Diagnostic value of coronary flow acceleration measured by transesophageal echocardiography in coronary artery bypass graft surgery

Background: Transesophageal echocardiography as a method of intraoperative coronary flow assessment is largely unstudied. Objective: To evaluate the potential of intraoperative transesophageal echocardiography in diagnosing proximal coronary artery stenoses, to reveal the correlation between stenoses found on coronary angiography and coronary flow velocity in the corresponding area measured by intraoperative transesophageal echocardiography, and to study how coronary flow velocity changes before and after coronary artery bypass graft surgery and how it is related to postoperative myocardial injury. Methods: Our prospective cohort study included 186 patients scheduled for coronary artery bypass graft surgery. All the patients underwent intraoperative transesophageal echocardiography: coronary flow velocity was measured in the area of its acceleration (proximal parts of the left coronary artery) before and after the surgery. Troponin I was measured on the first postoperative day. Results: The areas of accelerated coronary flow before the procedure were detected in the left main coronary artery (88 patients, 47.3%), left anterior descending artery (146 patients, 78.5%), and left circumflex artery (28 patients, 15.1%). ROC analysis showed that coronary flow velocity of >73 cm/s in the left main coronary artery and of >91 cm/s in the left circumflex artery was associated with a stenosis of 50% and 70% in the respective arteries measured by coronary angiography. Furthermore, an increase in coronary flow velocity in the left anterior descending artery or its decrease by 4 cm/s after coronary artery bypass graft surgery are predictors of a 10-fold increase in troponin I concentration in the postoperative period. Conclusion: Coronary flow velocity assessment during intraoperative transesophageal echocardiography can offer added value in detecting clinically significant coronary artery stenoses, while assessment of changes in velocity may predict perioperative myocardial injury.