“…There is strong pathophysiologic rationale for this type of therapy, as numerous studies have identified in situ thrombosis and a pro-coagulant milieu in PAH (3)(4)(5)(6)(7)(8)(9). Unfortunately, a paucity of randomized controlled studies has left practicing clinicians relying on a handful of observational investigations to guide practice patterns (1,2,10,11). Prior to publication of the Registry to Evaluate Early and Long-term PAH Disease Management (REVEAL) registry anticoagulation report, there were 9 cohort studies [2 prospective (12,13) and 7 retrospective (6,(14)(15)(16)(17)(18)(19)] specifically addressing the question of anticoagulation in PAH.…”