Stroke risk rises transiently with AF episodes in patients with implanted cardiac devices

Reuters Health - 04/10/2021 - In patients with cardiac implantable electronic devices (CIEDs), multihour episodes of atrial fibrillation (AF) were associated with a transient increase in stroke risk in an observational study.

The findings support studies of time-limited anticoagulation for such patients, the researchers say.

The current results are consistent with the team's 2015 report of a smaller study of the temporal relationship between AF and stroke risk, Dr. Daniel Singer of Massachusetts General Hospital in Boston told Reuters Health by email. (https://bit.ly/2ZXUUx1)

This larger study "provided more precise results... and allowed us to get a better sense of the amount of AF needed to raise stroke risk," he noted.

"Our findings provide support for time-limited (rather than long-term continuous) anticoagulation for patients with infrequent paroxysmal AF (with a high enough CHA2DS2-VASc score), covering the AF episode and for several weeks afterward," he said. "This strategy needs to first be tested in a randomized trial and depends on patients having continuous heart rhythm monitoring, since AF is often asymptomatic."

As reported in JAMA Cardiology, in a case-crossover study, Dr. Singer and colleagues analyzed data from 466,635 patients, including 891 (median age, 76; 64.5% men) who had CIEDs and ischemic stroke with continuous monitoring in the 120 days prestroke.

The primary outcome of the preplanned analysis was the odds ratio for stroke, comparing AF during prestroke days 1-30 (case period) versus 91-120 (control period).

Most patients had either no AF meeting the threshold duration of 5.5 hours or more in both the case and control periods (76.5%), or they had AF of 5.5 hours or more in both periods (16.0%).

Those not meeting the 5.5-hour AF threshold in either period experienced no or very little AF throughout the 120 days prestroke.

Sixty-six patients had informative, discordant arrhythmic states, with 52 having AF of 5.5 hours or more in the case period, versus 14 in the control period (odds ratio, 3.71).

Stroke risk increased most in days 1 to 5 following an AF episode (OR, 5.00), and AF greater than 23 hours on a given day was associated with the clearest increase in stroke risk (OR, 5.00).

Dr. Mintu Turakhia, Director of the Center for Digital Health at Stanford University and author of a related editorial, commented in an email to Reuters Health. "We as clinicians have placed a lot of stock in the risk scores - first CHADS2 and now CHA2DS2-VASC. But it's important to know that these scores are not crystal balls. In fact, they perform very poorly in their ability predict risk of stroke."

"In fact, guidelines recommend keeping patients on lifelong anticoagulation based on data that had only one year of follow-up from a small sample of just over 1,000 patients who had only 25 strokes in total," he said. "These data were from largely hospitalized patients. They really don't apply to the patient who had a small amount of AF detected on monitoring or on a smartwatch."

"The risk of lifelong anticoagulation is that some patients won't stand to benefit from it because their overall stroke risk is low," he explained. "What that means is that they will keep getting exposed to bleeding risk from anticoagulation, but possibly not with benefit for stroke reduction."

Like Dr. Singer, he said, "We need randomized trials to help us determine if it is safe to stop anticoagulation during periods of normal rhythm in patients with infrequent AF and who otherwise have low stroke risk."

"Until then, we have to do the best we can with these imperfect scores. But we will need trials to change practice. Fortunately, several trials are in progress or in development to address this question," Dr. Turakhia concluded.

SOURCE: https://bit.ly/3D9WIkL and https://bit.ly/3it7EC4 JAMA Cardiology, online September 29, 2021

By Marilynn Larkin



Posted on 4 October 20215 October 2021