Reactive myocardial hyperaemia for functional assessment of coronary stenosis severity.

Abstract

Our aim was to compare functional assessment of coronary stenosis severity by fractional flow reserve (FFR) measurement, as induced by systemic adenosine, and by regional reactive myocardial hyperaemia. The primary study endpoints were coronary pressure-derived FFR values in response to intravenous adenosine infusion (140 µg/min/kg), and to a one-minute proximal coronary artery balloon occlusion (reactive hyperaemia) for the same stenosis of interest. The secondary study endpoint was coronary collateral flow index (CFI) during the same occlusion. CFI is the ratio between simultaneous mean arterial occlusive pressure and mean aortic pressure, both subtracted by central venous pressure. As a reference, coronary artery stenoses were assessed quantitatively as percent diameter reduction (%S). One hundred and twenty-five patients with coronary artery disease were included in the study. There was an inverse association between quantitatively determined structural stenosis severity and adenosine-induced FFR as well as post-ischaemic reactive hyperaemia FFR (%S=1-0.004 FFR; both at p<0.0001). Sensitivity and specificity for detecting a stenosis of ≥50% at an FFR threshold of 0.80 was 0.891 and 0.605 (adenosine-induced FFR), and 0.817 and 0.684 (post-ischaemic FFR), respectively. The FFR difference for a given stenosis (post-ischaemic minus adenosine-induced FFR) was directly related to CFI. Regional reactive hyperaemia FFR is not inferior to systemic adenosine FFR in detecting structurally relevant coronary stenosis. Depending on the absence or presence of functional collaterals, systemic adenosine-induced FFR may underestimate or overestimate stenosis severity, respectively.