Relation Between Vascular Resistance and Intimal Thickness in Patients with Coronary Artery Disease

ABSTRACT

BACKGROUND: The intimal thickening of coronary artery was understood as an early process in the beginning of atherosclerosis. However, the implication of intimal thickening as a morphologic change of coronary artery disease, on the coronary vascular hemodynamics has not been explored. METHODS: To evaluate the effect of intimal thickening on the coronary vascular hemodynamics, we studied the extent of intimal thickening on intravascular ultrasound(IVUS) and the coronary vascular flow and resistance by using Doppler wire in left anterior descending coronary arteries after successful intervention in 40 patients(29 males, mean age 55+/-9 years) with coronary artery disease. Mean intimal index and mean lumen cross sectional area were determined by IVUS and coronary flow average peak velocity was obtained by using Doppler wire before and after intracoronary adenosine in distal artery to the stenosis. Coronary flow velocity reserve(CFR), volumetric coronary blood flow(CBF) and coronary vascular resistance index(CVRI) were calculated. Hyperemic pressure-to-flow ratio(hyperemic mean aortic pressure/hyperemic volumetric coronary blood flow), ie, an index of minimal coronary vascular resistance(mCVR), was further derived. RESULTS: Intimal index(mean 20.0+/-8.3%) was significantly correlated with CVRI(mean 0.33+/-0.14, r=.37, p=.02) and mCVR(mean 0.81+/-0.40mmHg/ml/min, r=.36, p=.02). However, there was no correlation with CBF and CFR. CONCLUSION: The CVRI and mCVR(hyperemic pressure to flow ratio), the indices coronary microvascular resistance, were significantly related to the degree of intimal thickness of coronary artery. The extent of intimal thickness of coronary artery on IVUS study may be related to microvascular integrity.