0041: Contrast-induced microvascular dilatation: implications for fractional flow reserve measurements

BackgroundThe use of adenosine is sometimes considered as a limiting factor for of fractional flow reserve (FFR) measurements. The present study sought to quantify the potential of contrast medium (CM) to induce microvascular dilatation as assessed by the changes in Doppler flow velocity measurements.MethodsIn 30 patients, Doppler-derived flow velocity measurements were obtained in 10 right coronary arteries (RCA) and 20 left coronary arteries (LCA) free of significant stenosis. Flow velocity was measured at baseline and after 8mL intracoronary (IC) bolus administrations of arterial blood at body temperature, saline and CM compared to intracoronary boluses of adenosine at room temperature. The hyperemic value was expressed in percent of the maximum flow velocity reached in a given artery (Q/Qmax, %). To translate the IC adenosine dose into its effect on FFR, a model based on standard coronary physiology linked the degree of hyperemia to the relative distal coronary pressure (Pd/Pa).ResultsDoppler flow velocity varied among 8mL IC boluses of arterial blood, saline and contrast (p<0.001), and all pairwise comparisons were significant (p