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This article was originally published in The Gray Sheet

Executive Summary

CVIS' CORONARY IMAGING CATHETER USE INFLUENCES TREATMENT APPROACH in 44% of cases investigated in a 136 patient study presented March 16 at the American College of Cardiology annual meeting in Anaheim, California. The 15-center prospective study was conducted by William Mullen, MD, et al., University of California at San Francisco and Stanford University Hospital, Palo Alto, California, to assess the impact of intravascular ultrasound in guiding interventional treatment with percutaneous transluminal coronary angioplasty (PTCA) and directional coronary atherectomy (DCA). The study, Phase I of the Guidance by Ultrasound Imaging for Decision Endpoints (or GUIDE) trial, evaluated 136 patients undergoing either PTCA or DCA who gave informed consent for intravascular ultrasound imaging. The imaging was performed using Sunnyvale, California-based Cardiovascular Imaging Systems, Inc.'s 4.3 French coronary catheter, which has been on the market since 1991. CVIS provided financial support for the trial. Throughout PTCA or DCA treatment, lesion assessments and therapeutic approach selections were recorded at key decision points following angiograms. After preliminary treatment decisions were made based on angiogram results, intravascular ultrasound imaging was performed, and any changes in assessments and therapeutic approach selections were recorded. Based on the ultrasound image, in 92 of 136 patients (68%), a significant change in the assessment of a lesion was made at at least one decision point. In 60 patients (44%), a change in therapeutic approach was made due to the information provided by ultrasound. The changes in therapeutic approach made following intravascular ultrasound in patients originally undergoing PTCA included further inflation of a balloon in 22% of the cases, use of a larger balloon in 54% of the cases, use of a perfusion balloon in 16% of the cases, termination of the procedure in 10% of the cases, and "other" approaches in 24% of the cases. Other approaches included switching to an atherectomy device, treating another area or choosing a smaller balloon. Patients originally undergoing DCA and found to require a change in therapeutic approach following ultrasound needed further passes with the atherectomy device in 17% of the cases, a different catheter orientation in 30% of the cases, a different sized device in 22% of the cases, and a switch to a balloon device in 35% of the cases. In 26% of the cases, ultrasound images convinced operators that a satisfactory endpoint was achieved. Out of the total 136 patients, five had spasms associated with ultrasound imaging requiring intracoronary nitroglycerin and observation. No other complications associated with ultrasound imaging were observed. Among conclusions noted by Mullen, who presented the study results, was that "the amount of plaque was commonly underestimated by angiography compared to ultrasound." Phase II of the study has already begun and is being performed with CVIS' Interpret 3.9 French imaging catheter as well as its 4.3 French catheter. Cleared in November 1991, the Interpret was developed by InterTherapy, a company which was acquired by CVIS in September 1992. The Phase II study is being conducted in a blinded fashion with the objective of identifying morphologic predictors of adverse outcomes. Another study, presented the same day of the conference by investigator Gary Mintz, MD, Washington Hospital Center, Washington, D.C., looked at the influence of pretreatment intravascular ultrasound imaging on transcatheter treatment strategies in 329 patients. The study, which used the Interpret 3.9 French catheter, found that "preintervention imaging can be performed routinely and safely in a multidevice environment with experienced operators" and that "preintervention imaging influences treatment decisions in approximately 40% of patients." Preintervention imaging was successful in 91.8% of lesions; reasons for failure included the inability to reach or cross the lesion and "poor image quality that precluded useful online measurement," according to Mintz. He concluded that in general "ultrasound measurement of lesion length, target lesion calcium and lesion eccentricity has a major impact on revascularization strategy selection."



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