What are the contraindications to a nuclear stress test?

Contraindications to Nuclear Stress Testing

Nuclear stress testing is contraindicated in patients with high-risk unstable angina, complicated acute coronary syndrome (ACS), or acute myocardial infarction (AMI) within the past 2 days. 1

General Contraindications

Cardiac Conditions

• High-risk unstable angina, complicated ACS or AMI (<2 days) 1
• Significant arrhythmias (e.g., ventricular tachycardia, second- or third-degree atrioventricular block) or sinus bradycardia <45 bpm 1
• Significant hypotension (systolic blood pressure <90 mm Hg) 1
• Severe systemic arterial hypertension (≥200/110 mm Hg) 1
• Hemodynamically significant left ventricular outflow tract obstruction 1
• Uncontrolled heart failure 1

Respiratory Conditions

• Known or suspected bronchoconstrictive or bronchospastic disease (contraindication to vasodilator stress agents) 1
• Respiratory failure 1
• Severe COPD, acute pulmonary emboli, severe pulmonary hypertension 1

Medication-Related Contraindications

• Recent use of dipyridamole or dipyridamole-containing medications 1
• Use of methylxanthines (e.g., aminophylline, caffeine) within 12 hours before the test 1

Acute Conditions

• Acute illness (e.g., acute pulmonary embolism, acute myocarditis/pericarditis, acute aortic dissection) 1

Specific Contraindications Based on Stress Method

Exercise Stress Contraindications (when exercise is the stressor)

• Inability to achieve ≥5 METs or unsafe to exercise 1, 2
• Abnormal ST changes on resting ECG, digoxin use, left bundle branch block, Wolff-Parkinson-White pattern, ventricular paced rhythm (unless test is performed to establish exercise capacity only) 1
• Severe symptomatic aortic stenosis 1

Pharmacologic Stress Contraindications

• For adenosine/regadenoson: known hypersensitivity to these agents 1
• For adenosine: pre-existing significant conduction system disease (may lead to persistent AV block requiring pacemaker implantation) 3

Special Populations

Pregnancy and Breastfeeding

• Nuclear stress testing should generally be avoided during pregnancy due to radiation exposure to the fetus 1
• If imaging is necessary during pregnancy, the risks and benefits should be discussed with the patient 1

Obese Patients

• Very obese patients exceeding weight-bearing limits of SPECT imaging tables (often 300 lb/135 kg) may require planar scintigraphy instead 1

Clinical Considerations and Alternatives

• When nuclear stress testing is contraindicated, consider alternative non-radiation testing modalities such as stress echocardiography or exercise ECG (if appropriate) 4
• For patients with left bundle branch block or ventricular-paced rhythm, nuclear stress testing remains the preferred non-invasive evaluation method 4
• In patients with reduced renal function, the risks of contrast agents must be weighed against the benefits of the test 1

Pitfalls to Avoid

• Failing to screen for caffeine intake before vasodilator stress tests, which can lead to false-negative results 1
• Overlooking medication interactions, particularly with dipyridamole-containing medications 1
• Performing nuclear stress tests in patients with active bronchospastic disease when using vasodilator agents, which can precipitate severe bronchospasm 1
• Neglecting to consider radiation exposure in younger patients, for whom the projected cancer risk is elevated 1

When nuclear stress testing is contraindicated, the American Heart Association recommends following the principle of As Low as Reasonably Achievable (ALARA) for radiation exposure and considering alternative non-radiation testing modalities when appropriate 1.