Prognosis

Estimated median survival in IPAH, without specific therapies, is 2.8 years, with 1-year, 3-year, and 5-year survival rates of 68%, 48%, and 34%, respectively.[93]

Impact of therapy on survival

Epoprostenol therapy improves survival in IPAH.[65] In one large series, 1-year, 2-year, 3-year, 4-year, and 5-year survival rates were 88%, 76%, 63%, 56%, and 47%, respectively, compared with 1-year, 2-year, and 3-year predicted survival rates (based on the US National Institutes of Health [NIH] registry equation) of 59%, 46%, and 35%, respectively.[94] Less robust data suggest that warfarin and oral calcium-channel blockers in acute vasoreactive patients also prolong survival.[95] Meta-analysis of all placebo-controlled randomised trials showed that pulmonary arterial hypertension (PAH)-targeted therapies reduce all-cause mortality.[96][97] In addition, observational registry data confirmed an improvement in survival in IPAH, with 1-year, 3-year, and 5-year survival rates of 91%, 74%, and 65%, respectively.[98]

Baseline prognostic factors

The following are associated with worse prognosis: syncope; male sex; older age; renal insufficiency; New York Heart Association (NYHA) functional class IV; short 6-minute walk distance (6MWD) (variable cut-offs in different studies, approximately <300 to 440 metres); echocardiography showing pericardial effusion and/or tricuspid annular plane systolic excursion <1.5 cm; elevated B-type natriuretic peptide (BNP) levels (>180 nanograms/L or >180 picograms/mL); and invasive haemodynamics showing right atrial pressure >15 mmHg and/or cardiac index ≤2 L/minute/m².​[99][100]

Prognostic factors after therapy

The following are associated with worse prognosis: NYHA classes III and IV; 6MWD <380 metres; elevated BNP levels; low cardiac index; and high right atrial pressure. It is debatable whether absolute values or changes in these parameters compared with baseline are predictors of outcome. Emerging evidence suggests that the change in 6MWD is not predictive of clinical events.[101] One study demonstrated that changes in NYHA functional class, cardiac index, mixed venous oxygen saturation, and N-terminal pro-BNP (NT-proBNP) were predictive of transplant-free survival. Specifically, the achievement with therapy of NYHA classes I or II, a cardiac index ≥ 2.5 L/minute/m², or a mixed venous oxygen saturation ≥65% was associated with improved survival.[102]

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