Heart rate-corrected ankle-to-arm index in the diagnosis of moderate lower extremity arterial disease.

Abstract

Although the ratio of ankle-to-arm systolic pressures (AAI) at rest is widely used in the clinical diagnosis of peripheral arterial disease, the heart rate (HR) at which the measurements are performed is rarely reported. The relation of ankle-to-arm index (AAI) to HR was studied in a normal population (n = 65) and in a population of patients (n = 101) suspected of moderate lower extremity arterial disease (LEAD). In the normal population, a significant inverse correlation was found between AAI and HR at rest: AAI = -0.277 x HR/100 + 1.303; r = -0.52, P < 0.001. In the second population suspected of LEAD, the authors recorded AAI and HR at rest on both legs; 80 normal legs, 110 diseased legs. Thereafter, with normal limits as superior to 0.8, 0.9, and 0.95, sensitivity was respectively 16, 39, and 46%, and specificity was 100, 100, and 98%. In defining normal limit as superior to -2 standard deviations of the AAI-HR relation found in the normal population, sensitivity and specificity were 57 and 100%, respectively. In screening for LEAD in the general population with the use of AAI at rest, the authors suggest that the heart rate at which arterial pressure measurements are performed should be reported.