Severity and Etiology of Incident Stroke in Patients Screened for Atrial Fibrillation vs Usual Care and the Impact of Prior Stroke

Abstract

IMPORTANCE Atrial fibrillation (AF) screening trials have failed to demonstrate a significant reduction in stroke risk. The impact on stroke severity and the importance of prior strokes are unknown.OBJECTIVE To assess stroke characteristics in patients undergoing implantable loop recorder (ILR) screening for AF vs usual care and assess the importance of prior stroke. DESIGN, SETTING, AND PARTICIPANTSThis was 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. Persons 70 years or older without known AF but diagnosed with 1 or more of the following, hypertension, diabetes, heart failure, or prior stroke, were screened for inclusion. Four sites in Denmark recruited participants by letter between January 31, 2014, and May 17, 2016. The median (IQR) follow-up period was 65 (59-70) months. Data were analyzed from April 1 to May 31, 2022. INTERVENTIONS ILR screening for AF and anticoagulation initiation if AF duration of 6 minutes or longer was detected (ILR group) vs usual care (control group). MAIN OUTCOMES AND MEASURES Adjudicated stroke, classified according to the modified Rankin Scale (mRS) using a score of 3 or more as a cutoff for severe (disabling or lethal) stroke, and according to the Trial of Org 10172 in Acute Stroke Treatment (TOAST) classification for ischemic strokes. RESULTS A total of 6205 individuals were screened for inclusion, and 6004 were randomized and included in the analysis; 4503 participants (75%; mean [SD] age, 74.7 [4.1] years; 2375 male [52.7%]) were assigned to the control group and 1501 participants (25%; mean [SD] age, 74.7 [4.1] years; 792 male [52.8%]) were assigned to the ILR group. A total of 794 of 4503 participants (17.6%) in the control group had a history of prior stroke compared with 262 of 1501 participants (17.5%) in the ILR group. During follow-up, AF was diagnosed in 1027 participants (control group, 550 [12%] vs ILR group, 477 [32%]), and anticoagulation was initiated in 89% of these (910). A total of 315 participants (5.2%) had a stroke (control group, 249 [5.5%] vs ILR group, 66 [4.4%]), and the median (IQR) mRS score was 2 (1-3) with no difference across the groups. A total of 272 participants (4.5%) had ischemic stroke (control group, 217 [4.8%] vs ILR group, 55 [3.7%]), and 123 (2.0%) had severe stroke (control group, 100 [2.2%] vs ILR group, 23 [1.5%]), and the hazard ratios comparing the control and ILR groups were 0.76 (95% CI, 0.57-1.03; P = .07) and 0.69 (95% CI, 0.44-1.09; P = .11), respectively. For participants without prior stroke, the hazard ratios were 0.68 (95% CI, 0.48-0.97; P = .04) and 0.54 (95% CI, 0.30-0.97; P = .04), respectively. CONCLUSIONS AND RELEVANCEThis post hoc analysis of the LOOP randomized clinical trial found that ILR screening for AF did not result in a significant decrease in ischemic or severe strokes compared with usual care. Exploratory subgroup analyses indicated a possible red...

Implantable loop recorder detection for atrial fibrillation to prevent stroke in high-risk patients

“…4 Contraindications ILR implantation is contraindicated when there is no indication for its use, the patient has an active infection, or when a patient has an uncorrected bleeding disorder. [5][6][7][8] Post-procedure ILR patient education 5…”

“…7 The control group had more bleeding episodes, accounting for 156 compared with 65 in the ILR group. 8 The researchers concluded that ILR screening resulted in a three-times increase in AF detection and anticoagulation initiation in individuals with stroke risk factors but no significant reduction in the risk of stroke or systemic arterial embolism. The researchers further stated that their findings might imply that it is not worth screening for all AF and that not all screen-detected AF merits anticoagulation.…”

“…The researchers further stated that their findings might imply that it is not worth screening for all AF and that not all screen-detected AF merits anticoagulation. 8 A post hoc analysis of the LOOP randomized clinical trial was conducted to assess stroke characteristics in patients undergoing ILR screening for AF versus usual care and assess the importance of prior stroke.…”

The gray areas of oral anticoagulation for prevention of thromboembolic events in atrial fibrillation patients

“…33 On the other hand, a post hoc randomized clinical trial of implantable loop recorder (ILR) screening for AF vs. usual care in individuals aged !70 years with risk factors did not find a significant reduction in disabling or lethal stroke; while cardioembolism was relatively rare, observed strokes were ischemic, mostly due to small-vessel disease, and AF detection by ILR was associated with more severe events compared with the undetected ones. 34 Current recommendations on AHREs detected by implanted devices are to consider them as innocent bystanders when they are of short duration and occur in patients with low/intermediate TEE risk. On the other hand, AHREs longer than 24 h in high TEE risk patients would recommend starting anticoagulation; in any event, closer follow-up visits for AF development are mandatory.…”

Error in Text

“…The Original Investigation “Severity and Etiology of Incident Stroke in Patients Screened for Atrial Fibrillation vs Usual Care and the Impact of Prior Stroke: A Post Hoc Analysis of the LOOP Randomized Clinical Trial,” published online August 29, 2022, had an error in the Statistical Analysis section of the text. The cutoff for statistical significance should read P < .05 rather than P > .05.…”