Right ventricular concentric hypertrophy and clinical worsening in idiopathic pulmonary arterial hypertension

Background As the pathophysiology of idiopathic pulmonary arterial hypertension (IPAH) is an afterload mismatch, wall stress represents the most important feature affecting the overloaded right ventricle (RV). Thus, RV mass/volume (M/V) ratio may reflect more adequately the suitability of the remodeling pattern in minimizing RV wall stress, compared to the lone RV volume. The aim of the study is to investigate the prognostic impact of RV M/V ratio in IPAH. Methods Seventy-four therapy-naïve IPAH patients were enrolled in our Center and prospectively followed-up for the presence of clinical worsening (CW). Baseline evaluation included clinical, hemodynamic and echocardiographic parameters. Cardiac magnetic resonance was used for RV M/V ratio determination. Results During 541±283 days of follow-up 31 of 74 patients presented CW (42%). Actuarial rates of CW were 14%, 28% and 46% at 6-12-24 months, respectively. RV M/V ratio significantly improved the power of the prognostic model based on traditional clinical, hemodynamic and imaging parameters (AUC 0.74 vs 0.66, respectively; p=0.01). Combining together the cut-off values of RV M/V ratio and cardiac index (CI) derived from ROC analysis, patients with low RV M/V ratio/low CI, low RV M/V ratio/high CI and high RV M/V ratio/low CI showed 28.8, 8.8 and 6.1 increase in the hazard ratio, respectively, compared with high RV M/V ratio/high CI patients (p=0.0001). Conclusions RV M/V ratio is an independent predictor of prognosis in IPAH and may allows clinicians to better stratify patients with normal CI, identifying at an early stage those patients at higher risk of right heart failure development before hemodynamic instability appearing.