Diagnostic Concordance of Echocardiography and CMR-Based Tissue Tracking for Differentiating Constrictive Pericarditis from Restrictive Cardiomyopathy Amaki et al: LV Mechanics in Constriction and Restriction

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