Current treatment guidelines recommend the use of warfarin in patients with idiopathic pulmonary arterial hypertension (IPAH), despite limited evidence on its efficacy. Investigators in a new study published in Circulation have reported that warfarin treatment does not improve survival in patients with IPAH, and is associated with poorer survival outcomes in patients with systemic sclerosis pulmonary arterial hypertension (SSc-PAH).

Patients initiated on warfarin after enrolment into the multicentre REVEAL registry were matched 1:1 using a nested design to patients who had never received warfarin within each aetiological group (IPAH and SSc-PAH). Survival analyses were performed with or without risk adjustment at the time of warfarin initiation or at the matching quarterly update.

Overall, 144 patients with IPAH and 43 patients with SSc-PAH who initiated warfarin therapy after enrolment were identified, and matched with the same number of patients who were never receiving warfarin. Clinical characteristics and comorbid diseases were similar between the two sets of groups. No significant survival advantage was observed in patients with IPAH treated with warfarin, assessed using either the unadjusted Cox proportional hazards model (HR 1.42, 95% CI 0.86–2.32, P = 0.17) or the adjusted analysis for risk factors (HR 1.37, 95% CI 0.84–2.25, P = 0.21). An unadjusted survival analysis of patients with SSc-PAH showed that warfarin was associated with poorer survival compared with matched controls (HR 2.03, 95% CI 1.09–3.79, P = 0.03).

...REVEAL registry data provided no conclusive evidence to support the use of warfarin to reduce mortality in PAH patients

“Analyses of the REVEAL registry data provided no conclusive evidence to support the use of warfarin to reduce mortality in PAH patients,” conclude the study investigators. Given that these findings are inconsistent with the previous COMPERA studies with regard to use of anticoagulation in patients with IPAH, they believe “further studies are required to resolve this ongoing controversy”.