Impact of vascular flow reserve and below-knee runoff on tissue perfusion after lower extremity endovascular therapy

Background The physiological determinants of peripheral blood flow after endovascular therapy (EVT) for lower extremity artery disease (LEAD) remain incompletely understood. Below-knee (BK) runoff reflects distal inflow status, whereas vascular flow reserve (VFR) measured at the popliteal artery reflects microcirculatory function. However, the relationship between these parameters and post-EVT tissue perfusion assessed by skin perfusion pressure (SPP) remains unclear. Methods Fifty-seven consecutive patients who underwent EVT of the femoropopliteal artery were prospectively enrolled. Concomitant BK intervention was performed in patients with chronic limb-threatening ischemia (CLTI). BK runoff was evaluated, and VFR and fractional flow reserve (FFR) were measured in the popliteal artery immediately after EVT. Post-EVT SPP was assessed during hospitalization. Associations between clinical or physiological variables and low post-EVT SPP (<40 mmHg), defined as impaired lower leg tissue perfusion, were evaluated using logistic regression analyses. Results Univariate analysis identified VFR (odds ratio [OR], 0.39; 95% confidence interval [CI], 0.12–0.88; p=0.017), hemoglobin (OR, 0.52; 95% CI, 0.26–0.90; p=0.019), absence of BK runoff (OR, 27.5; 95% CI, 4.5–245; p=0.0003), diabetes (p<0.0001), and CLTI (OR, 7.5; 95% CI, 1.41–57.3; p=0.017) as associated with low post-EVT SPP. In multivariate analysis including BK runoff and VFR, absence of BK runoff was an independent predictor of low post-EVT SPP (OR 28.1, 95% CI 3.3–395; p=0.002), whereas VFR was not. Conclusions VFR was associated with impaired tissue perfusion after EVT; however, distal inflow status represented by BK runoff was the dominant determinant. These findings suggest that optimization of distal runoff may be essential to achieve adequate tissue perfusion after femoropopliteal EVT.