This article is more than 5 years old. Information may no longer be current.
FIRST: Anatomic measurements by IVUS show moderate correlation with FFR
New data from the FIRST study suggest that there is a moderate correlation between anatomic measurements of intermediate coronary lesions obtained by intravascular ultrasound and those obtained by fractional flow reserve.
The results, published in the Journal of the American College of Cardiology, suggest that the optimal cutoff for minimum lumen area to fractional flow reserve (FFR) <0.8 is vessel dependent. “Different minimum lumen area cutoffs should be used for different vessel sizes,” Ron Waksman, MD, from MedStar Washington Hospital Center, Washington, D.C., and colleagues wrote.
The prospective, international FIRST registry was designed to determine the optimal minimum lumen area by IVUS that correlates with FFR and to ascertain the connection between virtual histology IVUS and FFR for intermediate coronary lesions, according to the study abstract. Researchers enrolled 350 patients with 367 lesions. For the study, intermediate coronary lesions were defined as 40% to 80% stenosis by angiography.
Researchers determined a minimum lumen area <3.07 mm2 was the best threshold value for the identification of FFR <0.8. This value had 64% sensitivity, 64.9% specificity. When vessel-specific analyses were performed, accuracy improved.
For reference vessel diameters <3 mm, a minimum lumen area <2.4 mm2 was identified as the best threshold value; for diameters of 3 mm to 3.5 mm, a minimum lumen area <2.7 mm2 was best; and for diameters >3.5 mm, a minimum lumen area <3.6 mm2 was best.The researchers found a correlation between plaque burden and FFR (r=–0.220; P<.001), but no correlation with other plaque morphology.
“The utility of IVUS minimum lumen area as an alternative to FFR to guide intervention in intermediate lesions may be limited in accuracy and should be confirmed clinically,” Waksman and colleagues concluded.
For more information:
Waksman R. J Am Coll Cardiol. 2013;doi:10.1016/j.jacc.2012.12.012.
Disclosure: The study was funded by Volcano Corporation. Waksman reports no relevant financial disclosures.
Perspective
Back to Top
The FIRST study points out the limitations of IVUS and, since there are so little clinical trial data concerning IVUS and stenting (appropriately), it makes the use of IVUS as a sole arbiter in stenting suspect. Clearly, we need a clinical trial to further elucidate what role IVUS plays in stenting, aside from the well-studied use in left main and proximal right coronary disease, as well for stent apposition, vascular morphology and so on.