Study: No Link Between Atrial Tachyarrhythmias and Stroke Risk

New research finds that patients with pacemakers or implantable cardioverter-defibrillators (ICDs) who experience brief episodes of atrial tachyarrhythmia are not at greater risk of stroke or other clinical events.

A team of investigators enrolled 5379 patients with pacemakers (n=3141) or ICDs (n=2238) at 225 United States-based sites. Over a median follow-up period of 22.9 months, there were 359 deaths. In addition, the authors observed 478 hospitalizations among 342 patients for clinical events, and found that patients with clinical events were more likely than those without to have long atrial tachycardia and/or atrial fibrillation (AT/AF)—31.9% compared with 22.1% for pacemaker patients and 28.7% vs 20.2% for ICD patients.
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Only short episodes of AT/AF were documented in 9% of pacemaker patients and 16% of ICD patients. Patients with clinical events were no more likely than those without to have short AT/AF—5.1% vs 7.9% for pacemaker patients, and 11.5% vs 10.4% for ICD patients.

"Both cardiologists and primary care physicians probably tend to underprescribe rather than overprescribe anticoagulation in patients with atrial fibrillation," said Steven Swiryn, MD, a clinical professor of medicine at the Feinberg School of Medicine at Northwestern University in Chicago, and lead author of the study.

For example, he says, "Many of us are hesitant to anticoagulate our older patients, even though published data show that risk of stroke rises with age much faster than risk of bleeding, arguing that many of these patients would benefit."

Clinicians are often faced with reports of patients with implanted pacemakers or ICDs in which the device records episodes of atrial fibrillation that were clinically silent. "The question is how to react, especially [with respect to] anticoagulating such patients," Dr Swiryn said, adding that there is increasing evidence that prolonged episodes of atrial fibrillation in that setting are associated with the risk of stroke.

Therefore, he said, "If the risk of stroke, as assessed with a CHA₂DS₂-VASc score, for example, is high enough, anticoagulation is likely to be indicated," Dr Swiryn said.

The results of the RATE Registry (Registry of Atrial Tachycardia and Atrial Fibrillation Episodes) show that the risk of stroke is low in patients with only brief episodes of atrial fibrillation, defined as episodes where both the onset and the offset are documented by the device within the same electrocardiogram. "Such patients are unlikely to benefit from immediate anticoagulation," Dr Swiryn said. "However, some of those patients go on to have more prolonged episodes of atrial fibrillation with further follow-up and, therefore, continued monitoring will be needed."

—Mark McGraw

Reference:

Swiryn S, Orlov MV, Benditt DG, et al; RATE Registry Investigators. Clinical implications of brief device-detected atrial tachyarrhythmias in a cardiac rhythm management device population: results from the Registry of Atrial Tachycardia and Atrial Fibrillation Episodes. Circulation. 2016;134(16):1130-1140.