Abstract 16385: A Pitfall of Fractional Flow Reserve Measurement in the Left Anterior Descending Coronary Artery: A Gradual Decrease of Coronary Pressure
Background: In the presence of a similar degree of moderate stenosis in coronary arteries, FFR in the left anterior descending (LAD) is frequently lower than that in the other arteries. We validated the hypothesis that there is no decline of coronary pressure from the proximal to distal part in the LAD.
Methods: Twenty-six patients with normal coronary angiogram in the LAD without signs of anterior wall ischemia were enrolled. A pressure sensor was placed in multiple points of the LAD and an FFR (mean distal/proximal pressures at hyperemia) was measured at each points: 12, 10, 7, and 5cm distal to the ostium, and the ostium. Intravascular ultrasound (IVUS) and right-heart catheterization were performed. Blood sample was obtained from the aortic-root and the anterior interventricular vein to calculate myocardial oxygen uptake (MVo2). The Romhilt-Estes score on electrocardiogram was calculated using scores of 4 points for the diagnosis of left ventricular hypertrophy (LVH).
Results: The FFR did not indicate 1.0 in any case at any location in the LAD. In all patients, FFR decreased gradually in proportion to distance from the ostium (average: 0.85±0.06 at 12 cm distal to the ostium). No difference was identified in the degree of degradation of FFR between patients without the evidence of any plaque on IVUS and patients with the evidence of minor plaque (left figure). The right-heart catheterization parameters, MVo2, myocardial bridge on IVUS, and ejection fraction were not correlated with the degree of degradation of FFR. However, the degradation degree of FFR was significantly larger in patients with LVH than in patients without LVH (right figure).
Conclusions: Coronary pressure gradually decreases in proportion to distance from the ostium in the LAD regardless of the presence of minor atherosclerotic plaque. The degradation degree of FFR is enlarged if the electrocardiogram indicates LVH. Our data suggests that FFR measurement could overestimate stenosis severity in the LAD.
- © 2012 by American Heart Association, Inc.