Right ventricular arterial coupling in PAH: idiopatic versus systemic sclerosis-associated pulmonary arterial hypertension

Abstract Background Pulmonary arterial hypertension (PAH) is a severe complication of Systemic Sclerosis (SSc) leading to high morbidity and mortality. Objective To compare the TAPSE/PASP ratio, as a surrogate of ventricular-arterial coupling, in two matched cohorts of patients with idiopathic and SSc-associated PAH. Methods Two hundred and two consecutive patients with SSc-PAH matched for age, gender, body max index, and pulmonary vascular resistance (PVR), with 201 idiopathic PAH (IPAH) patients, were enrolled. Physical examination, WHO functional class, 6-minute walk distance (6MWD), right heart catheterization, echocardiographic assessment and European guidelines-derived risk score were assessed at baseline. Results the distribution of TAPSE/PASP between IPAH and SSc-PAH patients diverged for PVR≥5 WU (ROC-derived logistic analysis, Sp 99%, Se 51%; AUC=0.89, 95% CI 0.85-0.92, p0.0001). Considering patients with PVR ≥5, fewer SSc-PAH patients were at low risk compared with IPAH (low risk:11 patients, 7% vs 36 patients, 20%). SSc-PAH had more advanced WHO functional class, more impaired exercise capacity, higher NT-proBNP, higher right atrial pressure, and lower cardiac index (respectively, WHO III/IV:129 patients, 84% vs 126 patients, 72%, p=0.01; 6MWD: 335 ± 106m vs 367 ± 114m, p=0.01; NT-proBNP: 535 ± 696 pg/ml vs 212 ± 407 pg/ml, p=ns, RAP: 9.3 ± 4.6mmHg vs 7.5 ± 3.9mmHg, p0.001; CI values: 2.2 ± 0.5 l/min/m2 vs 2.4 ± 0.6 l/min/m2,p=0.01). RV systolic function and RV-PA coupling were significantly reduced in the SSc-PAH population compared with the IPAH patients (TAPSE values: 15±4mm vs. 18±4mm, p0.001;TAPSE/PASP ratio: 0.22±0.09mm/mmHg vs. 0.27±0.08mm/mmHg,p 0.001). Conclusion SSc-PAH patients with PVR≥5 had less favorable RV adaptation to increased afterload, resulting in increased filling pressures, higher BNP plasma level, more impaired TAPSE/PASP and finally lower cardiac index compared with IPAH.Correlations between TAPSE/PASP and PVR ROC curve by logistic analysis