Left ventricular eccentricity impairs three-dimensional systolic radial strain and torsion in patients after repair of tetralogy of fallot: a three-dimensional speckle tracking analysis

Abstract

BACKGROUND: Left ventricular (LV) systolic dysfunction has been shown to be a predictor of adverse outcomes after tetralogy of Fallot repair. OBJECTIVES: Using three-dimensional (3D) speckle tracking that simultaneously interrogates 3D myocardial deformation and torsion of all LV segments, we tested the hypothesis that LV eccentricity may impair LV 3D systolic radial strain and torsion and has implications on LV ejection fraction in postoperative Fallot patients. METHODS: Eighteen patients aged 21.5±8.2 years and 12 controls were studied. The 3D volume datasets were acquired (Artida, Toshiba, Japan) for assessment of LV 3D radial strain, time-to-peak strain, twist, torsion (twist/distance from LV base), and ejection fraction. The LV diastolic eccentricity index (EI) and indexed right ventricular end-diastolic area were determined from 2D images. RESULTS: Compared with controls, patients had significantly reduced LV global 3D radial strain (29.3±7.5% vs 36.9±7.4%, p=0.01), twist (6.9±3.2 degree vs 13.8±4.3 degree, p<0.001), and torsion (1.5±0.7 degree/cm vs 2.9±1.2 degree/cm, p=0.002), but greater LV EI (1.3±0.18 vs 1.1±0.04, p<0.001) and time-to-peak strain (418±31 ms vs 338±44 ms, p<0.001). Regional 3D strain of the basal septal (p=0.003), basal inferior (p=0.032), mid-anteroseptal (p=0.002), and mid-septal (p<0.001) segments were significantly lower in patients than controls. The LV diastolic EI correlated negatively with LV twist (r=-0.39, p=0.033), torsion (r=-0.39, p=0.036), and average septal 3D strain (r=-0.42, p=0.021), but positively with right ventricular end-diastolic area (r=0.78, p<0.001). The LV ejection fraction correlated significantly with LV EI (r=-0.61, p<0.001), global 3D strain (r=0.57, p=0.001), twist (r=0.65, p<0.001), and torsion (r=0.67, p<0.001). CONCLUSION: Left ventricular eccentricity secondary to right ventricular volume overload may lead to reduction of ejection fraction through impairment of 3D systolic radial strain and torsion in patients after Fallot repair.