COMPASS-3 is a prospective, multi-center study which uses a targeted 6-minute walk test distance (6-MWD) threshold approach to guide bosentan-based combinational therapy and assess the utility of cardiac MRI (cMRI) compared with right heart catheterization (RHC) and echocardiography to evaluate prognosis in pulmonary arterial hypertension (PAH).
One hundred therapy-naεve PAH patients with baseline 6-MWD 150–360m will receive bosentan for 4 months. Those not reaching a 6-MWD >380 m will have have sildenafil added (20 mg tid) while the others will continue on bosentan monotherapy (3 months for each group). Evaluations are performed at baseline, 16 weeks and 28 weeks. At this time, 53 patients have completed a Week 16 follow-up visit and these data are reported.
The mean±SD age was 56±15 years and 83% were female. We found improvements in NT-pro-BNP, WHO functional class and hemodynamics from baseline (Table). Forty-seven percent of patients experienced ≥10% improvement in 6-MWD from baseline and 40% had ≥50m improvement. Only 15% achieved the pre-specified 380m threshold and continued bosentan monotherapy. Results on all 100 patients will be reported at the meeting.
Bosentan monotherapy enabled improvements in hemodynamics, functional class and 6-MWD at 16 weeks.
Despite the improvement seen with bosentan monotherapy, it appears that a combination approach (bosentan plus sildenafil) will be needed for the majority of PAH patients in order to potentially achieve the >380m threshold. Analysis of the entire study group (100 patients) will be available at the time of the meeting and should reveal if this combination was successful in reaching the 380m goal.
Francisco Soto, Grant monies (from industry related sources) Fernando Torres: Research grant-Pfizer. Srinivas Murali: Research support-Actelion, Gilead.; Consultant fee, speaker bureau, advisory committee, etc. Francisco Soto: Advisory board/consultant-Actelion. Fernando Torres: Speaker, Scientific Advisory Board-Actelion; Speaker-Pfizer. Devendra Amin: Speaker-Actelion, Glasko Smith Kline, Bio-Merieux. Himanshu Gupta: consultant-Actelion. Myung Park: Advisory board/consultant-Actelion, Gilead, United Therapeutics. Srinivas Murali: consultant and speaker's bureau-Actelion, Gilead. Raymond Benza: Honoraria-Actelion, Encysive, Pfizer.; No Product/Research Disclosure Information