May 16, 2018
2 min read

KP-RHYTHM: Greater AF burden increases risk for ischemic stroke

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Alan S. Go, MD
Alan S. Go

Among patients with paroxysmal atrial fibrillation, greater AF burden was linked to an increased risk for ischemic stroke independent of known risk factors, according to a study published in JAMA Cardiology.

Monitoring in paroxysmal AF

Alan S. Go, MD, director of the comprehensive clinical research unit and regional medical director of clinical trials at The Permanente Medical Group in Oakland, California; associate professor in the departments of epidemiology, biostatistics and medicine at the University of California, San Francisco; and consulting professor of health research and policy at Stanford University, and colleagues of the KP-Rhythm study analyzed data from 1,965 patients (mean age, 69 years; 45% women) with paroxysmal AF who underwent continuous ambulatory ECG monitoring with a wearable patch (Zio Patch, iRhythm Technologies) between October 2011 and October 2016. The patch is designed to be worn during normal activities and records each heartbeat for analysis.

Patients were followed up from the end of monitoring through November 2016. During the study, patients were censored for health plan disenrollment, death or end of follow-up.

The outcome of interest was hospitalization for arterial thromboembolism or ischemic stroke while not taking anticoagulants. Events were identified through hospital discharge and ED databases, and physicians adjudicated medical records.

Patients were stratified into tertiles by AF burden.

The median CHA2DS2-VASc score was 3, and the median Anticoagulation and Risk Factors in Atrial Fibrillation (ATRIA) stroke risk score was 4. The burden of AF was a median of 4.4%. Those with a higher burden of AF had more cardioversion attempts and were less likely to be Hispanic or women.

Thromboembolism without anticoagulants

Compared with the two lower tertiles of AF burden, patients in the highest tertile of AF burden were three times as likely to have a thromboembolism while not taking anticoagulants after adjusting for CHA2DS2-VASc score (adjusted HR = 3.16; 95% CI, 1.51-6.62) or ATRIA score (aHR = 3.13; 95% CI, 1.5-6.56).

Similar results were seen in demographic and clinical subgroups.

Jonathan P. Piccini, MD, MHS, FACC, FAHA, FHRS
Jonathan P. Piccini

“Characterizing the burden of atrial fibrillation in patients with paroxysmal atrial fibrillation could assist patients and physicians in having a more informed, shared decision-making discussion about stroke prevention strategies,” Go and colleagues wrote.

“These data may have important implications for treating patients with paroxysmal AF and low CHA2DS2-VASc scores,” Benjamin A. Steinberg, MD, MHS, assistant professor of medicine in the division of cardiovascular medicine at University of Utah Health Sciences Center in Salt Lake City, and Jonathan P. Piccini, MD, MHS, associate professor of medicine at Duke University Medical Center and member in the Duke Clinical Research Institute, wrote in a related editorial. “In these low-risk patients, increased AF burden may identify those with additional and actionable stroke risk in whom the net clinical benefit of [oral anticoagulation] is favorable. Given the pervasive and growing use of continuous electrocardiographic monitoring, it is high time for a randomized clinical trial of AF burden-guided [oral anticoagulation] among patients with low CHA2DS2-VASc scores (0-1).” – by Darlene Dobkowski

Disclosures: This study was supported by a research grant from iRhythm Technologies. Go reports no relevant financial disclosures. Piccini reports he received funding for clinical research from Abbott Medical, ARCA Biopharma, Boston Scientific, Gilead, Janssen Pharmaceuticals and Verily, and serves as a consultant to Allergan, Bayer, Johnson & Johnson, Medtronic, Phillips and Sanofi. Steinberg reports he received research support from Boston Scientific and Janssen, and consultant fees from Biosense Webster. Please see the study for all other authors’ relevant financial disclosures.