Our findings contribute to the growing body of evidence supporting the superiority of combination therapy over monotherapy in CTD-PAH.[21, 22, 23, 24, 25] While previous studies have demonstrated the benefits of initial combination therapy with an ERA and a PDE-5 inhibitor,[2] our study provides valuable real-world data directly comparing the effectiveness of tadalafil and sildenafil in this context. Here, PDE5A is linked to pulmonary arterial hypertension.