A physician-validated, board-style question from the Active Transport QBank. Try it, then check the reasoning for every option.
A 62-year-old man with history of heart failure with preserved ejection fraction (HFpEF) and COPD presents to his cardiologist for a right heart catheterization procedure after a recent echocardiogram revealed pulmonary artery pressure (PAP) of 55 mmHg. Intraoperative administration of intravenous adenosine causes the PAP to decrease to 35 mmHg. What pharmacological therapy is most likely to provide long-term benefit for this patient?
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A
EpoprostenolIncorrect. Epoprostenol (IV prostacyclin) is reserved for severe PAH non-responsive to vasodilator challenge or for WHO functional class IV disease.
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B
AdenosineIncorrect. Adenosine has too short a half-life (seconds) for chronic therapy — it is used only as the diagnostic vasoreactivity test agent.
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C
BosentanIncorrect. Bosentan, an endothelin receptor antagonist, is used in non-vasoreactive PAH or as add-on therapy, not as first-line for a vasoreactive responder.
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D
AmlodipineCorrect. A positive vasoreactivity test (PAP drop with acute adenosine) identifies a patient who will benefit from chronic high-dose calcium channel blocker therapy like amlodipine.
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E
SildenafilIncorrect. Sildenafil, a PDE-5 inhibitor, is approved for non-vasoreactive pulmonary arterial hypertension; in a vasoreactivity-positive patient, high-dose calcium channel blockers are preferred first-line.
↑ Tap an answer to reveal the reasoning
Answer: D. Right heart catheterization showing a significant drop in pulmonary artery pressure after vasodilator challenge (here, adenosine: PAP 55 → 35 mmHg, a >20% reduction to <40 mmHg) identifies a patient with vasoreactive pulmonary arterial hypertension (PAH). This subgroup — roughly 10% of idiopathic PAH — derives long-term benefit from high-dose calcium channel blockers (specifically amlodipine, nifedipine, or diltiazem). The acute vasoreactivity test predicts which patients will respond to chronic CCB therapy.
For non-vasoreactive PAH, advanced agents are used: endothelin receptor antagonists (bosentan, ambrisentan), PDE-5 inhibitors (sildenafil, tadalafil), guanylate cyclase stimulators (riociguat), or prostacyclin analogs (epoprostenol). Epoprostenol and bosentan are reserved for non-responders or more advanced disease. Adenosine is only used as the acute test agent, not chronically (very short half-life). Note: the patient's HFpEF complicates the picture slightly, but the vasoreactive response identifies amlodipine as appropriate.
**Why each option:**
**A.** Epoprostenol (IV prostacyclin) is reserved for severe PAH non-responsive to vasodilator challenge or for WHO functional class IV disease.
**B.** Adenosine has too short a half-life (seconds) for chronic therapy — it is used only as the diagnostic vasoreactivity test agent.
**C.** Bosentan, an endothelin receptor antagonist, is used in non-vasoreactive PAH or as add-on therapy, not as first-line for a vasoreactive responder.
**D.** Correct. A positive vasoreactivity test (PAP drop with acute adenosine) identifies a patient who will benefit from chronic high-dose calcium channel blocker therapy like amlodipine.