Retrospective Study Shows Ischemic Stroke and Atrial Fibrillation Linked in Time
As published in JAMA Cardiology, data from continuous rhythm monitoring devices showed atrial fibrillation (AF) was directly and transiently associated in time with ischemic strokes.
Among 891 people who had an ischemic stroke during continuous cardiac monitoring, 76.5% had no AF in the 30 days before their stroke. Another 16%, however, had AF at least once in both the 30 days immediately before and days 91 to 120 before their stroke. Informative discordant rhythm patterns were seen in at least 1 of the periods studied in 7.4%. The presence of AF more than tripled the 30-day risk of ischemic stroke, which was highest within 5 days of AF and diminished thereafter. A temporal association was not seen in patients with prescribed oral anticoagulants (OACs).
"Overall, these findings significantly underscore traditional thinking that AF is likely a causal risk factor for ischemic stroke as opposed to just a risk marker," said Daniel Singer, MD, 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. "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 retrospective case-crossover study of 466,635 patient records, a total of 891 patients with continuous rhythm monitoring had an ischemic stroke and 120 days of continuous monitoring prior to the stroke for further evaluation. 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 1 to 30 prior to the index stroke and a control period that included days 91 to 120 prior to the event.
"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 insertable cardiac monitors (ICMs), to detect clinically meaningful AF episodes that may lead to a stroke," said Rob Kowal, MD, PhD, 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."