From the Guidelines
Patients with heart block can undergo stress tests, but caution is needed and modifications may be required, with the most recent guidelines suggesting that vasodilator pharmacological stress imaging is contraindicated in significant arrhythmias, including second- or third-degree atrioventricular block 1. The type and severity of heart block will determine if a stress test is safe and appropriate.
- For patients with first-degree or Mobitz I second-degree heart block, standard stress tests can usually be performed safely under close monitoring.
- However, for those with more advanced heart block (Mobitz II second-degree or third-degree), a pharmacological stress test using medications like dobutamine may be preferred over exercise stress testing, as vasodilator pharmacological stress imaging is contraindicated in these cases 1. Before proceeding with any stress test, the patient should have a thorough cardiac evaluation, including an ECG and possibly a 24-hour Holter monitor.
- The cardiologist may need to temporarily adjust medications or pacing settings in patients with pacemakers. During the test, continuous ECG monitoring is essential.
- The test should be immediately stopped if the patient develops symptoms like dizziness, fainting, or chest pain, or if there are concerning changes in heart rhythm or blood pressure. The reason for caution is that stress tests increase heart rate and cardiac demand, which could potentially exacerbate conduction abnormalities in patients with heart block.
- However, when performed under proper supervision, stress tests can provide valuable information about cardiac function and ischemia in these patients, as stated in the 2024 AHA/ACC/ACS/ASNC/HRS/SCA/SCCT/SCMR/SVM guideline for perioperative cardiovascular management for noncardiac surgery 1.
From the FDA Drug Label
• Second- or third-degree AV block (except in patients with a functioning artificial pacemaker) ( 4) • Sinoatrial (SA) and Atrioventricular (AV) Nodal Block. First-, second- or third-degree AV block, or sinus bradycardia can occur. Discontinue adenosine injection if patient develops persistent or symptomatic high-grade AV block ( 5-5. 2)
A patient with a heart block should not undergo a stress test using adenosine injection unless they have a functioning artificial pacemaker. The presence of a heart block, specifically second- or third-degree AV block, is a contraindication for the use of adenosine injection. 2
From the Research
Patient Eligibility for Stress Test
- A patient with a heart block can undergo a stress test, but it is considered a relative contraindication 3.
- The decision to perform a stress test on a patient with a heart block should be made on a case-by-case basis, weighing the benefits and risks of the test 3.
- Patients with complete heart block can undergo exercise stress testing, and the benefits of testing may outweigh the risks 3.
Types of Stress Tests
- Exercise-based stress tests are available, and different protocols can be used depending on the patient's clinical status 4, 5.
- Pharmacological stress tests can be used for patients who are incapable of achieving 5 metabolic equivalent units (METs) of exercise 4.
- Adenosine pharmacologic stress testing can be safely performed in patients with first-degree atrioventricular block, even in the presence of atrioventricular blocking medications 6.
Risks and Complications
- Although stress testing is generally a safe procedure, complications may occur, including atrioventricular dissociation and syncope 7.
- The risk of complications during exercise stress testing is minimal, with a <1% chance of causing heart block 7.
- Patients with baseline first-degree AV block may experience second- or third-degree AV block during adenosine stress testing, but these episodes are usually short-duration and do not require specific treatment 6.