Trajectories and determinants of echocardiographic myocardial work indices after acute myocardial infarction: a pilot study

Introduction We evaluated the trajectories of echocardiographic myocardial work (MW) indices and their associations with left ventricle (LV) functional recovery, myocardial viability, and perfusion in patients with reperfused acute myocardial infarction (AMI). Methods Thirty-one patients with a first ST-elevation AMI treated with percutaneous coronary intervention were prospectively enrolled. Transthoracic echocardiography and [ 15 O]-water positron emission tomography (PET) were performed at a median of 7.7 ± 3.8 days post- intervention (baseline). Global and segmental absolute myocardial blood flow (MBF) were assessed using PET, and myocardial segments were graded as viable or non-viable based on perfusable tissue fraction (PTF). Echocardiographic parameters, including LV ejection fraction (LVEF), global longitudinal strain (GLS), myocardial work index (MWI), constructive work (MCW), wasted work (MWW), and work efficiency (MWE), were measured at baseline and at the 6-month follow-up. The myocardial area at risk (AAR) and the remote myocardium were defined based on the culprit coronary artery segment. Results LVEF and GLS remained unchanged between baseline and follow-up. However, global MWI, MCW, and MWE significantly increased, while MWW decreased at the 6 months (all p < 0.05). An increase in MWI, but not MWE, was associated with improvement of LVEF. Neither global MWI nor MWE correlated with global MBF, but were inversely associated with peak levels of troponin T and NT-proBNP. In the AAR, regional MWI and MWE were significantly correlated with regional MBF ( r = 0.53, p = 0.003, and r = 0.59, p < 0.001, respectively) and PTF ( r = 0.41, p = 0.03, and r = 0.65, p < 0.001, respectively). At baseline, segmental MWI and MWE were higher in viable compared to non-viable segments. At 6 months, MWI and MWE increased in viable, but not in non-viable segments. Conclusions Echocardiographic myocardial work indices reflect the severity of myocardial injury early after AMI and may serve as non-invasive markers of functional recovery and myocardial viability.