Myocardial Work and Left Ventricular Contractile Reserve During Stress Echocardiography: An Angiographic Validation

Objective This study sought to determine the contractile reserve (CR) response to exercise stress echocardiography (ESE) quantified by the novel parameter, non-invasive myocardial work (MW), in subjects with angiographically proven coronary artery disease (CAD). Methods CR was measured by the relative change in ejection fraction (EF), global longitudinal strain (GLS) and MW indices from rest to peak exercise in 304 patients referred for clinically indicated ESE. Positive ESE patients proceeded to coronary angiography and further risk stratified based on either percutaneous or surgical intervention. Results CRGLS and global work index (CRGWI) significantly decreased with exercise induced ischaemia and angiographically proven significant CAD (CRGLS -1.6±3.5%; CRGWI -8.6±511mmHg% decrement, p<0.001) compared to non-ischaemic patients (CRGLS 1.4±2.2%; CRGWI 398±404mmHg% improvement). Global constructive work (CRGCW) was significantly higher (p<0.0001) in non-ischaemic (818±457mmHg%) and blunted in ischaemic patients (208±550mmHg%). CRGCW (AUC 0.81; 95%CI 0.74-0.88) was superior to CRGLS (AUC 0.75; 95%CI:0.67-0.83), CRGWI (AUC 0.73, 95%CI:0.64-0.82) and CREF (AUC 0.71; 95%CI:0.62-0.81, p<0.001) to detect inducible ischaemia. Subgroup analysis showed patients requiring surgical revascularisation demonstrated a significantly lower CRGWE (-11.5±7.6%, p<0.05) as a result of reduced CRGCW (281±573mmHg%, p<0.05) and increased global wasted work (CRGWW, 289±151mmHg%, p=0.09). Conclusion Multivessel disease requiring surgical revascularisation have the greatest reduction in CR. MW may potentially improve detection of ischaemia and further risk stratification during ESE to maximise the benefits of revascularisation.