Tibial Artery Calcification as a Marker of Amputation Risk in Patients With Peripheral Arterial Disease

Abstract

The purpose of this study was to evaluate the relationship between calcification in tibial arteries, the degree of limb ischemia, and the near-term risk of amputation. Determining the amputation risk in patients with peripheral arterial disease (PAD) remains difficult. Developing new measures to identify patients who are at high risk for amputation would allow for targeted interventions and focused trials aimed at limb preservation. Two hundred twenty-nine patients underwent evaluation by history, arterial Doppler, and multislice computed tomography of the lower extremities. We then explored the relationship between a tibial artery calcification (TAC), traditional risk factors for PAD, limb status at presentation, and near-term amputation risk. Increased age and traditional atherosclerosis risk factors were associated with higher TAC scores. Patients with critical limb ischemia had the highest TAC scores, and increasing TAC scores were associated with worsening levels of limb ischemia in ordinal regression analysis. Receiver-operator characteristic analysis suggested that the TAC score predicted amputation better than the ankle-brachial index (ABI). Symptomatic patients with a TAC score greater than 400 had a significantly increased risk of amputation. In Cox regression analysis, there was a strong association between the TAC score and the risk of major amputation that remained after adjustment for traditional risk factors and the ABI. In patients presenting with PAD, the TAC score is associated with the stage of disease and it identifies those who are at high risk for amputation better than traditional risk factors and an abnormal ABI.