F-2 | Role of mean systemic to pulmonary artery pressure ratio in balloon pulmonary angioplasty and chronic thromboembolic pulmonary hypertension

Reduced mean systemic to pulmonary artery pressure ratio (MAP/PAP), a marker of global cardiac dysfunction and adverse outcomes, is unstudied in balloon pulmonary angioplasty (BPA) and chronic thromboembolic pulmonary hypertension (CTEPH). A total of 65 subjects underwent 6 BPA sessions at UC San Diego. Pre- and post-BPA MAP/PAP, 6-minute walking distance (6MWD) and WHO functional class (FC) were measured. T-test, ANOVA, chi-square, and receiver-operator characteristic (ROC) curve tests were used. P-value <0.05 was significant. "Responders" improved from WHO FC III/IV to I/II after BPA. "Non-responders" had unchanged WHO FC III/IV after BPA. Overall mean MAP/PAP improved from 2.2±0.69 to 2.7±0.92 after BPA (p<0.001). MAP/PAP <2.5 was associated with FC III/IV (area 0.698; p=0.002), more frequent FC III/IV symptoms (60.1% vs 32.7%, p<0.001) and shorter 6MWD (410±117 vs 481±127 meters; p=0.003) versus MAP/PAP ≥2.5. Stepwise reduction of mean MAP/PAP was observed with higher WHO FC (I/II/III/IV: 3.2±1.13, 2.7±0.83, 2.3±0.64, 1.9±0.22; p<0.001) (Figure A). MAP/PAP in BPA "responders" vs "non-responders" was similar at baseline (2.2±0.67 vs 2.0±0.51; p=0.279), but higher after BPA (2.8±0.81 vs 2.3±0.48; p=0.047), respectively. MAP/PAP increased to a greater degree after BPA among "responders" (2.2±0.67 to 2.8±0.81; p=0.006) than "non-responders" (2.0±0.51 to 2.3±0.48, p=0.061) (Figure B). Higher MAP/PAP in subjects undergoing BPA is associated with superior physical function. MAP/PAP increased stepwise across treatment sessions in the overall BPA cohort and may help identify "responders" to BPA therapy.