Is adenosine safe for performing a nuclear stress test in patients with non-sustained ventricular tachycardia (VT)?

From the Guidelines

Adenosine can be used with caution for nuclear stress testing in patients with a history of non-sustained ventricular tachycardia (NSVT), but it requires careful consideration of individual risk factors. The standard adenosine protocol typically involves administration of 140 mcg/kg/min intravenously over 4-6 minutes, with radiotracer injection at the midpoint of infusion. Adenosine is generally preferred over exercise stress in patients with arrhythmias because it has a very short half-life (less than 10 seconds) and any adverse effects resolve quickly after discontinuation 1. However, patients with NSVT should be monitored closely during the test with continuous ECG recording and immediate availability of resuscitation equipment. The test should be performed in a setting where advanced cardiac life support is readily available.

Some key points to consider when using adenosine in patients with NSVT include:

• The potential for adenosine to trigger arrhythmias, although this is rare 1
• The importance of individualizing the decision to use adenosine based on the frequency and severity of the patient's NSVT episodes, underlying cardiac disease, and overall clinical stability 1
• The need for careful monitoring and availability of resuscitation equipment during the test
• The potential benefits of using alternative vasodilators like regadenoson (0.4 mg IV bolus) in high-risk patients, which has more selective A2A receptor activity and potentially fewer arrhythmic effects.

According to the most recent guidelines, patients with NSVT at rest that is suppressed with exercise and who have no evidence of structural heart disease, molecular/genetic disorders, or transient abnormalities at the time of evaluation can be cleared for competitive athletics without limitations 1. However, the use of adenosine in these patients should still be approached with caution and careful consideration of individual risk factors.

From the Research

Safety of Adenosine in Nuclear Stress Test for Patients with Non-Sustained VT

• The use of adenosine in patients with non-sustained ventricular tachycardia (NSVT) has been studied in various contexts, including its diagnostic and therapeutic value in arrhythmias 2.
• Adenosine is known to produce transient heart block and can terminate supraventricular tachycardias, but it may also induce non-sustained polymorphic ventricular tachycardia in some cases 2.
• The prognosis of NSVT in patients with normal hearts is generally benign, and treatment is often targeted towards symptoms rather than the arrhythmia itself 3.
• In patients with structural heart disease or other underlying conditions, NSVT may carry a higher risk of adverse outcomes, and management should focus on treating the underlying condition 4.

Adenosine-Induced Ventricular Tachycardia

• Adenosine-sensitive ventricular tachycardia has been identified as a distinct entity, often originating from discrete sites in the heart, such as the pulmonary infundibulum 5.
• Catheter ablation techniques have been shown to be effective in treating adenosine-sensitive ventricular tachycardia, with good long-term outcomes 5.
• The occurrence of NSVT in patients with hypertrophic cardiomyopathy may carry prognostic significance, but the independent predictive value of NSVT in this context is still debated 6.

Clinical Implications

• The safety of adenosine in nuclear stress tests for patients with NSVT depends on individual patient characteristics, including the presence of underlying heart disease and the specific type of ventricular tachycardia 2, 3, 4.
• Clinicians should carefully evaluate each patient's risk profile and consider the potential benefits and risks of adenosine use in this context 2, 3, 4.