786-2 Coronary Flow Reserve vs Transleslonal Velocity Gradient by Doppler Guidewire in Assessing Intermediate Coronary Stenoses

Abstract

Intracoronary Doppler guidewire measures of coronary flow reserve (CFR) and translesional velocity gradients (TVG) have been used to determine the physiologic significance of intermediate coronary lesions (40–70%). In many patients with intermediate stenoses CFR and TVG values are discordant, raising the possibility that CFR is diminished due to microvascular rather than epicardial disease. In 13 patients with an intermediate coronary lesion, we used an intracoronary Doppler guidewire to record baseline coronaryflowvelocity proximal and distal to each lesion, thus defining TVG. Peak hyperemic velocity was then recorded distally after an intracoronary bolus of adenosine to obtain CFR. All patients had decreased CFR (mean = 1.4 ± 0.3; normal ≥2.0) but trivial TVG (mean = 1.3 ± 0.3; normal <1.7). Each patient had a reversible perfusion defect on stress SPECT 201 TI imaging and subsequently underwent PTCA. These patients were asked to return at 6 months for a repeat stress SPECT201 TI test. Two patients had restenosis prior to repeat stress testing. The remaining 11 patients had their baseline and 6 month post-PTCA scans analyzed. Region of Interest201 TI Ouantitation (counts as % of normal) Pre-PTCA Stress 77 ± 2.5 Post-PTCA Stress 89 ± 3.0 * Delay 93 ± 3.0 * Delay 93 ± 4.0 P(ANOVA) < 0.0001 * p < 0.05 vs Pre-PTCA Stress All 11 patients demonstrated qualitative normalization of SPECT 201 TI scans at 6 month follow-up. Ouantitative polar mapping and region of interest analysis confirmed the improvement in perfusion. Therefore, blunted CFR was related to a physiologically significant intermediate stenosis rather than a microvascular cause. It appears that CFR is a more reliable indicator of lesion significance than TVG.