ABSTRACT
Pulmonary arterial hypertension (PAH) is a rare disease in which remodeling of the pulmonary vasculature progressively leads to increased pulmonary vascular resistance, right ventricular failure, and ultimately death (1). While there have been many developments in the medical therapy of this condition, when it progresses to severe disease in patients who are otherwise suitable for consideration of transplantation, then such patients should be referred for this procedure in a timely manner. Severity of disease is determined according to the World Health Organization (WHO) Functional Class (FC). Severe PAH (WHO FC IV) may encompass patients presenting in FC IV (the French PAH registry reported 12% of patients as presenting in FC IV [2]); patients not responding adequately and/or those not meeting treatment goals, and patients who progress or deteriorate on maximal therapy to FC III or IV also can be regarded as having severe disease and warrant consideration of transplant referral. Patients in FC IV have lower exercise capacity (as measured by 6-minute walk distance [6MWD]), higher right atrial pressure (RAP), lower cardiac index (CI), increased pulmonary vascular resistance index, and lower peak oxygen consumption compared with patients in FC IIII (2). The prognosis for patients with severe PAH is poor
with the French registry reporting patients in FC IV at enrollment had a 3-year survival of 38% compared to 80% for WHO FC I/II and 60% for WHO FC III (2). A study of national incident cases from the United Kingdom including 14% of patients in FC IV found a significantly reduced risk of death in patients with FC I/II or III (HR 0.3, p = .007 and HR 0.5 p = .01, respectively) (3) when compared with FC IV. Despite advances in medical therapy, PAH remains a chronic and progressive disease, and patients with severe disease who deteriorate to FC IV require timely evaluation regarding lung transplantation as a potential treatment.
