Short episodes of atrial fibrillation or tachycardia in people with pacemakers or defibrillators did not increase the risk for stroke or other clinical events, according to new data from the RATE Registry.
“Other studies have shown that prolonged episodes of AF pose a risk, but what about short ones?” Steven Swiryn, MD, clinical professor of cardiology at the Feinberg School of Medicine at Northwestern University, said in a press release. “The answer until this study was ‘no one knows.’ Now we have good solid data that if all you have is short episodes of AF, the risk is so low that it doesn’t warrant anticoagulants.”
Researchers analyzed 37,500 ECGs from 5,379 patients at 225 U.S. sites enrolled in the RATE Registry. Of those, 3,141 patients had pacemakers and 2,238 had ICDs (St. Jude Medical products). Median follow-up was 23 months.
Overall, 359 patients died during the follow-up period. Hospitalizations due to clinical events occurred in 342 patients (478 hospitalizations total).
When the researchers adjudicated the 37,500 ECGs, half of the patients had one or more episodes of atrial tachycardia (AT) or AF.
According to the findings, patients with clinical events were more likely to have long episodes of AT/AF compared with patients without clinical events. Among patients with pacemakers, the rate of long AT/AF was 31.9% in those with clinical events vs. 22.1% in those without clinical events (P < .05). Among patients with ICDs, the rate of long AT/AF was 28.7% in those with clinical events vs. 20.2% in those without clinical events (P < .05).
Short episodes of AT/AF were documented in 9% of patients with pacemakers and 16% of patients with ICDs. The rate of short AT/AF was similar between patients with and without clinical events. Among patients with pacemakers, the rate of short AT/AF was 5.1% in those with clinical events vs. 7.9% in those without clinical events (P = .21). Among patients with ICDs, the rate of short AT/AF was 11.5% in those with clinical events vs. 10.4% in those without clinical events (P = .66).
“The rate of progression to long AT/AF did not differ significantly between patients with initially only short AT/AF vs. no AT/AF, but progression from short to longer episodes was observed in some patients, and the association was of borderline statistical significance,” the researchers wrote.
Swiryn and colleagues called for continued monitoring of patients for progression to prolonged episodes of AT/AF that may develop. – by Dave Quaile
Disclosure: The RATE Registry was funded by St. Jude Medical. Swiryn reports receiving consultant fees from St. Jude Medical.