Introductions: Fractional flow reserve (FFR) that was tested by the pressure wire has been recently a reliable physiological evaluation of ischemic status on coronary artery stenosis. However, microcirculatory function on FFR could not been distinguished by this pressure-monitoring system. We aimed to estimate vasodilating function in distal coronary capillaries by evaluating the time required to achieve hyperemia in patients with coronary artery disease.
Methods: Of 3,117 consecutive patients who underwent coronary angiography, 222 patients with angiographically intermediate coronary stenoses who were measured FFR were ultimately enrolled in this study. The time between the initial descent point of distal coronary pressure/aortic pressure (Pd/Pa) and the minimal point of Pd/Pa (FFR) (Drop to Peak time: D-P time, Figure 1) was measured. Hyperemia was induced by 150 ug/kg/min of intravenous ATP administration.
Results: Among diverse parameters tested, flow-mediated dilation (FMD) had a positive correlation with D-P time (r=0.19, p=0.007, Figure 2), and FMD was dramatically stepped-up at 40 seconds of D-P time. Based on this result, we divided all enrolled patients into 2 groups by D-P time with cut-off value of 40 seconds. Long D-P group had significantly lower body mass index, end-diastolic left ventricular (LV) diameter and LV mass index, and longer lesion length. Long D-P group also included a higher rate of lesions that achieved positive FFR (<0.8) (46% vs. 27%, p=0.019), even %diameter stenosis or distribution of target lesion was not significantly different between the groups. Multivariate logistic regression analysis revealed that Long D-P time independently had a positive association with FMD (Odds ratio: 3.61, 95%Confidence interval: 1.40-9.34).
Conculusions: Time between the descent point and negative peak of Pd/Pa was associated with FMD. This new parameter may reflect vasodilation in distal coronary arteries.