SCAI.15 From Atherectomies to Antiplatelets

The Society for Cardiovascular Angiography and Interventions (SCAI) held its annual meeting May 6-9 in San Diego. Here are some highlights from the late-breaking clinical trials.

Orbital atherectomy sustains benefits at two years

An atherectomy device that “sands” calcified lesions in coronary arteries before stenting proved to be effective and durable at two years, and possibly even cost-effective. Jeffrey Chambers, MD, presented the two-year results of ORBIT II (Orbital Atherectomy Treatment of Severely Calcified Coronary Lesions), which assessed the safety and efficacy of the Diamondback 360 Orbital Atherectomy System (Cardiovascular Systems) to prepare severely calcified coronary lesions for stent placement.

“This is the first trial that looks at long-term benefit, and with drug-eluting stents our revascularization rates are very low compared to other lesions with severe calcium,” says Chambers, who is director of the Cardiac Catheterization Laboratory at Mercy Hospital in Minneapolis.

The trial enrolled 443 patients at 49 sites in the U.S. who had severe calcification in the target lesion of at least 15 mm in length. At one year, the cardiac death rate was 3 percent, the target vessel revascularization/target lesion revascularization rate was 5.9 percent and the major adverse cardiovascular event rate was 16.4 percent. That increased to 4.3 percent, 8.1 percent and 19.4 percent, respectively, at two years.

“We don’t have a large body of knowledge to look at patients with severely calcified lesions,” Chambers acknowledges. He cited another trial that reported a one-year MACE rate of 19.9 percent. “Our MACE rate at two years is less than their one-year MACE rate.”

In an economic analysis, they found in an average-case scenario a cost savings of about $4,000, which offset the $3,795 price tag for the device. The best-case scenario produced a cost savings of $1,118 at one year. They determined that the Orbital approach cost $11,895 per life-year gained, which put it within the accepted threshold for value. 

Chambers proposes that this technique may be more successful than previous atherectomy devices because it orbits as well as rotates. “It treats a larger portion of the artery,” he says. “I believe it does something to break up the sheets of calcium and that potentially allows larger stent expansion. Stent expansion is really what translates to good long-term results.”

The FDA approved the Diamondback atherectomy device in coronary arteries in 2013. The ORBIT II trial was funded by Cardiovascular Systems.

In practice, prasugrel use may not mimic trials 

Cardiologists in real-world practice may not be optimizing the benefit of prasugrel in patients undergoing PCI, but they also don’t appear to be putting them in harm’s way.

“The therapeutic benefit is more modest in terms of reducing [thrombotic risk] compared to what we have seen in randomized data,” says Usman Baber, MD, MS, of Mount Sinai Hospital in New York. “However, simultaneously we see no significant increased risk of bleeding when used in this manner.”

Baber presented findings from PROMETHEUS, a registry-based study that compared the use of prasugrel (Effient, Daiichi Sankyo) and clopidogrel (Plavix, Bristol-Myers Squibb/Sanofi-Aventis) in patients with acute coronary syndrome (ACS) who received PCI at eight academic centers in the U.S. from 2010 and 2013. The FDA approved prasugrel as an antiplatelet agent in 2009 to treat ACS patients undergoing PCI. The agency based its decision on randomized trials that evaluated the safety and efficacy of prasugrel compared with clopidogrel (Plavix) in reducing ischemic events.

Prasugrel reduced the risk of thrombotic events but increased the risk of bleeding. PROMETHEUS was designed to clarify how these drugs were being used in clinical practice.

The PROMETHEUS researchers provided data on almost 20,000 patients. Of those, 20 percent received prasugrel and the rest clopidogrel. Compared with the clopidogrel group, prasugrel patients as a whole were younger, more likely to be male and less likely to have diabetes, hypertension, dyslipidemia, previous cerebrovascular disease, chronic kidney disease or anemia. They also were more likely to present with STEMI and non-STEMI.    

In unadjusted analyses, the 90-day rate of major adverse cardiovascular events—a composite of all-cause mortality, unplanned revascularization, stroke or MI—was 5.7 percent with prasugrel vs. 9.6 percent with clopidogrel. But after adjustments, the 42 percent relative reduction with prasugrel was reduced to 11 percent.

“For bleeding, we also found that prasugrel was paradoxically associated with a reduction in bleeding in unadjusted analyses,” Baber says. “But again, with the baseline differences, we found no statistical differences in bleeding rates between the two groups.”