Relation of brachial artery flow-mediated vasodilation to significant coronary artery disease in patients with peripheral arterial disease.

In patients at risk for coronary atherosclerosis, brachial artery flow-mediated dilation (FMD) rules out significant coronary artery disease (CAD). However, the value of this approach is unknown in patients with peripheral arterial disease who are at increased risk for CAD. This study assessed whether the noninvasive evaluation of endothelial function by brachial artery FMD rules out significant CAD by dipyridamole myocardial perfusion imaging (MPI) in patients with peripheral arterial disease who are asymptomatic for CAD. Forty-four patients with peripheral arterial disease who were asymptomatic for CAD underwent, in the same day, FMD evaluation and dipyridamole MPI using technetium-99m sestamibi single photon-emission computed tomography. MPI results were abnormal in 17 of 44 patients (39%). FMD was significantly less (6.0 +/- 2.3%) in patients with abnormal MPI results compared with those with normal MPI results (7.3 +/- 1.8%, p = 0.04). By multivariate analysis, FMD was the only significant predictor of abnormal MPI results (odds ratio 0.63, p = 0.02). Receiver-operating characteristic curve analysis assessing the ability of FMD to identify patients with summed stress scores > or =3 yielded an area under the curve of 0.74 (p = 0.009). A FMD value >6% provided 92% negative predictive power to rule out abnormal MPI results, with sensitivity of 79% and specificity of 73%. In conclusion, the noninvasive evaluation of endothelial function by FMD has high negative predictive accuracy and good sensitivity and specificity to detect abnormal MPI results in patients with peripheral arterial disease. Thus, it may represent a valuable screening test to rule out significant CAD in these patients.

The identification of reversible dysfunctional myocardium is influenced by the severity of contractile dysfunction and by the length of follow-up.

OBJECTIVES: To evaluate the influence of the severity of regional myocardial dysfunction and of the length of follow-up on the identification of myocardial viability with rest-redistribution Tl single photon emission computed tomography (SPECT) and low-dose dobutamine echocardiography (LDDE). METHODS: Twenty-six patients with chronic coronary artery disease and wall motion abnormalities, candidates for revascularization, were included in this study. All patients underwent, in the same week, Tl SPECT and LDDE for pre-revascularization evaluation of myocardial viability. Reversibility of regional dysfunction was assessed by two-dimensional echocardiography, 40+/-20 days (early follow-up) and 12+/-5 months (late follow-up) after revascularization. RESULTS: In a/dyskinetic segments, Tl SPECT showed similar values of sensitivity (78% vs. 71%, P=NS) and slightly higher values of specificity (43% vs. 18%, P<0.01) compared to hypokinetic segments, in predicting functional recovery at early follow-up. No significant changes were observed in the diagnostic accuracy of Tl SPECT at late follow-up. On the contrary, LDDE provided significantly lower values of sensitivity (56% vs. 94%, P<0.05) and higher values of specificity (73% vs. 9%, P<0.01) in a/dyskinetic compared to hypokinetic segments. Specificity of LDDE in a/dyskinetic segments significantly increased from early (73%) to late follow-up (95%; P<0.05). Similarly, positive predictive value in a/dyskinetic segments significantly increased from early (69%) to late follow-up (96%; P<0.05). CONCLUSIONS: The severity of regional dysfunction and the length of follow-up significantly influence the diagnostic accuracy of LDDE but not of rest-redistribution Tl SPECT in the identification of myocardial viability.