Different Target Stenosis Severity For Bilateral Internal Mammary Artery Y-graft Branches Does Not Influence The Outcome
Gabriele Di Giammarco, MD, Michele Di Mauro, MD, Daniele Marinelli, MD.
Department of Cardiac Surgery, University “G.D’Annunzio” Chieti-Pescara, Chieti, Italy.
OBJECTIVE: A great debate is open upon the likelihood that an unbalance grade of target stenosis of the two BIMA Y-graft branches could cause flow competition with increased graft failure. We used Transit-time flow measurement (TTFM) parameters to investigate the presence of flow competition between BIMA Y branches at the end of surgery.
METHODS: From August 2009 to December 2014, 211 patients, receiving LIMA to LAD and RIMA to lateral wall branches, were enrolled retrospectively in this study. “Graft flow competition” was defined as grafts with mean graft flow (MGF)≤15 ml/minute, pulsatily index (PI)≥3 and backward flow ≥ 3.
RESULTS: Thirty-three (15.6%) patients showed LIMA (8 cases) or RIMA (25 cases) flow competition at TTFM (Group A). In 8 cases of LIMA flow competition, LIMA branch showed significantly lower MFG (8, 6-10 ml/min vs 19ml/min 12-29, p = 0.012) with higher PI (5.3, 4.0-6.1 vs 1.6, 1.4-2.0, p = 0.010) and higher BF (17, 11-21 vs 0, 0-2.8, p = 0.009) compared to RIMA branch; Cx system showed significantly higher grade of stenosis compared to LAD. In 25 cases of RIMA flow competition, RIMA branch showed significantly lower MGF (9, 5-12 ml/min vs 18, 16-26ml/min, p < 0.001), higher PI (4.0, 3.5-5.1 vs 1.9, 1.4-2.7, p <0.001) and higher BF (7, 4-11 vs 0.5, 0-6.9, p = 0.014), compared to LIMA branch. In group B, the stenoses were balanced as well as no difference of TTFM parameters was found between BIMA branches. Early mortality was 1.4% without difference between groups. No difference was found between groups concerning 5-year survival (Group A 94%±4 vs Group B 93%±2, p = 0.99), cardiac survival (Group A 97%±3 vs Group B 96%±2, p = 0.96, event-free survival (Group A 87%±7 vs Group B 84%±4, p = 0.77) and cardiac event-free survival (Group A 94%±4 vs Group B 89%±3, p = 0.76)
CONCLUSIONS: A significant difference between native coronary stenosis causes different TTFM parameters between the two branches of BIMA Y-graft, indicating the presence of a flow of competition. This condition, however, does not show any clinical impact in the short and long term.
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