Premature Atrial ComplexNCT05866731
The Heart Rhythm Twins Study
An observational study of Premature Atrial Complex and Premature Ventricular Contraction, run by University of California, San Francisco at 1 site in United States.
Trial 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… Read more about this study
- Who is it for?
- Ages 18 years and olderHealthy volunteers can take part
- Conditions the study is for
- Premature Atrial Complex, Premature Ventricular Contraction
- How many people
- 156 participants
- Where
- 1 siteUnited States
- Study dates
- 22 Mar 2022to 18 Aug 2025
- Phase
- Observational
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 years and older
- All sexes
- Healthy volunteers accepted
- Adult, Older adult
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.
Who may be able to join
- Identical or same-sex fraternal sets of twins
- English-speaking
Who cannot join
- Pregnancy
- Current anti-arrhythmic medication use (including beta blockers)
- Diagnosis of congenital heart disease
- Diagnosis of persistent or permanent atrial fibrillation
- Prior cardiac ablation
Trial locations and contacts
1 site in 1 country.
United States1 site
University of California, San Francisco
San Francisco, California, 94143
About this study
Official title: 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.
- Keywords
- twin
- Medical subject headings
- Atrial Premature Complexes, Ventricular Premature Complexes
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
| Study group | Role | What they receive |
|---|---|---|
| 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 being measured
The primary outcome is the main question the study is designed to answer.
Frequency of premature atrial contractions (PACs)
This will be measured using a wearable EKG monitor.
Measured: Maximum of 2 weeks
Frequency of premature ventricular contractions (PVCs)
This will be measured using a wearable EKG monitor.
Measured: Maximum of 2 weeks
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted19 May 2023
- Study start22 Mar 2022
- Primary completion16 Mar 2025
- Study completion18 Aug 2025
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Premature Atrial ComplexStudies of the same condition, open and under way.
- More trials run by University of California, San FranciscoThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Observational
- Observational model
- Cohort
- Time perspective
- Prospective
- Enrolment
- 156 participants (actual)
Sponsor and investigators
- Lead sponsor
- University of California, San Francisco
- Sponsor type
- University, hospital or other
- Responsible party
- Sponsor
- Investigators
- Greg Marcus, MD, MAS, Principal investigator, University of California, San Francisco
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT05866731
- Sponsor's protocol ID
- 21-35126
- Status last verified
- Mar 2026
- First submitted
- 10 May 2023
- Last updated
- 9 Mar 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No
Study at a glance
From the registry record, last updated by the sponsor on 9 Mar 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- The Heart Rhythm Twins Study -- A Pilot Study in Identical and Fraternal Twins
- ClinicalTrials.gov ID
- NCT05866731
- Acronym / sponsor ID
- 21-35126
- Keywords
- twin
- Study type
- Observational
- Recruitment status
- Completed
- Enrolment
- 156 participants (actual)
- Lead sponsor
- University of California, San FranciscoUniversity, hospital or other
- Study start
- 22 Mar 2022 (actual)
- Primary completion
- 16 Mar 2025 (actual)
- Study completion
- 18 Aug 2025 (actual)
- First posted
- 19 May 2023 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
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 design
- Observational model
- Cohort
- Time perspective
- Prospective
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| 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. |
Who may qualify
- Ages
- 18 years and older
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult, Older adult
- 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.
Key inclusion criteria (2 listed)
- Identical or same-sex fraternal sets of twins
- English-speaking
Key exclusion criteria (5 listed)
- Pregnancy
- Current anti-arrhythmic medication use (including beta blockers)
- Diagnosis of congenital heart disease
- Diagnosis of persistent or permanent atrial fibrillation
- Prior cardiac ablation
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Primary outcome
Frequency of premature atrial contractions (PACs)
Time frame: Maximum of 2 weeks
This will be measured using a wearable EKG monitor.
Frequency of premature ventricular contractions (PVCs)
Time frame: Maximum of 2 weeks
This will be measured using a wearable EKG monitor.
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 9 Mar 2026.
- Individual participant dataSharing planned: No
Related trials for Premature Atrial Complex
Recruiting
Disrupted Sleep and Concurrent Ectopy or Atrial Fibrillation
Obstructive Sleep Apnea, Premature Ventricular Contraction (PVC)
Recruiting
A Study Assessing Arrhythmia Mapping With a Multi-Electrode Mapping Catheter
Scar-related Atrial Tachycardia, Persistent Atrial Fibrillation
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Biospecimen Repository for Cardiac Arrhythmias at the Cleveland Clinic
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Defining the Risk of Ventricular Tachycardia in Genetic Cardiomyopathies
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The MAGiC™ Cardiac Ablation European Study
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Greg Marcus, MD, MAS principal investigator
University of California, San Francisco
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
An observational study of Premature Atrial Complex and Premature Ventricular Contraction, run by University of California, San Francisco at 1 site in United States.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 2 inclusion and 5 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 9 Mar 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in United States. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Frequency of premature atrial contractions (PACs) (time frame: Maximum of 2 weeks). The study lists 2 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 9 Mar 2026.