Implantable loop recorder screening for AF not linked to stroke reduction risk

Implantable loop recorder screening for atrial fibrillation did not significantly reduce the risk for stroke compared with usual care, according to study results published in JAMA Neurology.

“Stroke is a leading cause of mortality and disability throughout the world,” Soren Zoga Diederichsen, MD, PhD, of the department of cardiology at Copenhagen University Hospital in Denmark, and colleagues wrote. “Atrial fibrillation is an important and often undiagnosed risk factor for stroke.”

Researchers aimed to assess the characteristics of stroke in patients undergoing implantable loop recorder (ILR) screening for atrial fibrillation (AF) compared with usual care, while also determining the importance of prior stroke.

Diederichsen and colleagues conducted a post hoc analysis of the Atrial Fibrillation Detected by Continuous Electrocardiogram Monitoring Using Implantable Loop Recorder to Prevent Stroke in High-Risk Individuals (LOOP) randomized clinical trial, which recruited participants from four sites in Denmark from January 2014 to May 2016.

The trial drew from an initial pool of 6,205 individuals, aged 70 years or older, without known AF but diagnosed with hypertension, diabetes, heart failure or prior stroke. A total of 6,004 individuals were then randomized on a 2:1 basis for either usual care (n = 4,503; mean age, 74.7 years; 52.7% men) or ILR (n = 1,501; mean age, 74.7 years; 52.8% men). The median follow-up period was 65 months, and the main outcome was adjudicated stroke, with severity assessed via the modified Rankin Scale (mRS; 3 as a cutoff for either disabling or lethal stroke) and etiology classified according to the Trial of Org 10172 in Acute Stroke Treatment for ischemic strokes.

Results showed that 794 of 4,503 participants (17.6%) in the control group had a history of prior stroke compared with 262 of 1,501 participants (17.5%) in the ILR group. During follow-up, AF was diagnosed in 1,027 participants (control group = 550, ILR group = 477), with anticoagulation started in 89% of these patients. A total of 315 participants (5.2%) had a stroke (control group = 249, ILR group = 66), with a median mRS score of 2 among both groups.

Data additionally revealed that 272 participants had ischemic stroke (control group = 217, ILR group = 55), and 123 (2.0%) had severe stroke (control group = 100, ILR group = 23). The hazard ratios comparing control and ILR groups were 0.76 (95% CI, 0.57-1.03) and 0.69 (95% CI, 0.44-1.09), respectively, and 0.68 (95% CI, 0.48-0.97) and 0.54 (95% CI, 0.30-0.97), respectively, for participants without prior stroke.

“Screening did not result in a significant reduction in disabling or lethal stroke,” Diederichsen and colleagues wrote.