Relationship between brachial artery flow-mediated dilation and coronary flow reserve in patients with peripheral artery disease

The aim of this study was to assess the relationship between brachial artery flow-mediated dilation (FMD) and coronary flow reserve (CFR) in patients with peripheral artery disease (PAD). Methods: Thirty patients who had PAD, who showed no cardiac symptoms, and who had normal stress SPECT cardiac imaging results and 28 control subjects underwent brachial artery FMD assessment by ultrasound and dipyridamole Tc-99m-sestamibi imaging. Myocardial blood flow (MBF) was estimated by measuring first-transit counts in the pulmonary artery and myocardial counts from SPECT images. Estimated CFR was expressed as the ratio of MBF at stress to MBF at rest. Results: Patients with PAD were separated into 2 groups according to the median value of overall FMD (6.85%): group 1 (n = 15) with FMD above the median (mean +/- SD, 8.78% +/- 1.3%) and group 2 (n = 15) with FMD below the median (mean +/- SD, 5.14% +/- 0.94%). FMD was significantly higher in control subjects (11.4% +/- 3.4%) than in both groups of PAD patients (P < 0.001 for both). In control subjects, estimated CFR was 2.2 +/- 0.4-significantly higher than CFR in both groups of PAD patients (P < 0.001 for both). In addition, in PAD patients of group 1, estimated CFR was 1.5 +/- 0.4-higher than CFR in group 2 (1.0 +/- 0.4) (P < 0.01). When all PAD patients were considered, a significant correlation between FMD and estimated CFR was observed (r = 0.56, P < 0.005). Conclusion: Estimated CFR is significantly lower in patients with PAD than in control subjects, and CFR impairment correlates with the degree of peripheral endothelial dysfunction.