Severity of Peripheral Arterial Disease is Associated With Aortic Pressure Augmentation and Subendocardial Viability Ratio

J Clin Hypertens (Greenwich). 2012; 14:855–860. ©2012 Wiley Periodicals, Inc.Peripheral arterial disease (PAD) is associated with increased cardiovascular mortality that correlates with peripheral perfusion impairment as assessed by the ankle‐brachial arterial pressure index (ABI). Furthermore, PAD is associated with arterial stiffness and elevated aortic augmentation index (AIx). The purpose of this study was to investigate whether ABI impairment correlates with AIx and subendocardial viability ratio (SEVR), a measure of cardiac perfusion during diastole. AIx and SEVR were assessed by radial applanation tonometry in 65 patients with stable PAD (Rutherford stage I–III) at a tertiary referral center. AIx corrected for heart rate and SEVR were tested in a multivariate linear and logistic regression model to determine the association with ABI. Mean ABI was 0.8±0.2, AIx 31%±7%, and SEVR 141%±26%. Multiple linear regression with AIx as a dependent variable revealed that AIx was significantly negatively associated with ABI (β=−11.5; 95% confidence interval [CI], −18.6 to −4.5; P=.002). Other variables that were associated with AIx were diastolic blood pressure (β=0.2; 95% CI, 0.1–0.4; P<.001), height (β=−46.2; 95% CI, −62.9 to −29.4; P<.001), body mass index (β=−0.4; 95% CI, −0.8 to −0.1; P=.023), and smoking (β=3.6; 95% CI, 0.6–6.6; P=.019). Multiple regression with SEVR as a dependent variable showed a significant correlation with ABI (β=33.2; 95% CI, 2.3–64.1; P=.036). Severity of lower limb perfusion impairment is related to central aortic pressure augmentation and to subendocardial viability ratio. This may be a potential pathophysiologic link that impacts cardiac prognosis in patients with PAD.

Peripheral arterial disease (PAD) is a common manifestation of atherosclerosis that affects more than 5% of the aged population. ¹ , ² PAD is associated with impairment in functional activity and with an increased risk of cardiovascular events. ³ , ⁴ For this reason, PAD is considered a marker for systemic atherosclerosis. ⁵ To date, the most powerful prognostic indicator in PAD patients is the ankle‐brachial arterial pressure index (ABI). ⁶ , ⁷ , ⁸ ABI is a measure to define impairment of lower limb perfusion that has been shown to predict survival rate in patients with PAD. ¹ , ⁹ , ¹⁰ The mechanisms through which the presence of PAD increases this risk are not understood in detail. PAD represents a vascular disease with extensive atherosclerotic involvement. Systemic inflammation and increased levels of oxidative stress parallel this. Both are known to destabilize atherosclerotic plaque and thus may be associated with vascular events. ¹¹ In addition, the extensive atherosclerotic alterations along the vascular tree conduit are thought to increase pulse wave velocity, and lower limb arterial obstructions may favor premature pulse wave reflections. ¹² , ¹³ Khaleghi and colleagues ¹² reported significant differences in augmentation index (AIx) between subjects with normal and abnormal ABI. Furthermore, an association between ABI and the degree of subendocardial viability ratio (SEVR) impairment in patients with type 1 diabetes has been reported. ¹⁴ A recent publication by Rabkin and colleagues ¹⁵ describes an association between ABI and AIx in patients without PAD. Given that, we assume that ABI impairment might be associated with AIx and SEVR.We therefore tested whether degree of ABI impairment is related to an increased AIx and decreased SVER as assessed noninvasively by radial pulse wave analysis in patients with stable PAD.