An Alternative Biventricular Tracking Approach for Assessment of Right Ventricular Strain in Cardiac Amyloidosis

Background: Cardiac amyloidosis is characterized by progressive myocardial infiltration leading to ventricular dysfunction. While left ventricular strain assessment is well established, evaluation of right ventricular (RV) mechanics remains challenging because of the ventricle's complex geometry and limitations of conventional speckle-tracking methods. We aimed to evaluate an alternative approach for RV strain assessment based on a continuous biventricular tracking pathway within the apical four-chamber view. Methods: We retrospectively studied 32 patients with cardiac amyloidosis and 32 age-, sex-, rhythm-, and ejection fraction-matched controls. RV free-wall longitudinal strain was measured using a novel investigational biventricular tracking approach from the basal RV free wall through the apex to the basal lateral left ventricular wall and compared with conventional RV strain. Investigational biventricular strain (BVS) was also obtained automatically as a surrogate marker of global ventricular function. Reproducibility was assessed in a subset of 20 patients using intraclass correlation coefficients (ICC), coefficient of variation (CV), and Bland-Altman analysis. Results: Investigational RV free-wall strain was significantly reduced in patients with cardiac amyloidosis compared with controls (-15.3 ± 4.1% vs. -21.2 ± 5.4%, p < 0.001). Compared with conventional RV strain, the investigational biventricular tracking approach yielded more negative global RV strain values in both patients with amyloidosis (-15.3 ± 4.1% vs. -13.8 ± 4.8%, p = 0.003) and controls (-21.2 ± 5.4% vs. -17.4 ± 5.8%, p < 0.001). The greatest differences were observed at the apical RV segment. Bland-Altman analysis demonstrated a mean bias of -2.64 percentage points with 95% limits of agreement from -8.41 to +3.12 percentage points. A significant regional deformation pattern along the investigational tracking contour was observed in patients with cardiac amyloidosis (p < 0.001), whereas no significant regional variation was observed in controls. BVS correlated strongly with LV global longitudinal strain (r = 0.83 in amyloidosis; r = 0.58 in controls; r = 0.84 overall; all p < 0.001). Inter- and intra-observer reproducibility of investigational RV free-wall strain was excellent (ICC 0.976 and 0.985, respectively). Conclusions: The investigational biventricular tracking approach is a feasible and highly reproducible method for assessing ventricular longitudinal deformation using a single continuous contour. It provides complementary information while remaining an exploratory investigational technique. Further studies are required to validate its anatomical specificity, clinical applicability, and prognostic value.