Transit time flow management as a management strategy in high-risk groups undergoing coronary artery bypass grafting

We evaluated the surgical outcomes in three groups of individuals with diabetes mellitus (DM), end-stage renal disease (ESRD), and on (ONCAB) vs. off-pump (OPCAB) coronary artery bypass grafting (CABG). We also examined the changes in intraoperative decision-making when ultrasound and transit-time flow measurement was utilized in the operating room. This study will aim to identify the utility of HFUS and TTFM in high-risk patient categories.

Data from the multicenter REQUEST (Registry for Quality assessment with ultrasound imaging and TTFM measurement in cardiac bypass surgery) had recently been compiled in three separate papers examining outcomes in patients with DM, ESRD, and on vs. off-pump bypass grafting. Data was extrapolated to determine the impact of HFUS and TTFM in patients with diabetes, ESRD, ONCAB and OPCAB. The primary outcome measured in in the REQUEST study is any change in planned surgical procedure. Secondary end points include rate of changes, coronary targets, completed grafts, and in-hospital morbidity and mortality.

Outcomes were predicated upon patient population surveyed. The REQUEST registry reported 1016 individuals who underwent CABG. For individuals with DM, any surgical change to the coronary target was slightly lower, measured at a change rate of 11.6% vs. 9.5% (OR 0.80, 95% CI 0.53-1.21, P = 0.288). In diabetics, the aortic component of the operation underwent a higher rate of surgical strategy change with TTFM compared to without (10.2% vs. 6.4%, OR 1.67, 95% CI 1.06-2.65; P = 0.026). In patients with ESRD, TTFM increased the rate of strategy changes compared to no TTFM (33.7% vs. 24.3%, 95% CI 1.01-2.48, P = 0.047) and number of revisions per graft (7.0% vs. 3.4%, OR 2.14, 95% CI 1.17-3.71). In the 1016 individuals who underwent CABG, 402 (39.6%) underwent OPCAB and 614 (60.4%) undergoing ONCAB. When TTFM and HFUS were utilized, OPCAB resulted in greater number of strategy changes for aortic portion of the procedure (14.7% vs. 3.4%, OR 4.03, CI 2.32-7.20) without a difference in coronary target or graft revision. In the REQUEST study, in-hospital mortality was published at 0.6%.

TTFM use demonstrates a statistically significant impact on intra-operative decision making and operative strategy changes in patients with concomitant ESRD, DM and who are undergoing OPCAB relative to ONCAB. This difference in OPCAB vs. ONCAB may be related to higher mean graft flows in OPCAB in the setting of a standardized TTFM cutoff for determination of graft quality. This data cumulatively suggests there a role for TTFM in CABG, namely due to its positive impact on outcome and statistically significant impact on intra-operative decision making.