Inward Displacement: A Novel Method of Regional Left Ventricular Functional Assessment for Left Ventriculoplasty Interventions in Heart Failure with Reduced Ejection Fraction (HFrEF).

ABSTRACT

BACKGROUND: Hybrid minimally invasive left ventricular reconstruction is used to treat patients with ischemic heart failure with reduced ejection fraction (HFrEF) and antero-apical scar. Pre- and post-procedural regional functional left ventricular assessment with current imaging techniques remains limited. We evaluated 'inward displacement' as a novel technique of assessing regional left ventricular function in an ischemic HFrEF population who underwent left ventricular reconstruction with the Revivent System. METHODS: Inward displacement adopts three standard long-axis views obtained during cardiac MRI or CT and assesses the degree of inward endocardial wall motion towards the true left ventricular center of contraction. For each of the standard 17 left ventricular segments, regional inward displacement is measured in mm and expressed as a percentage of the maximal theoretical distance each segment can contract towards the centerline. The left ventricle was divided into three regions, obtaining the arithmetic average of inward displacement or speckle tracking echocardiographic strain at the left ventricular base (segments 1-6), mid-cavity (segments 7-12) and apex (segments 13-17). Inward displacement was measured using computed tomography or cardiac magnetic resonance imaging and compared pre- and post-procedurally in ischemic HFrEF patients who underwent left ventricular reconstruction with the Revivent System (n = 36). In a subset of patients who underwent baseline speckle tracking echocardiography, pre-procedural inward displacement was compared with left ventricular regional echocardiographic strain (n = 15). RESULTS: Inward displacement of basal and mid-cavity left ventricular segments increased by 27% (p < 0.001) and 37% (p < 0.001), respectively, following left ventricular reconstruction. A significant overall decrease in both the left ventricular end systolic volume index and end diastolic volume index of 31% (p < 0.001) and 26% (p < 0.001), respectively, was detected, along with a 20% increase in left ventricular ejection fraction (p = 0.005). A significant correlation between inward displacement and speckle tracking echocardiographic strain was noted within the basal (R = -0.77, p < 0.001) and mid-cavity left ventricular segments (R = -0.65, p = 0.004), respectively. Inward displacement resulted in relatively larger measurement values compared to speckle tracking echocardiography, with a mean difference of absolute values of -3.33 and -7.41 for the left ventricular base and mid-cavity, respectively. CONCLUSIONS: Obviating the limitations of echocardiography, inward displacement was found to highly correlate with speckle tracking echocardiographic strain to evaluate regional segmental left ventricular function. Significant improvements in basal and mid-cavity left ventricular contractility were demonstrated in ischemic HFrEF patients following left ventricular reconstruction of large antero-apical scars, consistent with the concept of reverse left ventricular remodeling at a distance. Inward displacement holds significant promise in the HFrEF population being evaluated pre- and post-left ventriculoplasty procedures.