Abstract
BackgroundThe aim of this study was to delineate impacts of percutaneous coronary intervention (PCI), flow demand, and status of myocardium on graft flow.MethodsWe retrospectively assessed 736 individual coronary artery bypass grafts that had been created as the sole bypass graft for a vascular region in 405 patients. The grafts comprised 334 internal thoracic artery (ITA) to left anterior descending (LAD), 129 ITA and 65 saphenous vein grafts (SVG) to left circumflex (LCX), and 142 gastroepiploic artery (GEA) and 66 SVG to right coronary artery (RCA). Minimal luminal diameter, size of revascularized area, history of myocardial infarction, and PCI in the relevant area were examined to determine whether these factors are associated with flow insufficiency (FI), which was defined as ≤ 20 mL/min.ResultsFI developed in 123/736 grafts (16.7%) and correlated significantly with stenosis in the distal portion (23.0% vs. 12.8%, p = 0.0003). Prior myocardial infarction significantly correlated with FI in GEA–RCA (p = 0.002) and ITA–LCX grafts (p = 0.04). There was a history of PCI to the LAD (PCI group) in 54 ITA to LAD bypass grafts (16.2%), whereas the remaining 280 had no history of PCI to the LAD (no-PCI group). Graft flow was significantly greater in the no-PCI than in the PCI group (53 ± 29 vs. 42 ± 27; p = 0.006). The incidences of FI and graft failure were significantly higher in the PCI than the no-PCI group (22.2%, vs. 8.2%; p = 0.003; 9.2% vs. 1.8%; p = 0.003, respectively).ConclusionsPrior PCI has a negative impact on graft flow. The influences of small revascularized area, myocardial infarction, and PCI are greater, necessitating consideration of factors associated with flow demand or microvasculature when planning revascularization.
Highlights
The aim of this study was to delineate impacts of percutaneous coronary intervention (PCI), flow demand, and status of myocardium on graft flow
For internal thoracic artery (ITA) to left anterior descending (LAD) bypass grafts, the incidence of flow insufficiency (FI) in ITA to LAD with prior PCI was 22.2% (12/54), which is significantly higher than the 8.2% (23/280) in patients without prior PCI (p = 0.002)
For ITA to left circumflex (LCX) and gastroepiploic artery (GEA) to right coronary artery (RCA) grafts, the incidence of FI was significantly higher in patients with prior myocardial infarction (MI) in the revascularized area (p = 0.04 and p = 0.002, respectively)
Summary
The aim of this study was to delineate impacts of percutaneous coronary intervention (PCI), flow demand, and status of myocardium on graft flow. After coronary artery bypass grafting (CABG), flow to the relevant myocardial area comprises the sum of graft flow and native coronary flow. Prediction of native coronary flow has been improved by evaluating the severity of stenosis in the native coronary artery, for example, by measuring fractional flow reserve (FFR). If myocardial flow demand in the relevant area is smaller than a certain amount, graft flow may be insufficient to achieve long-term patency, irrespective of FFR value. The impact of flow demand has not yet been fully delineated. We have previously reported that the risk of graft failure increases fourfold or more when graft flow as measured by TTFM is insufficient [5]
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