The Heart Rhythm Twins Study

Active, not recruiting

• Conditions: Premature Atrial Complex; Premature Ventricular Contraction

• Registration Number: NCT05866731
• Lead Sponsor: University of California, San Francisco

Brief Summary

Premature atrial contractions (PACs) and premature ventricular contractions (PVCs) are observed in the majority of individuals monitored for more than a few hours. Although the clinical course of PACs and PVCs is usually benign, it has been described that high PAC or PVC frequency causes various comorbidities and worsens outcomes in different patient groups. For example, PACs can initiate episodes of atrial fibrillation, and PAC count is highly specific in predicting diagnosis of incident atrial fibrillation. Increasing PVC frequencies are an important predictor of incident heart failure.

While conventional wisdom dictates that common environmental exposures determine PAC and PVC frequencies, this has not born out in rigorous studies. Whether PAC and PVC frequencies may have genetic underpinnings remains unknown.

Comparisons between identical twins and fraternal twins can provide estimates of heritability. Fraternal twins are an ideal control because, like identical twins, they share a womb, have the same birthday, and their environment while growing up are as similar as between identical twins. However, while identical twins share approximately 100% of the same inherited DNA, fraternal twins share, on average, about 50%. By monitoring identical and fraternal twins with portable electrocardiograms (ECGs), we will be able to count the PACs and PVCs over a consecutive timespan to describe the familial aggregation of these complexes. This, to our knowledge, would be the first study to compare PAC and PVC frequencies in identical and same-sex fraternal twins, providing the first assessment of how genetical inheritance may influence cardiac ectopy burdens.

Detailed Description

Not available

Study Timeline

• Study Start: 2022-03-22
• Study First Submitted: 2023-05-10
• Study First Submitted QC: 2023-05-10
• Study First Posted: 2023-05-19
• Status Verified: 2025-05
• Last Update Submitted: 2025-05-01
• Last Update Posted: 2025-05-06
• Primary Completion: 2025-08-01
• Study Completion: 2025-08-01

Recruitment & Eligibility

• Status: ACTIVE_NOT_RECRUITING
• Sex: All
• Target Recruitment: 120

Inclusion Criteria

• Identical or same-sex fraternal sets of twins
• English-speaking

Exclusion Criteria

• Pregnancy
• Current anti-arrhythmic medication use (including beta blockers)
• Diagnosis of congenital heart disease
• Diagnosis of persistent or permanent atrial fibrillation
• Prior cardiac ablation

Study & Design

• Study Type: OBSERVATIONAL
• Study Design: Not specified

Primary Outcome Measures

Name	Time	Method
Frequency of premature ventricular contractions (PVCs)	Maximum of 2 weeks	This will be measured using a wearable EKG monitor.
Frequency of premature atrial contractions (PACs)	Maximum of 2 weeks	This will be measured using a wearable EKG monitor.

Trial Locations

Locations (1)

University of California, San Francisco; 🇺🇸 San Francisco, California, United States