The Heart Rhythm Twins Study

NCT ID: NCT05866731

Last Updated: 2025-10-24

Basic Information

• Recruitment Status: ACTIVE_NOT_RECRUITING
• Total Enrollment: 120 participants
• Study Classification: OBSERVATIONAL
• Study Start Date: 2022-03-22
• Study Completion Date: 2025-12-31

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.

Conditions

Premature Atrial Complex; Premature Ventricular Contraction

Study Design

• Observational Model Type: COHORT
• Study Time Perspective: PROSPECTIVE

Study Groups

Identical twins

60 identical twins (30 sets) will be enrolled. Participants will answer 15-20 minutes of questionnaires on demographics, lifestyle, medical history, and family history over Zoom or the phone with a study coordinator. Participants will then be mailed an iRhythm Zio XT heart rhythm monitor, or EKG, to apply and wear for a maximum of 2 weeks, as well as a DNA Genotek saliva collection kit to collect a small saliva sample. Participants will return the monitor and saliva sample to the study team, and will be reimbursed upon return. The study team is also requesting photo validation to verify twin status.

No interventions assigned to this group

Same-sex fraternal twins

60 same-sex fraternal twins (30 sets) will be enrolled. Participants will answer 15-20 minutes of questionnaires on demographics, lifestyle, medical history, and family history over Zoom or the phone with a study coordinator. Participants will then be mailed an iRhythm Zio XT heart rhythm monitor, or EKG, to apply and wear for a maximum of 2 weeks, as well as a DNA Genotek saliva collection kit to collect a small saliva sample. Participants will return the monitor and saliva sample to the study team, and will be reimbursed upon return. The study team is also requesting photo validation to verify twin status.

No interventions assigned to this group

Eligibility Criteria

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

• Minimum Eligible Age: 18 Years
• Eligible Sex: ALL
• Accepts Healthy Volunteers: Yes

Sponsors

University of California, San Francisco

OTHER

Sponsor Role: lead

Responsible Party

Responsibility Role: SPONSOR

Principal Investigators

Greg Marcus, MD, MAS

Role: PRINCIPAL_INVESTIGATOR

University of California, San Francisco

Locations

University of California, San Francisco

San Francisco, California, United States

Countries

United States

Other Identifiers

21-35126

Identifier Type: -

Identifier Source: org_study_id