R Eugene Zierler1, Kirk W. Beach1, Robert O. Bergelin1, Brajesh K. Lal2, Wesley S. Moore3, Gary S. Roubin4, George Howard5, Jenifer H. Voeks6, Thomas G. Brott7
1D. E. Strandness, Jr. Vascular Laboratory, University of Washington, Seattle, WA; 2University of Maryland Medical School, Baltimore, MD; 3University of California Los Angeles, Los Angeles, CA; 4Continuum Cardiovascular Centers of New York, New York, NY; 5University of Alabama at Birmingham, Birmingham, AL; 6Medical University of South Carolina, Charleston, SC; 7Mayo Clinic, Jacksonville, FL.
OBJECTIVES: Patients in CREST had duplex ultrasound (DU) scans prior to treatment (PRE) and during follow-up (FU) to document the severity of carotid disease and the outcome of endarterectomy (CEA) or stenting (CAS). An ultrasound core laboratory (UCL) reviewed DU data from the clinical sites. This analysis was done to determine the agreement between site-reported and UCL-verified DU velocity measurements.
METHODS: Clinical site DU worksheets and images for the treated carotid arteries were reviewed at the UCL. The highest internal carotid artery peak systolic velocity (PSV) and associated Doppler angle were verified. If the angle was misaligned by >3 degrees, it was re-measured and PSV recalculated. Agreement for PSV was defined as site-reported PSV within ±5% of UCL-verified PSV. Transcription errors were corrected by the UCL but were not considered as disagreements. FU analysis was limited to patients who received the assigned treatment.
RESULTS: The UCL reviewed 1,702 PRE and 1743 12-month FU DU scans (873 CEA, 870 CAS) from 111 clinical sites. Site-reported and UCL-verified velocity measurements agreed in 66% of PRE scans and 69% of FU scans. In those cases with a disagreement, Doppler angle accounted for disagreement in 59% of PRE scans and 51% of FU scans. Based on a threshold PSV for ≥70% stenosis of ≥230cm/s on the PRE scans and ≥300cm/s on the FU scans, UCL review resulted in reclassification of stenosis severity in 75 (4.4%) of the PRE scans and 13 (0.75%) of the FU scans. The proportion of reclassification at FU was greater for CAS (1.2%) than for CEA (0.34%) scans (p=0.051).
CONCLUSIONS: There was a high rate of agreement between site-reported and UCL-verified DU results and a low rate of stenosis reclassification in CREST. However, angle errors were quite common and prompted recalculation of velocity in 20% of PRE scans and 18% of FU scans. The use of a UCL provides a uniform process for DU interpretation and can identify sources of error and suggest technical improvements for future studies.
AUTHOR DISCLOSURES: K. W. Beach: Nothing to disclose; R. O. Bergelin: Nothing to disclose; T. G. Brott: Nothing to disclose; G. Howard: Federal Funding from NIH, Research Grants; Consultant to Abbott Vascular for preparation of FDA materials, Consulting fees or other remuneration (payment); B. K. Lal: Nothing to disclose; W. S. Moore: Nothing to disclose; G. S. Roubin: Abbott Vascular, Consulting fees or other remuneration (payment); Cook Medical, Consulting fees or other remuneration (payment); Medicines Co., Consulting fees or other remuneration (payment); Essential Medical, Ownership or partnership; J. H. Voeks: Nothing to disclose; R. Zierler: Nothing to disclose.
Posted April 2013