Idiopathic 2:1 AV Block With Ventriculophasic Sinus Arrhythmia in a Young Male

Q: What is the clinical evidence from this study?

Study design: Case Report. Population: Idiopathic 2:1 AV block with ventriculophasic sinus arrhythmia (n=1). Intervention: Dual-chamber pacemaker implantation. Primary outcome: Exercise tolerance and cardiac function.

Q: What does this research mean for the field?

Implantation of a dual-chamber pacemaker improves exercise tolerance and maintains preserved left ventricular function over long-term follow-up in young patients with idiopathic 2:1 AV block and ventriculophasic sinus arrhythmia. Novelty: ClaimNovelty.INCREMENTAL. Consensus alignment: ConsensusAlignment.NEUTRAL.

Christopher Tortorici; Gustavo Duarte; Justin D Mark; Roshan Wardak; Jose Muniz; Elias Collado

doi:10.1016/j.jaccas.2026.108790

July 1, 2026JACC Case ReportsOpen Access

Idiopathic 2:1 AV Block With Ventriculophasic Sinus Arrhythmia in a Young Male

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Key result

Dual-chamber pacing preserves LVEF and improves exercise capacity over 5 years in AV block.

n=1

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Graphical abstract published by JACC Case Reports — Graphical abstract · Published by JACC Case Reports · CC BY

Why the study?

Second-degree AV block in young adults is rare and typically associated with structural, infectious, or genetic etiologies, with ventriculophasic sinus arrhythmia rarely described in isolated 2:1 AV block.

Key Points

To describe the clinical presentation, diagnostic evaluation, and management of idiopathic 2:1 atrioventricular block presenting with ventriculophasic sinus arrhythmia in an otherwise healthy young adult.
Evaluated a 23-year-old male presenting with bradycardia (heart rate 38 beats/min) and influenza-like symptoms using electrocardiography, laboratory testing, echocardiography, and cardiac magnetic resonance imaging.
Conducted an exercise stress test with concurrent electrocardiography and echocardiography to assess chronotropic competence and conduction behavior under physiological exertion.
Implanted a dual-chamber permanent pacemaker using a high-septal right ventricular pacing approach, with clinical and device follow-up spanning 5 years.
Electrocardiogram showed 2:1 atrioventricular block with right bundle branch block, right-axis deviation, and ventriculophasic sinus arrhythmia; comprehensive imaging revealed no structural or infiltrative disease.
Exercise testing demonstrated chronotropic incompetence (achieving 32% of maximum predicted heart rate at 11.7 metabolic equivalents) and transient progression to 3:1 and 4:1 atrioventricular block.
Dual-chamber permanent pacing improved exercise tolerance and functional capacity, maintaining preserved left ventricular ejection fraction over 5 years of electrophysiology surveillance.

Study Design

Type

Case Report (n=1)

Structured PICO

P

Population

A 23-year-old male with idiopathic 2:1 AV block and ventriculophasic sinus arrhythmia who received a dual-chamber pacemaker and was followed for 5 years.

I

Intervention

Dual-chamber permanent pacemaker implantation (with high septal right ventricular lead)

O

Outcome

Symptomatic improvement and device function

Ventriculophasic sinus arrhythmia in isolated 2:1 AV block can indicate intrinsic infranodal conduction system disease, supporting the use of early permanent pacing even in minimally symptomatic patients.

Limitations

Inability to achieve selective His capture and precisely localize the level of block
Single patient case report limits generalizability
Genetic testing was deferred by the patient

Implication

May support pacing consideration in select young adults with idiopathic 2:1 AV block; leaves open generalizability without prospective data.

Abstract

BACKGROUND: Second-degree atrioventricular (AV) block in young adults is rare and typically associated with structural, infectious, or genetic etiologies. Ventriculophasic sinus arrhythmia is classically associated with complete heart block and is rarely described in isolated 2:1 AV block. CASE SUMMARY: A 23-year-old male with no prior medical history presented to the clinic with influenza-like symptoms and was incidentally found to have marked bradycardia. Electrocardiogram revealed 2:1 AV Block with right bundle branch block, right-axis deviation, and ventriculophasic sinus arrhythmia. Comprehensive workup excluded structural and infiltrative disease. Exercise stress testing demonstrated transient 3:1 and 4:1 AV block, suggesting infranodal disease. A dual-chamber pacemaker was implanted with improved functional capacity. DISCUSSION: This case highlights a rare presentation of idiopathic 2:1 AV block with ventriculophasic sinus arrhythmia and underscores the diagnostic value of exercise testing. TAKE-HOME MESSAGE: Ventriculophasic sinus arrhythmia in 2:1 AV block may suggest intrinsic conduction system disease and supports early permanent pacing, even in minimally symptomatic patients.

Discussion

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Cite This Study

Tortorici et al. (2026) conducted a case report in Idiopathic 2:1 AV block with ventriculophasic sinus arrhythmia (n=1). Dual-chamber pacemaker implantation was evaluated on Exercise tolerance and cardiac function. Implantation of a dual-chamber pacemaker improved exercise tolerance and preserved left ventricular function over 5 years in a young male with idiopathic 2:1 AV block.

synapsesocial.com/papers/6ad0fc513afa093ea9acfdb8 https://doi.org/10.1016/j.jaccas.2026.108790

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Idiopathic 2:1 AV Block With Ventriculophasic Sinus Arrhythmia in a Young Male

Figures

Key Points

Study Design

Structured PICO

Limitations

Implication

Abstract

Discussion

Cite This Study

Idiopathic 2:1 AV Block With Ventriculophasic Sinus Arrhythmia in a Young Male

Figures

Key Points

Study Design

Structured PICO

Limitations

Implication

Abstract

Discussion

Cite This Study

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