Evaluation of a proposed standard reporting system for preoperative angiograms in infrainguinal bypass procedures: angiographic correlates of measured runoff resistance.

Preoperative angiography is widely used to estimate runoff before peripheral vascular bypass surgery. The Ad Hoc Committee on Reporting Standards for the Society for Vascular Surgery and the International Society for Cardiovascular Surgery recently proposed an angiographic scoring system that grades the quality of vessels distal to the proposed bypass site and calculates an overall runoff score after adjusting each vessel score by an arbitrary weighting factor. We compared this score with intraoperatively measured runoff resistance in 67 patients undergoing infrainguinal bypass. Correlation between overall runoff score and measured resistance varied with the distal bypass site and was reasonably predictive for femoropopliteal above-knee bypasses (r = 0.67, p = 0.004, N = 17) and femoroposterior tibial bypasses (r = 0.73, p = 0.03, N = 9), but not for femoropopliteal below-knee (r = 0.05, p = 0.76, N = 34) or femoroperoneal (r = 0.57, p = 0.18, N = 7) bypasses. When multiple linear regression was used to calculate the weighting factors (rather than using arbitrarily assigned factors), the correlation between overall angiogram score and measured resistance improved substantially for femoropopliteal above-knee (r = 0.85, p = 0.00006), femoropopliteal below-knee (r = 0.50, p = 0.03) and femoroperoneal (r = 0.83, p = 0.02) bypasses. Correlation for the entire group of 67 patients improved from r = 0.30 (p = 0.02) to r = 0.64 (p = 0.0001). We conclude that the committee's scoring system correlates with measured runoff resistance but can be improved by the use of multiple linear regression to calculate weighting factors for each vessel in the outflow tract.