Diagnostic Concordance of Echocardiography and Cardiac Magnetic Resonance-Based Tissue Tracking for Differentiating Constrictive Pericarditis From Restrictive Cardiomyopathy

Background—Variations in longitudinal deformation of the left ventricle have been suggested to be useful for differentiating chronic constrictive pericarditis (CP) and restrictive cardiomyopathy (RCM). We assessed left ventricular mechanics derived from cardiac magnetic resonance (CMR) cine–based and 2-dimensional echocardiography–based tissue tracking to determine intermodality consistency of diagnostic information for differentiating CP from RCM. Methods and Results—We retrospectively identified 92 patients who underwent both CMR and 2-dimensional echocardiography and who had a final diagnosis of CP (n=28), RCM (n=30), or no structural heart disease (n=34). Global longitudinal strain from long-axis views and circumferential strain from short-axis views were measured on 2-dimensional echocardiographic and CMR cine images using the same offline software. Logistic regression models with receiver operating characteristics curves, continuous net reclassification improvement, and the integrated discrimination improvement (IDI) were used for assessing the incremental predictive performance. Global longitudinal strain was higher in patients with CP than in those with RCM (P<0.001), and both techniques were found to have similar diagnostic value (area under the curve, 0.84 versus 0.88 for CMR and echocardiography, respectively). For echocardiography, the addition of global longitudinal strain to respiratory septal shift and early diastolic mitral annular velocity resulted in improved continuous net reclassification improvement (P<0.001 for both) and integrated discrimination improvement (P=0.005 and 0.024) for both models. Similarly, for CMR, the addition of global longitudinal strain to septal shift and pericardial thickness resulted in improved continuous net reclassification improvement (P<0.001 for both) and integrated discrimination improvement (P=0.003 and <0.001). Conclusions—CMR and echocardiography tissue tracking–derived left ventricular mechanics provide comparable diagnostic information for differentiating CP from RCM.