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Nocturnal Atrioventricular Block: Natural History and Clinical Implications
Soyoon Park1, Soohyun Kim2, Hwa Jung Kim3
1Division of Cardiology, Department of Internal Medicine, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Korea.
Journal of Korean Medical Science
|February 24, 2026
Summary
Nocturnal atrioventricular block (AVB) may require pacemaker implantation, even if asymptomatic during the day. Active surveillance is recommended for patients with nocturnal AVB due to potential daytime complications.
Area of Science:
- Cardiology
- Electrophysiology
Background:
- Nocturnal atrioventricular block (AVB) was traditionally attributed to vagal tone with a favorable prognosis.
- Evidence supporting the management of nocturnal AVB, particularly regarding pacemaker implantation, is limited.
Purpose of the Study:
- To assess the natural history of nocturnal atrioventricular block (AVB).
- To determine the need for pacemaker implantation in patients with exclusively nocturnal AVB.
Main Methods:
- Patients with 2:1, high-degree, or complete AVB (CAVB) exclusively during nighttime (21:00-07:00) on 24-hour ECG monitoring were identified.
- The primary outcome was pacemaker implantation during follow-up.
Main Results:
- Out of 10,977 individuals, 92 had nocturnal AVB; 81 were enrolled after exclusions.
- Fourteen patients received immediate pacemaker implantation for daytime symptoms.
- During a median 2.4-year follow-up, 21% (14/67) of the remaining patients required pacemaker implantation for daytime bradycardia or sick sinus syndrome.
Conclusions:
- Nocturnal AVB, even without daytime symptoms, may necessitate pacemaker implantation.
- Active surveillance is crucial for patients diagnosed with nocturnal AVB.
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