Vascular flow reserve immediately after infrapopliteal intervention as a predictor of wound healing in patients with foot tissue loss.

BACKGROUND The purpose of this study was to verify whether the concept of coronary blood flow reserve can be applied to patients with critical limb ischemia who are undergoing endovascular treatment (EVT) for isolated infrapopliteal lesions. METHODS AND RESULTS Forty patients diagnosed with critical limb ischemia (Rutherford category 5) who were undergoing EVT for isolated infrapopliteal lesions were prospectively enrolled. All lesions were treated with conventional balloon angioplasty without stent placement. After successful EVT, a pressure/temperature sensor-tipped guidewire was positioned in the proximal popliteal artery. Using the thermodilution technique, the mean transit time (Tmn) was determined after bolus injections of 3-mL saline at baseline and at the onset of intra-arterial papaverine induced maximum hyperemia. Vascular flow reserve (VFR) was calculated as resting Tmn divided by hyperemic Tmn. Complete epithelialization of the reference wound (wound healing) was completely closed by either surgical or secondary intervention within 3 months after EVT. Wound healing was achieved in 22 patients after EVT (healing group) but was not achieved in 18 patients (nonhealing group). Postprocedural VFR was significantly lower in the nonhealing group than in the healing group (2.40; interquartile range, 2.00-3.08 versus 4.05; interquartile range, 3.60-4.60; P<0.0001). Receiver operating characteristic analysis revealed postprocedural VFR >3.6 as the best threshold value for complete wound healing after EVT. Univariate analysis revealed that postprocedural VFR >3.6 was a predictor of wound healing (P=0.0002). CONCLUSIONS Advanced lower limb clinical setting may be caused by a poor capability of microvasculature. VFR, which is easily assessable, is useful in clinical risk stratification for patients with critical limb ischemia after EVT in the catheterization laboratory. CLINICAL TRIAL REGISTRATION URL: http://www.umin.ac.jp/ctr. Unique identifier: UMIN000009313.