Non-invasive myocardial work as a tool in the asessment of the functional significance of non-culprit intermediate stenoses in patients with acute myocardial infarction

Introduction The decision to revascularize non-culprit intermediate coronary artery stenoses, especially in the setting of acute myocardial infarction, remains challenging. Even though we can assess them with functional, pressure-based tests such as fractional flow reserve (FFR) or with intravascular imaging, the accessibility of such tools during primary angioplasty is lacking. Myocardial work, similarly to myocardial strain, is an echocardiographic measurement which uses speckle-tracking in order to assess the longitudinal contraction of the myocardium. Additionally, in removes the influence of afterload by factoring in the patient’s non-invasive arterial pressure. Purpose We propose to use myocardial work in order to evaluate the functional significance of non-culprit intermediate stenoses in patients with acute myocardial infarction. Methods We included 121 patients with acute myocardial infarction, which had at least one intermediate stenosis on a non-culprit vessel, in either the proximal or the medial segment of the main coronary arteries: right coronary artery (RCA), left anterior descending artery (LAD), left circumflex artery (LCX). Between 3 to 5 days after primary angioplasty, we acquired echocardiographic images, followed by coronary angiogram with FFR acquisition. In total, we assessed 99 stenoses. Our main outcome was FFR value and our main predictors were: regional work index (RWI - average myocardial work index in the territory of the targeted coronary artery) and regional work efficiency (RWE - average myocardial work efficiency in the territory of the targeted coronary artery). The data was analyzed using SPSS Statistics 23.0. Results Out of the 99 intermediate stenoses, 18 (18,2%) were on RCA, 65 (65,7%) on LAD and 16 (16,2%) on LCX. 45 (45,4%) of them were in the proximal segment of their respective arteries, while 54 (54,5%) where in the medial segment. Mean FFR was 0,786 ± 0,093, mean RWI was 1491 ± 378 mmHg% and mean RWE was 91,2 ± 4,3%. 56 (56,6%) of the patients had an FFR below 0,8 and required angioplasty. Out of the independent variables, only RWI significantly predicted FFR (B = 0,87E-4, 95% Confidence Interval 0,4E-4 – 1,33E-4, p < 0,001; R = 0,352). We discovered similar results when evaluating only proximal stenoses, as well as when assessing only stenoses on LAD. Conclusion We discovered that regional work index, as described above, could predict the functional impact of non-culprit intermediate coronary stenoses in patients with acute myocardial infarction. Previously, similar indices using myocardial work have been shown to predict significant intermediate stenoses in patients with single-vessel disease. As far as we are aware of, our study is the first do do so in the setting of acute myocardial infarction. We believe that, after further research and validation, myocardial work could be used in order to assist the revascularization decision in such cases.