End-diastolic fractional flow reserve: comparison with conventional full-cardiac cycle fractional flow reserve.
BACKGROUND
Diastolic fractional flow reserve (dFFR) has been shown to be highly sensitive for detection of inducible myocardial ischemia. However, its reliance on measurement of left-ventricular pressure for zero-flow pressure correction, as well as manual extraction of the diastolic interval, has been its major limitation. Given previous reports of minimal zero-flow pressure at end-diastole, we compared instantaneous ECG-gated end-diastolic FFR with conventional full-cardiac cycle FFR and other diastolic indices in the porcine model.


RESULTS
Measurements of FFR in the left anterior descending and left circumflex arteries were performed in an open-chest swine model with an external occluder device on the coronary artery used to produce varying degrees of epicardial stenosis. An ultrasound flow-probe that was placed proximal to the occluder measured absolute blood flow in ml/min, and it was used as a gold standard for FFR measurement. A total of 17 measurements at maximal hyperemia were acquired in 5 animals. Correlation coefficient between conventional mean hyperemic FFR with pressure-wire and directly measured FFR with flow-probe was 0.876 (standard error estimate=0.069; P<0.0001). The hyperemic end-diastolic FFR with pressure-wire correlated better with FFR measured directly with flow-probe (r=0.941, standard error estimate=0.050; P<0.0001).


CONCLUSIONS
Instantaneous hyperemic ECG-gated FFR acquired at end-diastole, as compared with conventional full-cardiac cycle FFR, has an improved correlation with FFR measured directly with ultrasound flow-probe.
From the Department of Radiological Sciences, University of California-Irvine, Irvine, CA (D.A.C., Z.Z., S.M.); Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA (D.A.C.); Department of Radiology, Tianjin Medical University General Hospital, Tianjin, China (Z.Z.); Division of Cardiology, University of California-Irvine, Orange, CA (S.T.).
David A
DA
Chalyan
Zhang
Z
Zhang
Shigeho
S
Takarada
Sabee
S
Molloi
D000818:Animals; D001013:Aorta, Thoracic / Q000000981:diagnostic imaging; D023921:Coronary Stenosis / Q000000981:diagnostic imaging; D004562:Electrocardiography; D053805:Fractional Flow Reserve, Myocardial / Q000502:physiology; D006352:Heart Ventricles / Q000000981:diagnostic imaging*; D006439:Hemodynamics / Q000502:physiology; D006801:Humans; D006940:Hyperemia / Q000175:diagnosis*; D023421:Models, Animal; D017202:Myocardial Ischemia / Q000175:diagnosis*; D011859:Radiography; D013318:Stroke Volume; D013552:Swine; D019616:Thoracic Surgical Procedures; D014463:Ultrasonography
constriction, pathologic; coronary artery disease; fractional flow reserve, myocardial; hemodynamics; ischemia