What precautions should be taken for patients with hypertension undergoing a Lexiscan (regadenoson) test?

Precautions for Hypertensive Patients Undergoing Lexiscan (Regadenoson) Testing

Patients with hypertension should be carefully screened for contraindications before undergoing a Lexiscan test, with close monitoring of blood pressure during and after the procedure due to potential significant hemodynamic changes. 1

Contraindications and Screening

• Absolute contraindications for regadenoson use:

  • Second- or third-degree AV block without a functioning pacemaker
  • Sinus node dysfunction without a functioning pacemaker 1
  • Symptoms or signs of acute myocardial ischemia (unstable angina or cardiovascular instability) 1

• Pre-test assessment should include:

  • Blood pressure measurement to identify uncontrolled hypertension
  • Review of medications, particularly beta-blockers which may affect heart rate response
  • ECG to identify pre-existing conduction abnormalities
  • Assessment for symptoms of acute coronary syndrome 1, 2

Blood Pressure Considerations

• For patients with hypertension:

  • Ensure blood pressure is adequately controlled before the test
  • Be aware that regadenoson can cause significant hemodynamic changes:
    • Initial increase in systolic blood pressure
    • Decrease in diastolic blood pressure 3, 4
    • Potential for clinically significant increases in blood pressure, particularly in patients with history of hypertension 1

• Blood pressure monitoring:

  • Measure baseline BP before administration
  • Monitor BP during the test and for at least 30 minutes after
  • Have emergency equipment readily available for severe hypertensive responses 1

Special Precautions for Hypertensive Patients

• For patients with uncontrolled hypertension:

  • Consider postponing the test until BP is better controlled
  • If proceeding, ensure closer monitoring during and after the test
  • Be prepared for potential exaggerated BP responses 1

• For patients with hypertension and comorbidities:

  • Patients with stenotic valvular heart disease, pericarditis, pericardial effusions, or carotid artery disease may be at higher risk for serious hypotension 1
  • Patients with autonomic dysfunction may have unpredictable BP responses 1

Management During Testing

• During the procedure:

  • Have cardiac resuscitation equipment and trained staff immediately available
  • Monitor for signs of significant hypotension or hypertension
  • Be prepared to treat severe hypertensive responses 1

• Common side effects to anticipate:

  • Dyspnea (most common, occurring in up to 70% of patients)
  • Headache
  • Flushing
  • Chest discomfort
  • Dizziness 3, 4

• Serious adverse events to watch for:

  • Advanced heart block (rare but reported)
  • Asystole (rare but reported)
  • Significant hypertensive responses 2

Post-Test Monitoring

• Continue BP monitoring for at least 30 minutes after the test
• Ensure BP returns to baseline before discharge
• Consider longer monitoring for patients with poorly controlled hypertension
• Have aminophylline available to reverse severe and persistent adverse reactions to regadenoson 1

Medication Considerations

• Prior to testing:
  • Withhold dipyridamole for at least two days if possible 1
  • Avoid methylxanthines (caffeine, aminophylline, theophylline) which interfere with regadenoson activity 1
  • Note that patients on beta-blockers may have a blunted heart rate response 5

By following these precautions, regadenoson stress testing can be performed safely in most hypertensive patients, but careful patient selection and monitoring are essential to minimize risks.