"The tibial artery calcification (TAC) score, assessed by multidetector CT, can identify patients with peripheral arterial disease (PAD) who are at high risk for amputation, new research shows. In fact, in this regard, the TAC score is superior to traditional risk factors and an abnormal ankle-brachial index.

Predicting which patients are likely to require amputation is difficult, but important, in determining the appropriate therapeutic intervention, Dr. Raul J. Guzman, from Vanderbilt University Medical Center in Nashville, Tennessee, and colleagues write in the Journal of the American College of Cardiology for May 20.

In their study, the research team evaluated 118 patients with symptomatic PAD and 111 community volunteers without symptomatic PAD, using arterial Doppler and multislice CT of the lower extremities. Higher TAC scores correlated with increased age and with traditional atherosclerosis risk factors, the researchers found. The highest scores were seen in patients with critical limb ischemia.

During a mean follow-up of 13.8 months, 28 amputations were performed in the vascular group while none were needed in the control group.

Analysis of receiver-operator characteristic curves suggested that the TAC score was a better predictor of amputation than was the ankle-brachial index. In particular, the authors found that a TAC score above 400 in the setting of ischemic symptoms identified patients at high risk for amputation.

Even after accounting for traditional risk factors and the ankle-brachial index, a strong link between TAC score and amputation risk was seen, the report indicates.

Whether the TAC score will prove useful and should be incorporated into clinical practice remains to be determined, Dr. Andrew J. Feiring, from Columbia St.-Mary's Hospital in Milwaukee, comments in an accompanying editorial. "However, as with all compelling studies, this one raises more questions than it answers and illuminates an area of clinical confusion and frustration."