Abstract
Introduction: Inspiratory muscle weakness (IMW) is frequently found in patients with pulmonary arterial hypertension (PAH). Mechanisms may be related to the underlying cardiovascular impairment. Therefore, we hypothesize that IMW may have a role on prognosis of patients with PAH. Objective: To assess the association of IMW with mortality in patients with PAH.
Methods: 50 patients with PAH [46±14 yrs; 78% female; 68% NYHA functional class (FC) I/II; mean pulmonary artery pressure 59±16mmHg; cardiac index 2.44±1,37L/min/m2], underwent a 6-minute walk test (6MWT) and maximum inspiratory pressure (MIP) measurements. The initial assessment was in 2012 and the follow-up was until December 2016. Cuttoff values were obtained by ROC curve analysis.
Results: Patients walked a mean of 425±90m and presented MIP of 67±19 CmH2O (73±17% predicted). Of note, 44% of the patients had MIP less than 70% of predicted. In the univariate analysis, MIP <50cmH20 [HR 4.6 (95% CI 1.6-13.3)], PiMAX <70%pred [HR 3.6 (95% CI 1.2-10.7)], NYHA FC III/IV [HR 3.3 (95%CI 1.1-9.1)] and distance walked less than 380 meters [HR 3.9 (95% CI 1.3-11.5)] were associated with mortality, independently of PAH classification. In the multivariate analysis, MIP less than 50 was an independent predictor of death.
Conclusions: IMW is associated with survival of patients with PAH, independently of haemodynamics, FC and the 6MWD. The absolute values were more accurate to determine survival than predicted values.
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