Colchicine in Chronic Limb-Threatening Ischemia

Chronic limb-threatening ischemia (CLTI) is the most severe form of peripheral artery disease, a condition in which narrowed or blocked arteries reduce blood flow to the legs. People with CLTI may have severe leg pain at rest, non-healing wounds, or gangrene, and face a high risk of leg amputation and death. Even after successful procedures to restore blood flow to the leg (called revascularization), many patients still experience serious complications. Inflammation in the blood vessels is believed to play an important role in these poor outcomes. Colchicine is an anti-inflammatory medication that has been used safely for decades to treat gout and other inflammatory conditions. Recent large clinical trials have shown that a low dose of colchicine (0.5 mg per day) can reduce heart attacks and strokes in patients with coronary artery disease. However, it has not been studied in patients with CLTI. The CIRCLE-Asia trial (Colchicine in Chronic Limb-Threatening Ischemia for Reduction of Complications and Limb Events in Asia) is a pilot study designed to evaluate whether colchicine can improve outcomes in patients with CLTI who have recently undergone a successful procedure to restore blood flow to their leg. Treatment begins within 7 days of the procedure. This is a randomized, double-blind, placebo-controlled, multicenter trial conducted at five hospitals in Taiwan. A total of 200 adult patients with CLTI who have undergone successful revascularization will be randomly assigned in a 1:1 ratio to receive either colchicine 0.5 mg once daily or a matching placebo pill, in addition to their usual medications, for 12 months. Neither the patients nor the study doctors will know which treatment each patient receives. The main outcome of interest is amputation-free survival, defined as the time until major amputation of the affected leg (above the ankle) or death from any cause, over 12 months of follow-up. The study will also assess other important outcomes including major limb complications, heart attacks, strokes, wound healing, changes in blood flow measurements, inflammatory blood markers, quality of life, and medication safety. This pilot trial will provide the first randomized evidence on the potential benefits and safety of colchicine in CLTI patients and will help inform the design of a larger definitive trial.

Inclusion Criteria: 1. Age ≥18 years. 2. Documented chronic limb-threatening ischemia, meeting the following: * Presence of ischemic symptoms compatible with CLTI, defined as arterial insufficiency with gangrene, non-healing ischemic ulcer, or rest pain consistent with Rutherford classes 4-5 AND * Imaging evidence within the past 12 months showing atherosclerotic PAD, including CTA, MRA, angiography or duplex ultrasound AND * Ankle-Brachial Index (ABI) ≤0.80 or Toe-Brachial Index (TBI) ≤0.60 for patients without prior revascularization; ABI ≤0.85 or TBI ≤0.65 for those with prior revascularization OR * Ischemic rest pain alone (Rutherford class 4) defined as ankle systolic pressure \