Bradyarrhythmias risk markers but their detection not associated with reduced clinical outcomes: JAMA

The incidental diagnosis of bradyarrhythmias is common due to heart rhythm monitoring and technologies to detect subclinical atrial fibrillation (AF).

The question here is, what is the expected outcome of this incidentally diagnosed bradyarrhythmias?

Researchers assessed the prevalence and prognostic significance of Bradyarrhythmia in those who are screened for Atrial Fibrillation using an implantable loop recorder (ILR) than unscreened persons (LOOP RCT).

The study points include the following:

• The study was conducted in Denmark at four sites.
• A total of 6004 study participants were 70 years or older, with 47.3 % female and or older without known AF, but these were diagnosed with one of the following, including hypertension, diabetes, heart failure, or prior stroke.
• The participants were followed-up for 65 months.
• Bradyarrhythmia, pacemaker, syncope, and sudden cardiovascular death.
• Five thousand four hundred forty-four study participants constituting 90.7%, had hypertension.
• One thousand two hundred twenty-four study participants constituting 20.4%, had prior syncope.
• One hundred seventy-two participants in the control group and 312 in the ILR group were diagnosed with Bradyarrhythmia in the control group with a hazard ratio of 6.2 and were asymptomatic in 41 participants vs 249 participants constituting 23.8 % and 79.8 %, respectively.
• Sinus node dysfunction was most common, followed by high-grade atrioventricular block.
• Risk factors were age, male sex, and prior syncope.
• A pacemaker was implanted in 132 participants constituting 2.9%, versus 67 participants constituting 4.5%, with an HR of 1.53.
• The syncope occurred in 120 participants versus vs 33 participants, with HR of 0.83 in the control and ILR groups, respectively.
• Bradyarrhythmias were related to syncope, cardiovascular death, and all-cause death. There was no interaction between the bradyarrhythmia and the randomization group.

The diagnosis of bradyarrhythmia increased by 6-fold, and a significant increase in pacemaker implantations due to screening when compared with usual care.

There were no changes in the risk of syncope or sudden death.

Further reading:

Diederichsen SZ et al. Prevalence and Prognostic Significance of Bradyarrhythmias in Patients Screened for Atrial Fibrillation vs Usual Care: Post Hoc Analysis of the LOOP Randomized Clinical Trial. JAMA Cardiol. Published online February 15, 2023. doi:10.1001/jamacardio.2022.5526