Photo Credit: Pitchayanan Kongkaew

The following is a summary of “Transit time flow management as a management strategy in high-risk groups undergoing coronary artery bypass grafting,” published in the March 2025 issue of the Journal of Cardiothoracic Surgery by Kucera et al.

This study aimed to evaluate the impact of transit-time flow measurement (TTFM) and high-frequency ultrasound on surgical decision-making and outcomes in patients undergoing coronary artery bypass grafting (CABG), with a particular focus on individuals with diabetes mellitus (DM), end-stage renal disease (ESRD), and those undergoing either on-pump (ONCAB) or off-pump (OPCAB) procedures. The objective was to determine whether the intraoperative use of these technologies influenced changes in surgical strategy and improved operative outcomes in high-risk patient populations. Data were derived from the multicenter REQUEST (Registry for Quality Assessment with Ultrasound Imaging and TTFM Measurement in Cardiac Bypass Surgery) study, which previously examined surgical outcomes across three separate subgroups: patients with DM, those with ESRD, and those undergoing ONCAB versus OPCAB. 

The primary endpoint assessed was any intraoperative change in the planned surgical procedure, while secondary endpoints included the rate of changes, the selection of coronary targets, the number of completed grafts, and in-hospital morbidity and mortality. The REQUEST registry included a total of 1,016 patients who underwent CABG. Among patients with diabetes, the rate of surgical modifications to coronary targets was slightly lower when TTFM was used (11.6% vs. 9.5%; OR 0.80, 95% CI 0.53–1.21, P = 0.288). However, patients with diabetes experienced a higher rate of intraoperative strategy changes to the aortic component of the procedure when TTFM was utilized (10.2% vs. 6.4%; OR 1.67, 95% CI 1.06–2.65, P = 0.026). In the ESRD subgroup, the use of TTFM led to a statistically significant increase in strategy changes compared to cases without TTFM (33.7% vs. 24.3%; OR 1.58, 95% CI 1.01–2.48, P = 0.047) and a higher rate of graft revisions (7.0% vs. 3.4%; OR 2.14, 95% CI 1.17–3.71). 

Regarding the surgical approach, 402 (39.6%) patients underwent OPCAB, while 614 (60.4%) underwent ONCAB. When TTFM and HFUS were employed, OPCAB procedures were associated with a significantly greater number of intraoperative strategy modifications involving the aortic portion of the operation (14.7% vs. 3.4%; OR 4.03, 95% CI 2.32–7.20), though no significant difference was observed in coronary target selection or graft revision rates. The overall in-hospital mortality reported in the REQUEST study was 0.6%. These findings underscore the significant influence of TTFM on intraoperative decision-making and surgical planning, particularly in patients with ESRD, DM, and those undergoing OPCAB procedures. The observed differences between OPCAB and ONCAB may be attributed to the higher mean graft flow in OPCAB cases, which, when evaluated using a standardized TTFM cutoff, facilitates the assessment of graft quality. 

Collectively, this study highlights the potential utility of TTFM as a valuable tool in CABG, demonstrating its positive impact on intraoperative strategy modifications and emphasizing its role in optimizing surgical outcomes in high-risk patient populations.

Source: cardiothoracicsurgery.biomedcentral.com/articles/10.1186/s13019-025-03408-8