Purpose. By convention when recording the ankle-brachial index (ABI) in the investigation of lower extremity peripheral arterial disease (PAD), the highest ABI is reported. For each lower extremity there are two arterial ABI measurements, one for the dorsalis pedis (DP) artery and the other for the posterior tibial (PT) artery. An abnormal ABI as conventionally reported correlates well with the presence of a lower extremity peripheral arterial stenosis of >50%. While this approach is clinically proven and generally accepted we feel it reduces the potential of the test to detect any PAD. The purpose of our study was to assess the frequency of an abnormal ABI in either the DP or PT vessel in patients with a conventionally normal ABI in the other DP or PT vessel.
Methods. We have performed peripheral physiologic leg testing in 720 patients. 185 patients (25.7%) had at least one abnormal ABI of 0.94 in both legs. This represents the highest ABI recorded from either the DP or PT arteries. 523 patients had all 4 ABIs recorded namely DP and PT ABI in both legs. These patients were used in this analysis. All data were entered into CARDIOfile, a cardiology database, for later retrieval and analysis.
Results. See table 1.
Conclusions. Conventionally when performing the ankle-brachial index the highest ABI from either the DP or PT is reported. This is clearly useful for the vascular surgeon who is looking for hemodynamically significant surgical PAD. However for physicians involved in vascular prevention our data would suggest that 13% of patients with PAD in either the DT or PT territories will be overlooked. It is our recommendation that both the DP and PT values for the ABI be recorded and reported. When one or other is abnormal the test should be reported as abnormal.