NEW YORK (Reuters Health) – Brief episodes of atrial tachyarrhythmia detected by cardiac rhythm management devices were not linked with an increased risk of clinical events in a recent registry study.

“The most important finding is that short episodes of atrial fibrillation (AF), as defined, were not associated with increased risk of clinical events, including stroke, and therefore a patient with only short episodes need not be anticoagulated, other things equal,” Dr. Steven Swiryn from Feinberg School of Medicine at Northwestern University in Chicago told Reuters Health by email.

Anticoagulation is recommended for prolonged episodes of device-documented atrial tachycardia (AT) and/or fibrillation because of their association with an increased risk of clinical events, including stroke, but the appropriate clinical response to brief episodes of device-detected AT/AF remains unclear.

Dr. Swiryn’s team used data from the prospective Registry of Atrial Tachycardia and Atrial Fibrillation Episodes to evaluate the clinical implications, if any, of brief episodes of device-detected AT/AF in 300 randomly chosen pacemaker patients and 300 randomly chosen patients with an implantable cardioverter-defibrillator (ICD).

They defined short episodes of AT/AF as those where the onset and offset of an episode were documented within the same electrogram recording and long episodes of AT/AF as those where the onset and/or the offset of an episode was not documented within the same recording.

About half of the patients had at least one atrial recording during follow-up demonstrating AT/AF, with 9% of pacemaker patients and 16% of ICD patients having only short episodes and no long episodes over their entire follow-up, according to the report online October 17th in Circulation.

Among both pacemaker and ICD patients, there was no statistically significant association of short episodes of AT/AF with clinical outcomes.

Long episodes of AT/AF were associated with an increased risk of all clinical events, hospitalization for clinical AT/AF, and all-cause mortality among ICD patients but not among pacemaker patients. There was no association between long AT/AF and stroke in either group.

During two years of follow-up, about 55% of pacemaker patients and 45% of ICD patients whose initial AT/AF episode was short had at least one long episode documented later in follow-up. In a multivariable model, occurrence of long AT/AF was associated with a significantly higher risk of clinical events, compared with patients who had no AT/AF, whereas having only short AT/AF was associated with a significantly lower risk of any event.

Similarly, long AT/AF was associated with a 51% increased risk of incident stroke or TIA, whereas the likelihood of stroke or TIA did not differ significantly between patients with only short AT/AF and no AT/AF.