American Board of Internal Medicine (ABIM) Certification Practice Exam

In patients without a positive response to vasoreactivity testing, what should be avoided in pulmonary arterial hypertension treatment?

1. Calcium channel blockers

2. Phosphodiesterase-5 inhibitors

3. Endothelin receptor antagonists

4. Beta-agonists

The correct answer is: Calcium channel blockers

In the context of treating pulmonary arterial hypertension (PAH), the importance of vasoreactivity testing cannot be overstated. This test identifies patients who demonstrate a significant response to vasodilators, which indicates that they may benefit from treatment with calcium channel blockers. In patients who do not show a positive response to this testing, the use of calcium channel blockers should be avoided. Calcium channel blockers can lead to significant side effects and may not provide any therapeutic benefit in patients who do not respond to vasodilators, where the underlying pathophysiology does not favor a vasodilatory approach. In such cases, maintaining a treatment regimen that includes more appropriate therapies, such as phosphodiesterase-5 inhibitors or endothelin receptor antagonists, is crucial. These medications target different pathways involved in PAH and are more suitable for managing patients who do not exhibit vasoreactivity. Phosphodiesterase-5 inhibitors and endothelin receptor antagonists serve to enhance vasodilation and reduce pulmonary artery pressure through different mechanisms compared to calcium channel blockers, making them the preferred choices in patients without a positive vasoreactivity response. Thus, avoiding calcium channel blockers is essential in the management of PAH for those not responsive to prior testing, contributing