Study highlights temporal relationship between AF and stroke


Medtronic has announced the publication of a study demonstrating, through the use of a continuous rhythm monitoring device, that atrial fibrillation (AF) is directly and transiently associated with ischaemic stroke. The findings were published online in JAMA Cardiology.

This retrospective case-crossover study leveraged data from 466,635 patients included in both the Optum deidentified electronic health record (EHR) and the Medtronic CareLink network databases.

Of those, a total of 891 patients with Medtronic cardiovascular implantable electronic devices (CIEDs) capable of continuous rhythm monitoring sustained both an ischaemic stroke and received 120 days of continuous monitoring prior to their stroke.

A threshold of AF exposure was defined as AF lasting 5.5 hours or more on any given day. Patients were evaluated during a case period that included days one to 30 prior to the index stroke and a control period that included days 91 to 120 prior to the event. It was found that 76.5% (682/891) subjects had no AF meeting the threshold in either 30-day period, 16% (143/891) had at least one day with 5.5 hours or more of AF in both periods, and 7.4% (66/891) had informative, discordant rhythm patterns (defined as those that had AF exceeding 5.5 hours in only one period).

“Overall, these findings significantly underscore traditional thinking that AF is likely a causal risk factor for ischaemic stroke as opposed to just a risk marker,” said Daniel Singer, professor of medicine at Harvard Medical School, professor in the Department of Epidemiology at the Harvard TH Chan School of Public Health, and Division of General Internal Medicine at Massachusetts General Hospital, Boston, USA. “The results indicate that prolonged episodes of AF increase stroke risk, but this risk decreases rapidly following the end of the episode. These findings raise the possibility that time-limited anticoagulation for infrequent episodes of AF may be an effective stroke prevention strategy.”

In this study, subjects evaluated had Medtronic CIEDs capable of continuous heart rhythm monitoring via the Medtronic CareLink network, including 114 patients with Medtronic insertable cardiac monitors (ICMs) and 777 with various Medtronic transvenous devices with atrial leads, including implantable cardioverter defibrillators (ICDs), cardiac resynchronisation therapy (CRT) devices, and pacemakers.

“As of late, there has been significant discussion surrounding the temporal relationship of AF episodes to stroke, as well as the use of continuous cardiac monitoring, specifically with ICMs, to detect clinically meaningful AF episodes that may lead to a stroke,” said Rob Kowal, chief medical officer of the Cardiovascular Diagnostics and Services business, which is part of the Cardiovascular Portfolio at Medtronic. “This evidence highlights that patients are at highest risk for a stroke within five days of an AF episode that lasts five and a half hours or more. In addition to supporting the use of OACs in this patient population, this study also suggests the value of long-term cardiac monitoring to accurately detect these critical AF episodes.”


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