Which of the following is the best initial treatment for a patient with WHO FC II symptoms of PAH?

For a patient exhibiting World Health Organization Functional Class II (WHO FC II) symptoms of pulmonary arterial hypertension (PAH), the best initial treatment is the combination of sildenafil and macitentan.

Sildenafil is a phosphodiesterase-5 (PDE-5) inhibitor which works by promoting vasodilation in the pulmonary arterial system, thereby reducing pulmonary artery pressure and improving exercise capacity. Macitentan, an endothelin receptor antagonist, complements this treatment by further dilating pulmonary and systemic arterial vascular beds and improving hemodynamics in patients with PAH.

The combination of sildenafil and macitentan has been studied and demonstrated to be effective for patients with WHO FC II symptoms, as it addresses both endothelial dysfunction and promotes better pulmonary hemodynamics. This dual mechanism can enhance overall outcomes and improve the quality of life for these patients.

In contrast, the other options may include drugs that are more appropriate for higher functional classes or present more complex mechanisms of action that may not be suitable for initial therapy in WHO FC II patients. While these combinations may have their own therapeutic benefits, they might not be as effective or necessary in the early treatment stages for someone with mild symptoms.