Observational Study of Cardiac Arrhythmias During Treatment With BTK Inhibitors or Venetoclax


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Bruton s tyrosine kinase inhibitors (BTKi) are used to treat a form of leukemia. But taking BTKi can also increase a person s risk of developing an abnormal heart rhythm. This can cause sudden death. In this natural history study, researchers want to learn how BTKi affects the heart.


To identify and monitor the effects of BTKi on the heart.


People aged 18 and older currently receiving or planning to receive BTKi or venetoclax.


Participants who have not yet started BTKi will have 2 required clinic visits: 1 before they start taking BTKi, and 1 about 6 months later. Participants who are already taking BTKi will have 1 required visit.

Participants will undergo multiple tests:

A physical exam, including collection of blood and saliva.

A test that measures heart activity via stickers placed on the chest.

A test that uses sound waves to capture images of the heart.

An exercise stress test that monitors heart activity and blood pressure while the participant works on a treadmill or stationary bike. Sound wave images of the heart may also be taken while the participant exercises.

Stress magnetic resonance imaging (MRI) may be done in place of an exercise test. Participants will lie on a table that slides into a tube. They will be given drugs to stress the heart while images are taken.

Participants may wear a device to monitor their heart at home.

Participants may have repeat visits if they develop heart symptoms or if they need to stop taking BTKi. They will have follow-up phone calls each year for up to 3 years.

Study Overview

Start Date
March 1, 2023
Completion Date
April 8, 2027
Date Posted
February 13, 2023
Accepts Healthy Volunteers?


Full Address
National Institutes of Health Clinical Center
Bethesda, Maryland 20892, United States


Study Population
Sample size of 135 subjects including men and women over 18 years old followed at the NIH Clinical Center who are either about to start a BTKi (Cohort A) or venetoclax (Cohort C) as well as those already taking BTKi (Cohort B)
Minimum Age (years)
Maximum Age (years)
Eligibility Criteria

To be eligible to participate in this study, an individual must meet all of the following criteria:

Currently receiving or planning to receive a BTKi or venetoclax.
Male or female, aged 18 or older
Stated willingness to comply with all study procedures and availability for the duration of the study
Ability of subject to understand and the willingness to sign a written informed consent document


An individual who meets any of the following criteria will be excluded from participation in this study:

Any acute cardiac condition including myocardial infarction or decompensated heart failure within the past 3 months
Pregnancy or lactation- use of BTK inhibitors is contraindicated in pregnant or nursing individuals.

Study Contact Info

Study Contact Name
Shellin Jose; Clare C Sun, M.D.
Study Contact Phone

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Other Details

FDA Regulated Drug?
FDA Regulated Device?
Detailed Description
Study Description:

Pharmacologic therapy with BTK inhibitors (BTKi) is associated with an increased risk of cardiac arrhythmias which can lead to sudden death. There is currently no standard for cardiac screening or monitoring patients on BTKi. We hypothesize that thorough and routine comprehensive cardiac evaluations prior to starting therapy with BTKi and repeated during therapy with BTKi will result in earlier identification of cardiac arrhythmias with the goal of minimizing associated morbidity and mortality. In addition, venetoclax, a different standard therapy for chronic lymphocytic leukemia, has not been associated with increased cardiac adverse events and could serve as a control group.


Primary objective: Identify, monitor, and analyze the arrhythmogenic effects of BTKi as well as sudden death

Secondary objective: Assess the utility of different cardiac tests for identifying and monitoring cardiac arrhythmias in patients receiving BTKi or venetoclax

Exploratory objective: To examine the relationship between the development of cardiac arrhythmias in patients on BTKi as it relates to other variables


Primary endpoint:

-A composite endpoint of clinically significant cardiac arrhythmias and sudden death in patients starting a BTKi (Cohort A) and in patients already receiving BTKi (Cohort B).

Secondary endpoints:

Detection of arrhythmias on devices (rest/stress EKG, ambulatory EKG monitor, KardiaMobile)
Arrhythmia (treatment emergent or worsening) in patients on BTKi
Sudden death in patients on BTKi
A composite endpoint of clinically significant cardiac arrhythmias and sudden death in patients starting venetoclax
Difference in cardiac arrhythmias and sudden death between different BTKi groups (e.g., ibrutinib vs. non-ibrutinib group)
Difference in cardiac arrhythmias and sudden death between BTKi and venetoclax groups

Exploratory endpoints:

Pharmacokinetic levels of BTKi
Duration of BTKi exposure
Cumulative BTKi dose
Genetic variants
Cardiac structural remodeling
Medical comorbidities
Concomitant medications
Substance use
Identify risk factors or biomarkers for arrhythmia
NCTid (if applicable)