Will a patient with multiple valvular regurgitations, aortic dilatation, and moderate aortic regurgitation experience complications during a Lexiscan (regadenoson) test?

Safety of Lexiscan (Regadenoson) in a Patient with Multiple Valvular Regurgitations and Aortic Dilatation

Patients with moderate aortic regurgitation, multiple valvular regurgitations, and aortic dilatation can safely undergo a Lexiscan (regadenoson) stress test, but require close monitoring due to potential risks of hypotension and arrhythmias. 1

Risks Associated with Regadenoson in Valvular Disease

• Regadenoson is a pharmacologic stress agent indicated for radionuclide myocardial perfusion imaging in patients unable to undergo adequate exercise stress 1
• The FDA label for regadenoson specifically mentions that patients with stenotic valvular heart disease may be at higher risk for serious hypotension during administration 1
• While regadenoson can cause hypotension due to arterial vasodilation, valvular regurgitation itself is not listed as a specific contraindication 1

Specific Concerns for This Patient

• Moderate aortic regurgitation (AR) is classified as Stage B progressive AR according to ACC/AHA guidelines, characterized by:

  • Jet width 25%-64% of LVOT
  • Vena contracta 0.3-0.6 cm
  • Regurgitant fraction 30%-49%
  • Normal LV function or mild LV dilation 2

• Aortic dilatation commonly coexists with AR and may share pathophysiological mechanisms:

  • The combination can lead to increased hemodynamic stress on the aortic wall 3, 4
  • Patients with aortic dilatation and AR require careful monitoring of both conditions 2

Monitoring Recommendations During Lexiscan

• Cardiac monitoring: Continuous ECG monitoring is essential as regadenoson can cause:

  • First, second, or third-degree AV block
  • Sinus bradycardia
  • Atrial fibrillation or flutter with rapid ventricular response 1

• Blood pressure monitoring: Close monitoring is critical as:

  • Decreased systolic blood pressure (>35 mmHg) was observed in 7% of patients
  • Decreased diastolic blood pressure (>25 mmHg) was observed in 4% of patients 1
  • Patients with valvular disease may be at higher risk for hypotension 1

• Resuscitation equipment: Must be immediately available due to potential for:

  • Myocardial ischemia
  • Ventricular arrhythmias
  • Cardiac arrest (though rare) 1

Precautions for Multiple Valve Disease

• Multiple valve disease creates complex hemodynamic interactions:

  • Combined regurgitant lesions can lead to more severe LV volume overload than single lesions 2
  • The presence of "leaky valves" can affect cardiac output and response to vasodilator stress 2

• Echocardiographic assessment before the test is valuable to:

  • Confirm current severity of valvular regurgitations
  • Assess LV size and function
  • Evaluate aortic dimensions 2

Risk Mitigation Strategies

• Consider having aminophylline available to reverse effects of regadenoson if serious adverse reactions occur 1
• Ensure proper hydration status before the test to minimize hypotension risk 1
• Avoid caffeine and methylxanthine-containing products for at least 12 hours before the test 1
• Consider lower-level exercise stress testing as an alternative if appropriate for the patient's condition 2

Conclusion

While there are potential risks associated with regadenoson administration in patients with valvular disease and aortic dilatation, the test can be performed safely with appropriate precautions and monitoring. The benefits of obtaining diagnostic information about coronary perfusion likely outweigh the risks in most cases, provided proper safety measures are implemented.