Assessment of FFR-negative intermediate coronary artery stenoses by spectral analysis of the radiofrequency intravascular ultrasound signal.
BACKGROUND
Assessing the clinical importance of angiographically intermediate coronary artery stenoses at the time of cardiac catheterization remains a challenge. Spectral analysis of radiofrequency ultrasound backscatter signals, or virtual histology (VH), allows in vivo assessment of plaque composition. This study characterizes the VH composition of fractional flow reserve (FFR)-negative intermediate stenoses and adjacent vessel segments.


METHODS
Intermediate coronary artery stenoses (> 40% and < 70% diameter stenosis) were assessed by pressure wire. If the FFR was > or = 0.75, percutaneous coronary intervention was deferred and VH was performed on the lesion and adjacent segments using a commercially available system. The primary clinical endpoint was any adverse cardiac event.


RESULTS
Thirty-seven intermediate stenoses in 30 patients were studied. The reference vessel size was 3.02 +/- 0.71 mm, the QCA diameter stenosis was 52 +/- 6% and the FFR was 0.89 +/- 0.07. The target stenoses were characterized by VH as: thin-cap fibroatheroma (VH-TCFA; n = 22); fibrous cap atheroma (n = 5), fibrocalcific lesion (n = 7) and pathological intimal thickening (n = 3). The relative contribution of each stenosis plaque component was conserved across adjacent segments ("signature" plaque). Three patients, all with VH-TCFAs at index, had events in the clinical follow-up period of 12 +/- 2 months, but only 1 of these patients had an event related to the index stenosis.


CONCLUSIONS
FFR-negative intermediate stenoses have heterogeneous plaque by VH, but are enriched in VH-TCFAs. Relative plaque composition is conserved along adjacent vessel segments. Although the specificity of VH-TCFA for index stenosis-related events appears low, larger trials are needed to assess the prognostic value of VH in this lesion subset.
Rogers
Jason H
JH
U.C. Davis Medical Center, Division of Cardiovascular Medicine, 4860 Y Street, Suite #2820, Sacramento, CA 95817, USA. jason.rogers@ucdmc.ucdavis.edu
Wegelin
Jacob
J
Harder
Kori
K
Valente
Richard
R
Low
Reginald
R
D000368:Aged; D003326:Coronary Circulation; D023921:Coronary Stenosis / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008297:Male; D008875:Middle Aged; D010865:Pilot Projects; D011846:Radio Waves; D012542:Scattering, Radiation; D018084:Ultrasonography, Interventional