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For other articles and previous issues click here. April 24, 2006
In the Game Presentations at the American College of Cardiology show that cardiologists definitely want in on the high-stakes game of CT angiography, just like they did in interventions. Three featured presentations at the annual meeting of the American College of Cardiology (ACC) in Atlanta last month dispelled any doubt that cardiologists are not paying close attention to coronary CT angiography (CTA). Some of the first clinical data from an experimental 256-slice CT scanner was presented at the meeting. Also of interest to the radiology community was news on both cardiac and carotid artery stenting. One
Beat “The 2nd Spec 256-Multislice CT seems to be a promising next-generation CT for coronary and cardiac imaging,” said Akira Kurata, MD, PhD, in a release announcing the initial results. Kurata is the lead author of the study reporting early clinical results of the 256-slice system. “We are pleased by the speed of the procedure, which allows us to assess patients with just one beat of the heart.” The system completes the whole heart scan in 1.5 seconds without gating and table movement because of the wider coverage of the CT scanner. That compares with a 10-second image acquisition time, according to information provided by Kurata and colleagues at the meeting. Kurata and researchers at Japan’s Ehime University School of Medicine reported results from two patients who previously had heart attacks. The investigators found that they could clearly and effectively evaluate the damage from the patients’ previous heart attacks. Using contrast solution, the researchers were able to evaluate coronary artery structure and the function of the left ventricle, which is the main pumping chamber of the heart. Researchers were also able to evaluate the volume of blood moved during the heart’s filling and emptying cycles and the heart’s pumping capacity. CTA
in the Emergency Department CTA patients were discharged sooner than the standard of care group—a median 6.2 hours compared with 14.1 hours. The total cost for the patients in the CTA was $300 less than incurred when the standard evaluation was used. “Our study shows that CTA can rapidly and definitively exclude CAD as the cause for acute chest pain,” said William Beaumont Hospital Medical Director Gilbert L. Raff, MD, FACC, via a release. “Immediate use of CTA helps reduce a patient’s length of hospital stay and decreases overall cost without putting the patient at increased risk.” In yet another CTA study, researchers looked at using CTA as a diagnostic tool after a patient has a “mildly abnormal” or “equivocal” nuclear perfusion scans. Jason H. Cole, MD, MSc, and colleagues at Cardiology Associates of Mobile, Ala., looked at a series of 206 consecutive patients who underwent CTA after unclear diagnoses after perfusion tests. By using CTA before, the researchers found no evidence of CAD in 29.6%, eliminating the catheterization in those cases. By not going straight to catheterization in those cases, the average cost per case dropped from $4,075 per case with immediate catheterization to $1,809 among the study group with CTA between perfusion and catheterization. The savings was $2,266 per patient (55.6%). “In clinical practice, a strategy that uses coronary CT angiography as a gatekeeper to catheterization is cost saving as opposed to initial catheterization for patients with equivocal or mildly abnormal nuclear perfusion scans,” the authors wrote in the conclusion of their study abstract. Stenting
Studies Data from patients treated with carotid stenting since its FDA approval revealed no unexpected problems. The results from an ongoing clinical registry show a lower combined rated of death, stroke, and heart attack within 30 days of stenting than reported in the clinical trials that led to the device’s FDA premarket approval. “The transfer of carotid stenting technology from clinical trial sites to clinical practice sites appears to have been successful with the same, or even better outcomes in the clinical setting,” said William A. Gray, MD, in a release announcing the presentation in Atlanta. Gray is an associate professor of medicine and director of the endovascular services at NewYork-Presbyterian Hospital/Columbia University Medical Center in New York. Gray reported registry data on more 2,500 of 3,000 patients treated by 240 interventionalists at 118 medical centers in the United States. The study requirement was mandated by the FDA when it approved the carotid stent manufactured by Guidant Corporation. The study, dubbed the CAPTURE Trial, was designed to determine whether carotid artery stenting can be performed safely in real-world clinical settings with physicians of varying levels of experience and to evaluate Guidant’s training program for the stent. According to Guidant, the primary endpoint of 30-day death, stroke, and myocardial infarction (MI) is 5.7% in the study of high-risk patients. The rate of those events leading to significant disability or death (30-day major stroke and death) is 2.5%. “The large enrollment and excellent results of CAPTURE show that carotid artery stenting has truly arrived as the treatment for high-surgical risk patients with carotid artery disease at risk of stroke,” Gray said in a press release announcing the results. “This landmark U.S. trial is the largest and most rigorous real-world study of carotid stenting with independent neurologic follow up and stroke event adjudication. The results demonstrate that with proper experience levels and device training, carotid stenting can be performed with exemplary results by a variety of physicians in community hospital settings.” Absorbable
Cardiac Stents German researchers presented the initial results of a magnesium stent that is absorbed by the body in first few months after it is placed in the artery. Initial results from the first 63 patients to receive the stent were reported at the Atlanta meeting. The human body requires magnesium, so the degrading stent material is absorbed and used in the body. The BIOTRONIK Absorbable Metal Stents (AMS) demonstrated the safety and feasibility of the technology. At four months’ follow-up, researchers reported no cardiac deaths, no nonfatal MIs, and no cases of stent thrombosis, and minimal neointimal growth, according to the company. Larger trials are needed to evaluate the stent’s efficacy in coronary arteries, BIOTRONIK representatives pointed out. The researchers also used ultrasound to confirm that the stent had completely degraded, which means the AMS would be completely MRI compatible, which would provide physicians the opportunity for noninvasive follow-ups throughout the course of treatment to their patients. According a report on the meeting published in the Milwaukee Sentinel, an absorbable stent that would disappear in a few months would offer several other potential benefits: • dangerous blood clots can form inside stents; • CT scans become cloudy from the metal in the stent; and • the magnetic field and a MRI can affect a metal stent. The stent still needs to overcome a substantial obstacle. According to BIOTRONIK, the trial revealed a restenosis rate that is higher than is associated with current stents. The developers hope to modify the stent technology to bring that rate in line with current clinical standards. “The AMS is not just another stent. It represents a revolutionary leap forward in vascular intervention treatment. The AMS provides the necessary short-term scaffolding needed to support the vessel during the healing process and is then absorbed, avoiding the long-term mechanical stress of current permanent stent technologies,” said Professor Raimund Erbel, MD, FACC, FESC, principal investigator of the trial, in a release announcing the results. “…By fine-tuning the AMS degradation rate to optimize mechanical performance over time, the AMS should achieve coronary results similar to the very positive results the system achieved in earlier animal and human peripheral studies. Eventually, this will lead to an entire new field of absorbable treatments that will establish a new standard in patient care.” —
A Radiology Today staff report compiled from the American College
of Cardiology and various other sources
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