Left ventricular synchrony, torsion, and recoil mechanics in Ebstein's anomaly: insights from cardiovascular magnetic resonance

Background: Disease progression and heart failure development in Ebstein's Anomaly (EA) of the tricuspid valve is characterized by both right and left ventricular (LV) deterioration. The mechanisms underlying LV dysfunction and their role in heart failure development are incompletely understood. We hypothesized that LV dyssynchrony and impaired torsion and recoil mechanics induced by paradoxical movement of the basal septum may play a role in heart failure development. Methods: 31 EA patients and 31 matched controls underwent prospective cardiovascular magnetic resonance (CMR). CMR feature tracking (CMR-FT) was performed on apical, midventricular and basal short-axis and 4D-volume analysis was performed using three long-axis views and a short axis cine stack employing dedicated software. Circumferential uniformity ratio estimates (CURE) time-to-peak-based circumferential systolic dyssynchrony index (C-SDI), 4D volume analysis derived SDI (4D-SDI), torsion (Tor) and systolic (sysTR) and diastolic torsion rate (diasTR) were calculated for the LV. QRS duration, brain natriuretic peptide, NYHA and Total R/L-Volume Index (R/L Index) were obtained. Results: EA patients (31.5 years; controls 31.4 years) had significantly longer QRS duration (123.35 ms +/- 26.36 vs. 97.33 ms +/- 11.89 p < 0.01) and showed more LV dyssynchrony (4D-SDI 7.60% +/- 4.58 vs. 2.54% +/- 0.62, p < 0.001; CURE 0.77 +/- 0.05 vs. 0.86 +/- 0.03, p < 0.001; C-SDI 7.70 +/- 3.38 vs. 3.80 +/- 0.91, p = 0.001). There were significant associations of LV dyssynchrony with heart failure parameters and QRS duration. Although torsion and recoil mechanics did not differ significantly (p > 0.05) there was an association of torsion and recoil mechanics with dyssynchrony parameters CURE (sysTR r = -0.426; p = 0.017, diasTR r = 0.419; p = 0.019), 4D-SDI (sysTR r = 0.383; p = 0.044) and C-SDI (diasTR r = -0.364; p = 0.044). Conclusions: EA is characterized by LV intra-ventricular dyssynchrony, which is associated with heart failure and disease severity parameters. Markers of dyssynchrony can easily be quantified from CMR-FT, and may have a role in the assessment of altered cardiac function, carrying potential management implications for EA patients.