Long-term outcomes of large artery thromboangiitis obliterans and comparison with small artery thromboangiitis obliterans

Although the distribution of arterial involvement is still the subject of controversy for defining the diagnostic criteria for thromboangiitis obliterans (TAO), several reports have described TAO involving the more proximal arterial segment. This study aimed to investigate the clinical characteristics and outcomes of large artery TAO in comparison with those of small artery TAO. Between January 2007 and July 2019, 83 consecutive symptomatic patients with a diagnosis of lower extremity TAO were stratified according to the most proximal arterial involvement, with the cutoff level of the adductor canal as a reference (large artery TAO versus small artery TAO), and analyzed retrospectively. The study outcomes included any amputations and major amputations. The large artery TAO group consisted of 30 patients (36.1%), and the small artery TAO group consisted of 53 patients (63.9%). In terms of clinical symptoms and signs, the proportion of major tissue loss (Rutherford class 6) was significantly higher among patients with large artery TAO than among those with small artery TAO (13.3% versus 0%, P = .02). Any amputation rate was similar between the large and small artery TAO groups during the median follow-up period of 148 months (range, 0-376 months) (43.3% versus 28.3%, P = .16). However, the major amputation rate was significantly higher among patients with large artery TAO (13.3% versus 0%, P = .02). On Kaplan-Meier survival analysis of the cumulative event-free rates, although there was a similar 10-year amputation-free survival rate (P = .24) between the 2 groups, the large artery TAO group had a significantly lower 10-year major amputation-free survival rate (P < .01) than the small artery TAO group. Large artery TAO is a limb-threatening condition and had a worse prognosis than small artery TAO.