Implantable loop recorder associated with increased detection of atrial fibrillation post-ischemic stroke compared with external loop recorder

by Jake Engel, Michael Pratte

Originally published by 2 Minute Medicine® (view original article). Reused on AccessMedicine with permission.

1. In patients with recent ischemic stroke and no diagnosed atrial fibrillation (AF), there were increased AF diagnoses in those who received an implantable loop recorder compared with those who received an external loop recorder within 12 months of the intervention.

Evidence Rating Level: 1 (Excellent)

Study Rundown:

Atrial fibrillation (AF) is one of the leading causes of ischemic stroke related to cardiac embolisms. Patients suffering from ischemic stroke without a history of AF should be observed with electrocardiographic monitoring for at least several weeks to determine if they have AF and begin anticoagulation medication. The PER DIEM randomized controlled trial compared AF incidences in patients with ischemic stroke without diagnosed AF using an external loop recorder for 30 days or an implantable loop recorder for 12 months. Three-hundred patients were randomized 1:1 to implantable or external loop recorder, and 259 (126 implantable and 133 external) were available for the 12-month follow-up visit. The development of AF (or highly probable AF) within 12 months was significantly higher in patients who received an implantable loop recorder compared with those with an external loop recorder. Within the first 30 days, there was no significant difference in AF diagnoses between groups; however, between 30 days and 12 months, there were significantly more AF cases in the implantable loop recorder cohort. Post hoc analysis revealed that age and device group were factors associated with the development of new AF diagnoses. The results from this trial indicate that in patients with ischemic stroke and no history of AF, implantable monitoring led to significantly greater detection of AF than external monitoring. One limitation of this study, however, is that monitoring only detected AF if the episode lasted 2 minutes or longer; this may have resulted in some missed diagnoses of AF if the episode was shorter than 2 minutes.

In-Depth [randomized controlled trial]:

This trial enrolled 300 adults (median [interquartile range] age: 64.1 [56.1-73.7] years) who had an ischemic stroke without a history of AF from 3 hospitals in Alberta between May 2015 and November 2017. Half were randomized to receive an implantable loop recorder for 12 months, and half were randomized to receive an external loop recorder for 30 days. The primary outcome was the development of AF (or highly probable AF) lasting for 2 minutes or greater within 12 months of the intervention. AF development within 12 months occurred in 23 out of 150 (15.3%) patients with an implantable loop recorder and 7 out of 150 (4.7%) with an external loop recorder at 12 months (RR: 3.29 [95% CI: 1.45-7.42]; p= 0.003). Within the first 30 days, there was no significant difference in AF diagnoses between groups. However, between 30 days and 12 months, there were 16 (10.7%) diagnoses of AF in the implantable loop cohort and 2 (1.3%) diagnoses of AF in the external loop cohort (RR: 8.00 [95% CI: 1.87-34.19]; p= 0.001). Most secondary outcomes displayed no significant differences between intervention groups. The combined outcome of AF development or death by 12 months was observed in 26 (17.3%) participants in the implantable loop cohort compared with 10 (6.7%) participants in the external loop cohort (HR: 2.64 [95% CI:1.27-5.49]; p= 0.009).

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