Prevalence and Prognostic Significance of Bradyarrhythmias in Patients Screened for Atrial Fibrillation vs Usual Care Post Hoc Analysis of the LOOP Randomized Clinical Trial

The study aimed to evaluate the prevalence and prognostic significance of bradyarrhythmias in persons screened for atrial fibrillation (AF) using an implantable loop recorder (ILR) compared to unscreened persons. The post-hoc analysis of the Implantable Loop Recorder Detection of Atrial Fibrillation to Prevent Stroke (LOOP) randomized clinical trial involved 6004 participants aged 70 years or older without known AF but diagnosed with hypertension, diabetes, heart failure, or prior stroke. The ILR group underwent screening for AF, while the control group received usual care. The study found that 20.8% of the ILR group were diagnosed with bradyarrhythmia compared to 3.8% in the control group. The most common bradyarrhythmia was sinus node dysfunction followed by high-grade atrioventricular block. Risk factors for bradyarrhythmia included higher age, male sex, and prior syncope. A pacemaker was implanted in 4.5% of the ILR group compared to 2.9% in the control group. Bradyarrhythmias were associated with subsequent syncope, cardiovascular death, and all-cause death, with no difference in risk between the two groups.

The study suggests that more than one in five persons over the age of 70 with cardiovascular risk factors can be diagnosed with bradyarrhythmias when long-term continuous monitoring for AF is applied. ILR screening led to a 6-fold increase in bradyarrhythmia diagnoses and a significant increase in pacemaker implantations compared to usual care, but no change in the risk of syncope or sudden death. The findings highlight the importance of heart rhythm monitoring and technologies to detect subclinical AF and incidentally diagnose bradyarrhythmias in high-risk patients.

doi:10.1001/jamacardio.2022.5526


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