CT pulmonary angiography combined with echocardiography in suspected systemic sclerosis-associated pulmonary arterial hypertension

Objective. Echocardiography is widely used in the investigation of patients with suspected SSc-associated pulmonary arterial hypertension (SSc-PAH). We investigated whether CT pulmonary angiography (CTPA) provides additive diagnostic value. Methods. Data for 89 consecutive patients with suspected SSc-PAH undergoing echocardiography, CTPA and right heart catheterization were reviewed. Pulmonary artery diameter (dPA) and ascending aorta diameter (dAA), right and left ventricular diameter (dRV and dLV) and grade of tricuspid regurgitation (TRCT) measured at CTPA and tricuspid gradient (TGECHO) at echocardiography were retrieved. A predictive equation for mean pulmonary arterial pressure (mPAP) was derived using multivariate linear regression. Multivariate Cox regression analysis was then used to assess the prognostic strength of CTPA parameters and TGECHO. Results. Absolute measures of dPA and dRV correlated weakly with mPAP. However, dPA : dAA and dRV : dLV showed stronger correlations with mPAP (dPA : dAA r = 0.42, P < 0.001; dRV : dLV r = 0.51, P < 0.001). dRV : dLV correlated more strongly with pulmonary vascular resistance than did dPA : dAA (r = 0.63 vs 0.39, P both <0.001). dPA : dAA and TGECHO were independent predictors of mPAP. A derived CT/echo composite index had a higher predictive accuracy (area under the curve = 0.95) than dPA : dAA or TGECHO although negative predictive value (NPV) was only 77%. Combining the CT/echo composite index with presence or absence of TRCT increased NPV to 100% although this observation requires further validation. dRV : dLV was the strongest prognostic factor.