients.

He added that recent clinical trials (EMBRACE and CRYSTAL-AF) of long-duration recordings using implantable loop recorders indicate that there is substantially more AF to be detected, but the best means to perform this monitoring in patients after cryptogenic stroke is unknown.

Systems for longer-term recording have important limitations: Event-triggered loop recorders are cumbersome, while implanted loop recorders require a minor surgical procedure. There is a need for patient-friendly long-duration cardiac monitoring systems for stroke patients, Dr Teo noted.

The current study evaluated a wearable waterproof adhesive cardiac monitoring patch (Zio Patch, iRhythm Technologies Inc).

For the study, 116 patients within 3 days of a cryptogenic stroke from two UK centers were randomly assigned to outpatient Holter monitoring for 24 hours  (standard practice; n = 60) or to standard Holter 24-hour monitoring plus the new patch-based monitoring system (n = 56).

Dr Teo told Medscape Medical News that the patch is applied to the chest while the patient is still in hospital and is worn for 14 days. After 14 days, the patient is asked to return the patch device by mail so that the data can be assessed. Participants in both groups attended a follow-up appointment at 90 days to find out how many had developed AF and how many had had another stroke or TIA.

Results showed that 43 patients in the patch group and 47 patients in the standard practice group completed the study.  

AF was detected in 7 of 43 patients in the patch group (16.3%) compared with  just 1 of 47 patients in the standard Holter group (2.1%), for an odds ratio of 8.9 (95% confidence interval, 1.1 - 6.0; P = .047).

The secondary analysis comparing AF in the same patients with the two techniques showed the same results: 7 patients with AF detection in the patch group vs 1 in the Holter monitoring group (2.1%).

Stroke rates did not differ between the two groups at 90 days: 2.1% in the control group versus 2.3% in the patch group.  

"We had quite a high drop-out rate — about 20% — but this was due to problems with the standard Holter monitoring, which was included in both arms," Dr Teo commented. "The Holter sometimes comes off and patients don't put it back, they find it cumbersome to wear, and they often don't return to the hospital to have it taken off. This approach need two journeys to the hospital on consecutive days, which can be a problem for many."

The patch is easier in several ways, he added. "It is much easier to wear and does not require a second hospital appointment as the patient returns it by post.

"The patch was successfully worn and returned after the 14 days by all patients except one in whom we had difficulty using the patch because of excess adiposity in the chest."

This patch is in clinical use in the United States. In the United Kingdom, it is approved but negotiations are still underway with the National Institute for Health and Care Excellence over pricing. Dr Teo said it is being used in the private UK system but generally is used more by cardiologists for investigating syncope.

"We know that the longer we monitor patients the more AF we pick up, but we need to find the optimal way of doing this," he added. "I believe a patch based system is the future. There are several similar patches becoming available now, but we have to work out how best to use them. The first models, such as the one used in this study, are limited to a couple of weeks of monitoring as the battery has limited lifespan and is not rechargeable. They are also single use at present and have a significant cost of several hundred pounds."

Other alternatives are also being investigated, such as implantable loop recorders, which can record for a year or more, but these involve a surgical procedure and again are much more expensive than the patch. The patch is seen as an intermediate between 24-hour Holter monitoring and 1-year implanted recorder.

Stroke experts at ESOC seemed encouraged by the study.

Jesse Dawson, MD, University of Glasgow, United Kingdom, said, "This is a really exciting study. We know we need to do more to detect AF in our stroke patients, and this is a clinician- and patient-friendly approach that seems to reliably detect cases of AF."

Bart van der Worp, University Medical Center, Utrecht, the Netherlands, and president-elect of the European Stroke Organisation, commented: "This is cconfirmation that we should monitor for AF for longer than 24 hours after cryptogenic stroke or TIA. This patch system does seem very easy to use. At present, most TIA patients only get an ECG [electrocardiogram], and stroke patients are usually monitored for 24 hours.  But we know this is not sufficient.  The question is, If we find AF 1 month later, is it related to stroke? I personally think it is quite likely."

Alastair Webb, MD, University of Oxford, United Kingdom, added:  "This is a nice idea — an easy way of monitoring AF longer term. The patch has potential, and if they can demonstrate they pick up clinically relevant AF that has an impact on treatment and outcome, then it would obviously be very useful. But this study was relatively small."

Dr Webb also brought up the issue of what to do about AF detected further out from a stroke. "The problem is that if we detect a prolonged period of AF within 7 days, then we know that is a good marker of risk and the patient should be anticoagulated, but if we detect AF further out we don't really know how much AF constitutes a risk of a further stroke and whether patents should be treated. We don't necessarily know what to do with the information. If we see regular AF, they should definitely be treated. But if we catch one period of AF in 3 months, we are not sure what to do about that."

This trial was investigator initiated and supported by a grant for the treatment and detection of AF from Bristol-Myers Squibb (BMS). Dr Teo receives grant funding from BMS.

3rd European Stroke Organisation Conference (ESOC) 2017. Session P24. Presented May 18, 2017.

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