Impact of Left Heart Disease Risk Factors on Outcomes in Pulmonary Arterial Hypertension Therapy

Abstract

BackgroundCurrent guidelines recommend initial monotherapy for pulmonary arterial hypertension (PAH) with ‘cardiopulmonary comorbidities’, despite limited available evidence to guide management. Research QuestionDo left heart disease (LHD) risk factors have an impact on treatment response and influence applicability of risk assessment in a real-world cohort of PAH patients? Study Design and MethodsThe AMBITION trial criteria was used to define the phenotype of PAH patients with risk factors for LHD. Treatment strategy, functional outcome, long term survival and risk discrimination were compared with a reference PAH cohort using the PHSANZ registry. Results487 incident PAH patients diagnosed between 2011-2020 were included. Of these, 103 (21.1%) fulfilled the definition of PAH with LHD risk factors with 384 (78.9%) remaining as reference group. PAH with LHD risk factors were older (66±13 vs. 58±19years, p<0.001), had lower pulmonary vascular resistance (393±266 vs 708±391dynes/sec/cm-5, p=0.031) and worse 6-minute walk distance (286±130 vs. 327±136m, p=0.005) at diagnosis. PAH with LHD risk factors were less likely to receive less initial combination therapy (27% vs. 44%, p=0.02). Changes in 6-minute walk distance at 12-months were similar in both groups, 43±77 in PAH with LHD risk factors and 50±90m in reference group (p=0.5), including when stratified by initial treatment strategy (monotherapy: 40±81 vs. 38±95m p=0.87 and combination therapy: 53±78 vs. 64±106m, p=0.511; PAH with LHD risk factors vs. reference PAH). Functional class improvements were also similar in both groups. REVEAL 2.0 risk score effectively discriminated risk in both populations (C-statistic=0.756 for PAH with LHD risk factors and C-statistic=0.750 for reference PAH). There was no difference in survival between the two groups (log-rank test p=0.29). InterpretationIn a real-word cohort, PAH patients with LHD risk factors were less likely to be exposed to initial combination therapy. Nevertheless, selected PAH patients with LHD risk factors who were treated with initial combination therapy derived similar functional response compared to reference group. Further studies are needed to phenotype PAH patients with cardiopulmonary comorbidities who may benefit from initial combination therapy.