The Heart Rhythm Twins Study

The Heart Rhythm Twins Study -- A Pilot Study in Identical and Fraternal Twins

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.

Study Overview

• Status: Recruiting
• Conditions: Premature Ventricular Contraction; Premature Atrial Complex

• Study Type: Observational
• Enrollment (Anticipated): 120

Contacts and Locations

• Study Contact: Name: Grace Wall; Phone Number: 415-562-5906; Email: grace.wall@ucsf.edu

Study Locations

• United States
  • California
    • San Francisco, California, United States, 94143
      • Recruiting
      • University of California, San Francisco
      • Contact: Grace Wall; Phone Number: 415-562-5906; Email: grace.wall@ucsf.edu
      • Contact: Emilie Frimodt-Møller; Email: emilief_m@hotmail.com
      • Principal Investigator: Greg Marcus, MD, MAS

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: Yes

• Sampling Method: Non-Probability Sample

Study Population

Same-sex sets of twins from anywhere in the world can enroll, as all study procedures can be done remotely. Both twins must enroll to participate.

Description

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 Plan

How is the study designed?

Number of groups / cohorts

2

Cohorts and Interventions

Group / Cohort
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.
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.

What is the study measuring?

Primary Outcome Measures

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

Collaborators and Investigators

• Sponsor: University of California, San Francisco
• Investigators: Principal Investigator: Greg Marcus, MD, MAS, University of California, San Francisco

Study record dates

Study Major Dates

• Study Start (Actual): March 22, 2022
• Primary Completion (Anticipated): January 1, 2024
• Study Completion (Anticipated): January 1, 2024

Study Registration Dates

• First Submitted: May 10, 2023
• First Submitted That Met QC Criteria: May 10, 2023
• First Posted (Actual): May 19, 2023

Study Record Updates

• Last Update Posted (Actual): May 19, 2023
• Last Update Submitted That Met QC Criteria: May 10, 2023
• Last Verified: May 1, 2023

More Information

Terms related to this study

• Keywords: twin
• Additional Relevant MeSH Terms: Pathologic Processes; Heart Diseases; Cardiovascular Diseases; Arrhythmias, Cardiac; Cardiac Conduction System Disease; Cardiac Complexes, Premature; Ventricular Premature Complexes; Atrial Premature Complexes
• Other Study ID Numbers: 21-35126

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No