Group 1 pulmonary arterial hypertension — initial therapy choice: ERA, PDE5i, or prostacyclin?

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Per ESC/ERS 2022 PAH Guidelines — this question is excellently framed. **Risk Stratification First (ESCRHS 2022):** This patient's risk profile: - WHO FC II-III (intermediate) - 6MWD 340m (low-intermediate) - mPAP 48, PVR 8 (high) - TAPSE 14mm (low, RV dysfunction) - No vasoreactivity → NOT a candidate for calcium channel blockers Risk score: **INTERMEDIATE-HIGH risk** (based on REVEAL 2.0 or simplified ESC risk score) **ESC/ERS 2022 Initial Combination Therapy Recommendation:** For NEWLY DIAGNOSED PAH without acute vasoreactivity: - **WHO FC II:** Initial dual combination therapy — ERA + PDE5i (Class I, Level A). AMBITION trial showed superior outcomes with ambrisentan + tadalafil vs monotherapy. - **WHO FC III-IV:** Initial dual or triple combination (ERA + PDE5i ± prostacyclin analog). TRITON trial supports upfront triple for high-risk patients. **For this patient (FC II-III):** → **Upfront dual combination: Ambrisentan (ERA) + Tadalafil (PDE5i)** is the recommended starting therapy. NOT monotherapy. **Drug Details:** - ERA options: Ambrisentan 10mg OD or Macitentan 10mg OD (macitentan preferred for organ protection, SERAPHIN trial) - PDE5i options: Tadalafil 40mg OD (preferred over sildenafil for once-daily dosing) - Prostacyclin (Selexipag, Epoprostenol): Add-on for high-risk or FC deterioration on dual therapy **Evidence for FC II combination therapy:** AMBITION trial — combination reduced risk of clinical failure by 50% vs monotherapy in FC II patients. **Monitoring:** Reassess at 3-4 months with 6MWD, NTproBNP, echo parameters. If inadequate response (intermediate-high risk persists) — add selexipag (oral prostacyclin pathway agent) per GRIPHON trial data.