Left ventricular strain‐curve morphology to distinguish between constrictive pericarditis and restrictive cardiomyopathy

AIMS: To distinguish between constrictive pericarditis (CP) and restrictive cardiomyopathy (RCM) using cardiac magnetic resonance feature tracking (CMR‐FT) left ventricle (LV) diastolic time–strain curve patterns and myocardial strain. METHODS AND RESULTS: A total of 32 CP patients, 27 RCM patients, and 25 control subjects were examined by CMR‐FT and analysed for global strain, segmental strain, and LV time–strain curve patterns in the longitudinal, circumferential, and radial directions. Speckle tracking echocardiography (STE) strain imaging was performed in some cases. The peak global longitudinal strain (GLS) and global circumferential strain (GCS) of the RCM group were lower than those of the CP group. GLS [median (interquartile range) CP vs. RCM: −11.15 (−12.85, −9.35) vs. −6.5 (−8.75, −4.85), P < 0.001] and GCS (CP vs. RCM: −16.89 ± 5.11 vs. −13.37 ± 5.79, P < 0.001). In circumferential and radial directions, the strain ratios of the LV lateral/septal wall (LW/SW) of the CP group were significantly lower than those of the RCM group at the basal and mid segments. The CS ratio of LW/SW at the basal segment [CP vs. RCM: 0.95 (0.85, 1.25) vs. 1.43 (1.18, 1.89), P < 0.001] and mid segment [CP vs. RCM: 1.05 (0.92, 1.15) vs. 1.18 (1.06, 1.49), P = 0.026]. The RS ratio of LW/SW at the basal segment [CP vs. RCM: 0.97 (0.76, 1.37) vs. 1.55 (1.08, 2.31), P = 0.006] and mid segment [CP vs. RCM: 0.95 (0.70, 1.28) vs. 1.79 (1.32, 2.92), P < 0.001]. In the longitudinal and circumferential directions, the characteristic ‘plateau’ pattern of time–strain curves could be seen in the CP but not in the RCM during the diastole. The GCS ratio of 0–50%/50–75% diastolic period of the CP was higher than that of the RCM [CP vs. RCM: 17.01 (8.67, 23.75) vs. 5.38 (1.93, 11.24), P = 0.001], while the GCS ratio of 50–75%/75–100% diastolic period was lower than that of the RCM [CP vs. RCM: 0.36 (0.15, 1.67) vs. 1.12 (0.70, 5.58), P < 0.001]. The peak GLS (sensitivity, 85%; specificity, 78%) and the GCS ratio of 0–50%/50–75% diastolic period (sensitivity, 88%; specificity, 73%) had higher differential diagnosis value. CONCLUSIONS: The CMR‐FT could distinctly differentiate CP from RCM based on LV myocardial strain and LV time–strain curve patterns. The characteristic ‘plateau’ pattern of the time–strain curve is specific for CP and not RCM and this curve can also be duplicated by STE.