Does a well developed collateral circulation predispose to restenosis after percutaneous coronary intervention? An intravascular ultrasound study

Objective: To evaluate whether a well developed collateral circulation predisposes to restenosis after percutaneous coronary intervention (PCI). Design: Prospective observational study. Patients and setting: 58 patients undergoing elective single vessel PCI in a tertiary referral interventional cardiac unit in the UK. Methods: Collateral flow index (CFI) was calculated as (P_w-P_v)/(P_a-P_v), where P _a, P_w, and P_v are aortic, coronary wedge, and right atrial pressures during maximum hyperaemia. Collateral supply was considered poor (CFI < 0.25) or good (CFI ≥ 0.25). Main outcome measures: In-stent restenosis six months after PCI, classified as neointimal volume ≥ 25% stent volume on intravascular ultrasound (IVUS), or minimum lumen area ≤ 50% stent area on IVUS, or minimum lumen diameter ≤ 50% reference vessel diameter on quantitative coronary angiography. Results: Patients with good collaterals had more severe coronary stenoses at baseline (90 (11)% v 75 (16)%, p < 0.001). Restenosis rates were similar in poor and good collateral groups (35% v 43%, p = 0.76 for diameter restenosis, 27% v 45%, p = 0.34 for area restenosis, and 23% v 24%, p = 0.84 for volumetric restenosis). CFI was not correlated with diameter, area, or volumetric restenosis (r² < 0.1 for each). By multivariate analysis, stent diameter, stent length, > 10% residual stenosis, and smoking history were predictive of restenosis. Conclusion: A well developed collateral circulation does not predict an increased risk of restenosis after PCI.