Right ventricular myocardial performance index as an early marker of cardiac dysfunction in systemic sclerosis

Systemic sclerosis (SSc) is associated with subclinical cardiac involvement often missed by conventional echocardiography. The right ventricular myocardial performance index (RV MPI), a Doppler-derived composite of systolic and diastolic function, has been proposed as an early marker of right ventricular (RV) dysfunction. This study was conducted to compare RV MPI between SSc patients and healthy controls and to determine its association with clinical and functional features of SSc.

A cross-sectional study was performed in 60 patients with SSc and 83 age-matched healthy controls, all women. Comprehensive transthoracic echocardiography, including pulsed-wave Doppler of RV inflow and outflow, was used to calculate RV MPI as (IVCT + IVRT)/ET. Tricuspid annular plane systolic excursion (TAPSE) and the TAPSE/systolic pulmonary artery pressure (TAPSE/sPAP) ratio were recorded, together with disease duration, modified Rodnan skin score (mRSS) and pulmonary function tests (FVC, DLCO). Group comparisons and correlation analyses were conducted, and multivariable logistic regression and receiver operating characteristic (ROC) analyses were applied.

Left ventricular ejection fraction was similar between groups (median 60% vs. 61%), whereas RV MPI was found to be significantly higher in SSc than in controls (median 0.54 vs. 0.35, p < 0.001). Higher pulmonary artery systolic pressure, lower TAPSE and a reduced TAPSE/sPAP ratio were also observed in SSc (all p < 0.001). After adjustment for age and TAPSE/sPAP, RV MPI remained independently associated with SSc status. ROC analysis demonstrated excellent discrimination for SSc by RV MPI (area under the curve 0.92; threshold 0.47; sensitivity 78%, specificity 94%), whereas. TAPSE/sPAP showed only moderate discrimination. RV MPI was not significantly correlated with CRP, FVC, DLCO, mRSS or disease duration. In patients with interstitial lung disease, higher MPI values and more frequent DLCO < 80% were detected.

RV MPI was shown to be significantly increased in SSc, even in the absence of overt cardiac symptoms or reduced left ventricular ejection fraction and remained independently associated with SSc. Together with reduced TAPSE and TAPSE/sPAP ratios, these findings indicate impaired RV-pulmonary arterial coupling. RV MPI therefore appears to be a simple and sensitive non-invasive parameter for the identification of cardiac involvement in SSc.