CHICAGO (FRONTLINE MEDICAL NEWS) One-third of a large cohort of patients with an implantable cardiac device in place at the time of an ischemic stroke had one or more episodes of atrial fibrillation within the prior 30 days, Dr. Rhea C. Pimentel reported at the annual meeting of the American College of Cardiology.

The in-hospital mortality rate of these atrial fibrillation–related strokes was high: 11 of 42 (26%) such patients died during their stroke hospitalization, compared with 6 of 83 (7%) whose strokes were not temporally related to atrial fibrillation (AF), noted Dr. Pimentel , an electrophysiologist at the University of Kansas Medical Center in Kansas City.

Data from the Framingham Heart Study and other sources suggest that stroke in patients who have AF carries about double the mortality rate of strokes in patients without AF. Mortality associated with AF-related stroke in the Kansas study was probably so much higher because the hospital serves as a comprehensive stroke center, drawing patients from considerable distances across the Midwest, she said.

Dr. Pimentel reported on 125 patients who presented with an ischemic stroke when a cardiac monitoring device was in place. This is believed to be the largest such patient series ever reported. Their mean age was 73 years, and 41% were women. The mean CHADS2 score was 3.96, with a CHA2DS2-VASc score of 5.28. Of the patients, 62% had a pacemaker; the rest had an implantable cardioverter-defibrillator or cardiac resynchronization device. One-quarter of the group had a prior history of AF, and a fifth were on an oral anticoagulant – warfarin, in 70% of cases – at the time of their stroke.

The investigators defined a stroke-related AF episode as a total of at least 1 hour spent in AF during the 30 days preceding the stroke. Eighty percent of affected patients had paroxysmal AF. They typically fulfilled the 1-hour AF requirement via multiple short, self-terminated episodes rather than in an hour-long episode.

Being on an oral anticoagulant had no impact on in-hospital mortality, which was 14.2% in patients on warfarin or a newer anticoagulant and 14.3% in those who were not. Dr. Pimentel noted that she was presenting the results of the investigators’ initial look at the data. They are in the process of obtaining the patients’ international normalized ratio data, which “should be very enlightening,” she said.

She and her coinvestigators also plan to subdivide their 30-day study period into 5-day segments to learn just how soon after an AF episode the strokes occurred. Researchers at Stanford (Calif.) University have reported that the greatest stroke risk in patients with AF is in the first 5 days after an AF episode, and the Kansas group would like to confirm that observation.

In addition, because it remains an unresolved question whether any amount of AF is safe, Dr. Pimentel and her coworkers are considering reanalyzing their data using a cutoff of 6 minutes of AF rather than 1 hour during the 30 days prior to stroke.

The study was conducted free of commercial support. Dr. Pimentel reported having no relevant financial conflicts.