What is Lexiscan (Regadenoson) cardiolyte?

From the Guidelines

Lexiscan (Regadenoson) is a pharmacological stress agent used in conjunction with Cardiolyte (technetium-99m sestamibi) for nuclear stress tests to evaluate heart function and blood flow, particularly for diagnosing coronary artery disease. This procedure is particularly useful for patients who cannot perform physical exercise stress tests due to physical limitations. The test involves injecting Lexiscan to simulate exercise stress by dilating coronary arteries, followed by the injection of Cardiolyte, a radioactive tracer that shows blood flow to the heart muscle [ 1 ]. A special camera then captures images of the heart, showing areas with normal blood flow versus areas with reduced flow that might indicate blockages.

The choice of Lexiscan for stress testing is supported by its favorable side-effect profile, especially in patients with bronchospasm, compared to other pharmacological stress agents like adenosine and dipyridamole [ 1 ]. The diagnostic accuracy of nuclear myocardial perfusion imaging (MPI) with Lexiscan has been studied extensively, showing high sensitivity and specificity for detecting obstructive coronary artery disease (CAD) [ 1 ].

Key points about Lexiscan Cardiolyte include:

• It is used for diagnosing coronary artery disease in patients who cannot perform exercise stress tests.
• Lexiscan (regadenoson) is administered as a bolus injection to simulate exercise stress.
• Cardiolyte (technetium-99m sestamibi) is used as a radioactive tracer to show blood flow to the heart muscle.
• The test provides valuable information about coronary circulation and heart function to guide treatment decisions for heart conditions [ 1 ].
• Lexiscan has a more favorable side-effect profile compared to other pharmacological stress agents, making it a preferred choice for certain patients [ 1 ].

From the FDA Drug Label

LEXISCAN is a sterile, nonpyrogenic solution for intravenous injection. The solution is clear and colorless. Each 1 mL in the 5 mL pre-filled syringe contains 0.084 mg of regadenoson monohydrate, corresponding to 0.08 mg regadenoson on an anhydrous basis, 10.9 mg dibasic sodium phosphate dihydrate or 8.7 mg dibasic sodium phosphate anhydrous, 5. 4 mg monobasic sodium phosphate monohydrate, 150 mg propylene glycol, 1 mg edetate disodium dihydrate, and Water for Injection, with pH between 6.3 and 7.7.

• Lexiscan (Regadenoson) cardiolyte is a sterile, nonpyrogenic solution for intravenous injection, containing regadenoson and other ingredients such as dibasic sodium phosphate, monobasic sodium phosphate, propylene glycol, and edetate disodium dihydrate 2 2.
• The main active ingredient is regadenoson, an A2A adenosine receptor agonist that acts as a coronary vasodilator.

From the Research

Definition and Mechanism of Action

• Lexiscan (Regadenoson) is a specific adenosine receptor agonist used in pharmacologic stress testing due to its coronary vasodilatory effects 3.
• It is a highly subtype-selective, potent, low-affinity A2A adenosine receptor agonist that achieves maximum coronary hyperemia equivalent to adenosine 4.
• Regadenoson causes a rapid increase in coronary blood flow, which is sustained for a short duration, making it suitable for radionuclide myocardial perfusion imaging 5.

Clinical Applications and Safety

• Regadenoson is approved for use as a pharmacologic stress agent for radionuclide myocardial perfusion imaging in patients unable to undergo adequate exercise stress 5.
• It is generally well-tolerated, with most adverse events beginning soon after administration and resolving within approximately 15 minutes 5.
• The clinical adverse effect profile of regadenoson appears to be favorable, particularly with respect to dreaded atrioventricular conduction disturbances and bronchospasm 4.
• Regadenoson can be safely used for cardiac MRI stress tests, with no severe adverse effects observed in a study of 120 patients 6.

Comparison with Adenosine

• Regadenoson has a several-fold shorter duration of action compared to binodenoson, another A2A adenosine receptor agonist 4.
• Regadenoson, compared with adenosine, was associated with a faster and greater peak increase in heart rate, but a slower return to baseline 5.
• The effects of regadenoson on hemodynamics, ventricular volumes, and ejection fractions are significant and prolonged, similar to adenosine 7.