Purpose: To report the 12-month follow-up data from the prospective 16-center Below-the-Knee (BTK) Chill Trial, which examined the use of primary cryoplasty for BTK occlusive disease in patients with critical limb ischemia (CLI).
Methods: The trial included 108 patients (77 men; mean age 73 +/- 11 years, range 41-101) with CLI (Rutherford categories 4-6) involving 111 limbs with 115 target infrapopliteal lesions. Angiographic inclusion criteria were reference vessel diameter > or = 2.5 mm and < or = 5.0 mm and target lesion stenosis > or = 50%. The primary study endpoints were acute technical success (the ability to achieve < or = 50% residual stenosis and continuous inline flow to the foot) and absence of major amputation of the target limb at 6 months. Secondary endpoints were serious adverse events specifically related to use of primary cryoplasty and absence of major amputation of the target limb at 1, 3, and 12 months.
Results: Acute technical success was achieved in 108 (97.3%) of treated limbs, with only 1 clinically significant dissection (> or = type C) and 2 residual stenoses >50%; stent placement was required following cryoplasty in only 3 (2.7%) procedures. At 6 months and 1 year, major amputation was avoided in 93.4% (85/91) and 85.2% (69/81) of patients, respectively. Through 1 year, 21% (17/81) of patients underwent target limb revascularization. Rates of major amputation and death at 1 year were 0% for limbs of patients with initial Rutherford category 4; 11.4% and 0%, respectively, for initial category 5; and 40.0% and 31.8% for initial category 6. One-year rates of major amputation and death were 20.4% and 8.8%, respectively, for diabetics, versus 4.0% and 10.7% for non-diabetics. At 1 year, major amputation occurred in 16.7% (2/12) of limbs that were expected to be amputated at the time of treatment.
Conclusion: Cryoplasty therapy is a safe and effective method of treating infrapopliteal disease, providing excellent results and a high rate of limb salvage in patients with CLI. Study outcomes through 1 year support the use of cryoplasty as a primary treatment option for patients with CLI secondary to BTK occlusive disease.