Abstract
BACKGROUND: Echocardiographic tricuspid annular plane systolic excursion (TAPSE) to systolic pulmonary arterial pressure (sPAP) ratio is a noninvasive surrogate for right ventricle (RV)-pulmonary arterial (PA) coupling. It has been related to outcome in patients with moderate to severe pulmonary hypertension (PH). RESEARCH QUESTION: Is RV-PA coupling of prognostic relevance in patients with suspected PH, but only normal or mildly elevated mean pulmonary arterial pressure (mPAP), and is it associated with impaired exercise capacity and exercise hemodynamics? STUDY DESIGN AND METHODS: Patients with mPAP of < 25 mm Hg who underwent echocardiography and exercise right heart catheterization in our PH clinic were analyzed retrospectively. Mild PH was defined as mPAP of 21 to 24 mm Hg and exercise PH (EPH) was defined as a mPAP to cardiac output (CO) slope of > 3 mm Hg/L/min. Multivariate analysis was performed to identify independent predictors for clinical worsening (CW), defined by disease-related hospitalization, transplantation, or death. RESULTS: Two hundred thirty-seven patients (155 female with median age, 64 years [interquartile range (IQR), 54-73 years]; no PH: n = 147; mild PH: n = 90; EPH: n = 202) were included. During the observation time of 63 months (IQR, 29-104 months), 36 patients died and 126 clinical worsening events occurred. TAPSE to sPAP ratio was an age- and sex-independent predictor of mortality (hazard ratio [HR], 0.09; 95% CI, 0.01-0.62; P = .014) and clinical worsening (HR, 0.05; 95% CI, 0.35-0.78; P = .002). TAPSE to sPAP ratio also was correlated significantly to 6-min walk distance (r = 0.33; P < .001) and exercise hemodynamics (mPAP to CO slope: r(ρ) = -0.56; P < .001). The best multivariate predictive model for clinical worsening in this population consisted of TAPSE to sPAP ratio (HR, 0.71; 95% CI, 0.53-0.95; P = .021), N-terminal pro-brain natriuretic peptide (HR, 1.15; 95% CI, 0.99-1.34; P = .065), and 6-min walk distance (HR, 0.998; 95% CI, 0.995-1.00; P = .042). INTERPRETATION: Our results indicate that in patients with suspected PH, but normal or only mildly elevated resting mPAP, TAPSE to sPAP ratio is an independent predictor of outcome. In addition, it is associated significantly with exercise capacity and exercise hemodynamics and may be a helpful tool in the prediction of future clinical worsening of this patient population.