128 Comparison between non invasive coronary flow reserve and fractional flow reserve in the setting of left anterior descending artery stenosis of intermediate severity

BackgroundThe functional significance of left anterior descending artery (LAD) stenosis of angiographic intermediate severity (IS) (50–70% diameter stenosis) is challenging.Objectiveto compare the value of non-invasive coronary flow reserve (CFR) to the invasive fractional flow reserve (FFR) in patients (pts) with LAD stenosis of IS.Methods46 consecutive pts (mean age 63±13 years, 11 females, mean LVEF 63±8%) with various risk factors (diabetes 17%, hypertension 52%, smoking 28%, dyslipidemia 74%), no previous anterior myocardial infarction, and with an LAD stenosis of IS (55±5% diameter stenosis, QCA) were prospectively studied. They underwent FFR with intracoronary bolus adenosine (150μg), 3 cms distal to the stenosis, and CFR using intravenous adenosine (140μg/kg/min over 2min), in the distal part of the LAD, the same day in nearly all cases. CFR was defined as hyperemic peak diastolic LAD flow velocity divided by baseline flow velocity (normal value≥2) and FFR was defined as distal pressure divided by mean aortic pressure during maximal hyperemia (normal value≥0.8).ResultsThe mean FFR and CFR were 0.84±0.07 and 2.8±0.7 respectively. Concordant results between FFR and CFR were seen in 39 cases (85%) and discordant results in 7 cases (15%). There was a weak correlation between CFR and FFR (r=0.43, p<0.01). A better correlation was found between FFR and LAD diameter stenosis (r=−0.42, p<0.01) than between CFR and LAD diameter stenosis (r=−0.23, p=0.1), and between FFR and lesion length (r=−0.39, p