Abstract 1749: Possible Link between Large Artery Stiffness and Coronary Flow Velocity Reserve
Background: Population studies have shown that increased large artery stiffness is an independent predictor of cardiovascular events. As the aorta stiffens, the velocity of the pressure wave increases, and the reflected pressure wave eventually reaches the heart during systole rather than diastole. Consequently, the diminished elasticity of the stiff aorta, combined with the absence of diastolic augmentation from the reflected pressure wave, has the potential to reduce coronary perfusion pressure and coronary blood flow. Experimental studies have shown that a stiff aorta is associated with decreased coronary blood flow. However, a link between large artery stiffness and coronary microvascular function in the clinical setting has not been fully demonstrated previously. The aim of this study was to evaluate the relationship between large artery stiffness and coronary flow velocity reserve (CFVR).
Methods: The study enrolled 102 consecutive subjects (mean age 62 ± 10) without coronary and peripheral arterial disease. After 15 min of rest, measurements were obtained of brachial-ankle pulse wave velocity (baPWV), augmentation index (AIx) from a carotid pulse tracing, and transthoracic echocardiographic parameters, including coronary flow velocity in the left anterior descending coronary artery. In addition, coronary flow velocity during hyperemia was measured during an intravenous infusion of adenosine triphosphate (0.14 mg/kg/min). CFVR was defined as the ratio of hyperemic to basal coronary velocity.
Results: Subjects with decreased CFVR (<2.5; n = 40) had significantly higher baPWV (1848 ± 360 cm/sec vs. 1548 ± 333 cm/sec, P<0.0001), greater AIx (25 ± 11 % vs. 16 ± 20 %, P<0.05) and greater pulse pressure (PP) (64 ± 13 mmHg vs. 54 ± 13 mmHg, P<0.001) than those with normal CFVR (n = 62). Multivariate analysis among age, gender, hemodynamic parameters, metabolic variables, left ventricular mass index, E/A ratio, baPWV and AIx revealed that AIx and PP were independent predictors of CFVR (r = −0.32, P<0.0001 and −0.25, P<0.05, respectively).
Conclusions: Our data suggest that high AIx and PP are linked to a reduction of coronary flow velocity reserve, which may partially explain the higher cardiac event rate in patients with increased large artery stiffness.