IntroductionAnkle-brachial index (ABI) is an important indicator to diagnose lower extremity arterial disease (LEAD). However, patients with unmeasurable ABI are sometimes excluded from the analysis and their clinical characteristics are poorly understood.MethodsOne hundred twenty-two consecutive Japanese subjects (mean age, 72 years), who underwent successful endovascular treatment (EVT) for lower extremity arteries at our hospital were retrospectively studied.ResultsOf the 122 patients, 23 (19%) patients presented an unmeasurable ABI before EVT. Five of 23 (22%) had still an unmeasurable ABI one day after EVT. Comorbidities including hypertension, diabetes, dyslipidemia, hemodialysis, smoking, ischemic heart disease, atrial fibrillation, and past-EVT history were not different between ABI measurable and unmeasurable patients. However, patients with unmeasurable ABI presented a significantly higher degree of Rutherford category and a smaller number of tibial vessel runoff than patients with measurable ABI before EVT (p<0.05 and p<0.01, respectively). There was no difference in the lesion site between the two groups. The event rate including all-cause mortality, re-EVT, lower limb amputation, and bypass surgery did not differ between two groups four years after EVT. ABI after four years of initial EVT did not differ between pre-EVT measurable and unmeasurable patients (0.96 vs. 0.84, p=0.48).ConclusionsPatients with unmeasurable ABI before EVT were characterized by higher degree of Rutherford categorization and a small number of tibial vessel runoff, but there was no significant difference in outcomes during the follow-up period.