Complex myocardial mechanics in adult patients with repaired TOF- A novel study assessing myocardial work and mechanical dispersion at rest and during exercise

Abstract

Abstract Funding Acknowledgements Type of funding sources: None. Background Assessment of LV myocardial work (MW) and biventricular mechanical dispersion (MD) in patient with repaired TOF (rTOF) is novel. We sought to investigate the LV MW and biventricular MD response during stress echocardiography. Methods We analysed MW and MD at baseline and at low exercise intensity for 100 adult patients with repaired TOF, 60 patients with severe pulmonary regurgitation (SPR), and 40 patients with negligible PR (NPR). MW was derived as the area of pressure strain loop using speckle tracking echocardiography and blood pressure. MD was derived as the SD of time Q/R wave on ECG to peak longitudinal strain and expressed in millisecond. Results Reduced MW indices were observed in the entire population with mean global work efficiency (MWE) was 85±7%. Overall mean of global work index (GWI) was 1198±312mmHg%, 1701±303mmHg% for global constructive work (GCW), and 293±194mmHg% for global wasted work (GWW). The SPR group had lower MWE, lower GCW and higher GWW. During exercise, overall ΔMWE decreased by −2±10%, ΔGWI increased by 36±43%, ΔGCW increased by 68±40%, and ΔGWW increased by 120±110%. Overall resting mean value of RVMD was 46±18,ms, while 64±11,ms for LVMD, and higher values were observed during exercise. Changes in MWE, MWW, and LV and RVMD were closely associated with peak oxygen uptake (r=.33, r=.41, r=.36, r=.47, p<0.001). Conclusions LV MW indices are reduced and biventricular MD are pronounced in rTOF patients. Augmentation of MW parameters and timing were associated with objective exercise ability, suggesting that they are potential determinants of cardiopulmonary capability.