Intraoperative Transit-Time Flow Measurement in CABG: Insights from the Registry for Quality Assessment (RE-QUEST) Study

Objectives: ESC/EACTS guidelines on myocardial revascularization recommend that “Routine intraoperative graft flow measurement should be considered” and “Minimization of aortic manipulation is recommended.” We undertook a large prospective registry (REQUEST) to determine how frequently routine high-frequency ultrasound (HFUS) assessment of the ascending aorta, native coronary artery and conduits, and transit time flowmetry (TTFM) of graft flow led to changes in surgical strategy.

Methods: Between April 2015 and December 2017, a total of 1,016 patients undergoing CABG in four European and three North American centers were prospectively enrolled into the REQUEST registry. The primary endpoint was any change in the planned surgical procedure. Major secondary endpoints consisted of the rate and reason for any surgical change related to the aorta, conduits, coronary targets, completed grafts and anastomotic revisions, and the rates of in-hospital mortality and major morbidity.

Results: The mean patient age was 65.9 years, 14.0% were female, and diabetes was present in 39.6%. Off-pump procedures were performed in 40.1% and bilateral internal thoracic arteries were used in 30.5%. The primary endpoint occurred in 25.3% (257/1,016) of patients. Changes in surgical strategy were related to the aorta in 10.0%, conduits in 2.7%, and coronary targets in 22.4%. Graft revision occurred in 8.3% of patients, including anastomotic revisions in 7.8%. In-hospital adverse event rates were 0.6% for mortality, 1.0% for stroke or transient ischemic attack, 0.3% for myocardial infarction, and 0.1% for repeat revascularization.

Conclusion: In the prospective, multicenter REQUEST study, surgical changes related to the aorta, conduits or coronary targets, and graft revisions were made in a quarter of all patients. This was associated with low operative mortality and major morbidity. By objectively guiding changes in the proposed CABG procedure, intraoperative combined assessment with TTFM and HFUS can improve the quality, safety, and efficacy of CABG and should be considered as a routine procedural aspect.