Resting and Post-Exercise Ankle-Brachial Index Measurements to Diagnose Asymptomatic Peripheral Arterial Disease in Middle Aged and Elderly Chronic Obstructive Pulmonary Disease Patients: A Pilot Study

BACKGROUND: Chronic obstructive pulmonary disease (COPD) patients are at risk for asymptomatic peripheral arterial disease (PAD) because smoking is a risk factor for COPD and PAD. The objectives of this study were to determine the proportion of COPD patients with asymptomatic PAD and to investigate whether the estimated risk of asymptomatic PAD in subjects with COPD differs using resting and exercise ankle-brachial index (ABI) in smokers. METHODS: Using a cross-sectional study design, consecutive smokers > 50 years old were recruited over 2 months from the inpatient units and the outpatient clinics. Subjects previously diagnosed with PAD, unstable angina, recent (< 3 months) myocardial infarction or abdominal, intracranial, eye or lung surgery, and palliative care patients were excluded. Vascular risk factors, ABI (supine and post-3-minute walk supine), self-reported PAD symptoms, and spirometry were obtained. Two measurements of systolic blood pressure on all limbs were obtained using a sphygmomanometer and a Doppler ultrasound, and the ABI was calculated. Data were expressed as means ± standard deviation (SD). Dichotomous outcomes were assessed using Chi-square statistics; P-values of < 0.05 were considered significant. RESULTS: Thirty patients with no previous diagnosis of PAD were recruited. Mean age was 67.7 years (SD: 10.5). Overall, 21 subjects (70%) had spirometry-proven COPD. Significant ABI for PAD (< 0.9) was seen in 7/21 COPD (33.5%) and 0/9 non-COPD subjects in the supine resting position (P = 0.07), and in 9/21 COPD (42.9%) vs. 0/9 non-COPD subjects after exercise (P = 0.03). CONCLUSIONS: A significant proportion of patients with spirometry-proven COPD screened positive for asymptomatic PAD after exercise. Resting ABI may not be very sensitive to diagnose asymptomatic PAD in COPD subjects. ABI may be a reliable, sensitive and practical screening tool to assess cardiovascular risk in COPD patients. Future large-scale studies are required to confirm this finding.