JIC: Some stents may be prone to error, adverse outcomes
Balloon-expandable stents are meant to help reduce the rates of restenosis by preventing elastic recoiling post-PCI; however, a study published in the Nov. 17 issue of the Journal of Interventional Cardiology found that these types of stents may be poorly designed and actually could lead to adverse clinical outcomes.
Antwan D. Robinson, MD, an interventional cardiologist at Detroit Medical Center's Cardiovascular Institute, and colleagues presented a case study of a 65-year-old male with hypertension, hyperlipidemia, diabetes and cerebral vascular accident who had an ejection fraction of 65 percent. His right coronary artery was of a large caliber with calcified vessels that had moderate to severe stenosis. Robinson and colleagues decided to perform PCI with the Taxus Ion drug-eluting stent (Boston Scientific).
During the procedure, Robinson et al reported difficulty advancing the stent into the lesion due to tortuosity and calcification. “Upon further review of the films, the proximal and distal portions of the stent appeared to be deformed, accordioned and shortened,” the authors wrote.
Post-hospital discharge, the patient was readmitted with a sudden onset of chest pain; he had an acute inferior MI and was revascularized immediately. During the procedure, the researchers were unable to advance the wire through the proximal of the stent and the patient was instead managed medically.
“The original purpose of the coronary stent was to reduce restenosis by preventing elastic recoil after percutaneous coronary interventions,” the authors noted. “Thus, stents were engineered to have adequate radial strength and precise measurement was routinely reported by the manufacturer, allowing physicians to choose a stent based on radial strength criteria.”
The authors noted that early generation stents were more rigid and shortening was not observed. “Stent shortening resulting in geographic miss occurred occasionally after deployment of self-expanding stents; however, this was thought to be due to characteristics of nitinol material and the inherent difficulty in the stent moving during unsleeving of the device,” the authors wrote.
Robinson said that stent shortening was a topic at two of the latest interventional meetings and pointed out that stent shortening occurred in some patients who received both the Boston Scientific's Taxus Element and Omega stents. It was noted that there were 358 complaints regarding the Element stent platform filed between April 2009 and May 2011. Stent length change was reported in 14.9 percent, crimped stent damage in 8 percent and malapposition in 2.1 percent of the complaints.
“Upon personal experience handling the stent out of the body and observing its action in models, it became clear to the authors that there are differences in longitudinal strength between different stent designs,” they noted. “[W]e believe that the stent may have been incompletely deployed due to the calcification and tortuosity of the vessel. After deflation of the stent deployment balloon, we believe that the 'winged' balloon snagged the distal struts during withdrawal, resulting in distal accordion.
“This case and bench testing studies demonstrating reduced longitudinal strength should raise concerns regarding the use of the Element, Omega, or Ion stent platforms, particularly in tortuous vessels where the stent may be snagged by the balloon or other adjunctive devices,” Robinson et al concluded.
In an accompanying editorial, Cindy L. Grines, MD, vice president of academic and clinical affairs at Detroit Medical Center, called the fact that this family of stents may be more prone to stent shortening “disturbing,” and said that while this may be a simple case of placing an additional stent, in the case of Detroit Medical Center, the stent was shown to deform.
While Grines noted that the FDA and Boston Scientific are aware of the issue, she concluded that “until further data are available, our institution will use the Ion stent cautiously, and only when alternatives are unavailable for the size under consideration.”
Antwan D. Robinson, MD, an interventional cardiologist at Detroit Medical Center's Cardiovascular Institute, and colleagues presented a case study of a 65-year-old male with hypertension, hyperlipidemia, diabetes and cerebral vascular accident who had an ejection fraction of 65 percent. His right coronary artery was of a large caliber with calcified vessels that had moderate to severe stenosis. Robinson and colleagues decided to perform PCI with the Taxus Ion drug-eluting stent (Boston Scientific).
During the procedure, Robinson et al reported difficulty advancing the stent into the lesion due to tortuosity and calcification. “Upon further review of the films, the proximal and distal portions of the stent appeared to be deformed, accordioned and shortened,” the authors wrote.
Post-hospital discharge, the patient was readmitted with a sudden onset of chest pain; he had an acute inferior MI and was revascularized immediately. During the procedure, the researchers were unable to advance the wire through the proximal of the stent and the patient was instead managed medically.
“The original purpose of the coronary stent was to reduce restenosis by preventing elastic recoil after percutaneous coronary interventions,” the authors noted. “Thus, stents were engineered to have adequate radial strength and precise measurement was routinely reported by the manufacturer, allowing physicians to choose a stent based on radial strength criteria.”
The authors noted that early generation stents were more rigid and shortening was not observed. “Stent shortening resulting in geographic miss occurred occasionally after deployment of self-expanding stents; however, this was thought to be due to characteristics of nitinol material and the inherent difficulty in the stent moving during unsleeving of the device,” the authors wrote.
Robinson said that stent shortening was a topic at two of the latest interventional meetings and pointed out that stent shortening occurred in some patients who received both the Boston Scientific's Taxus Element and Omega stents. It was noted that there were 358 complaints regarding the Element stent platform filed between April 2009 and May 2011. Stent length change was reported in 14.9 percent, crimped stent damage in 8 percent and malapposition in 2.1 percent of the complaints.
“Upon personal experience handling the stent out of the body and observing its action in models, it became clear to the authors that there are differences in longitudinal strength between different stent designs,” they noted. “[W]e believe that the stent may have been incompletely deployed due to the calcification and tortuosity of the vessel. After deflation of the stent deployment balloon, we believe that the 'winged' balloon snagged the distal struts during withdrawal, resulting in distal accordion.
“This case and bench testing studies demonstrating reduced longitudinal strength should raise concerns regarding the use of the Element, Omega, or Ion stent platforms, particularly in tortuous vessels where the stent may be snagged by the balloon or other adjunctive devices,” Robinson et al concluded.
In an accompanying editorial, Cindy L. Grines, MD, vice president of academic and clinical affairs at Detroit Medical Center, called the fact that this family of stents may be more prone to stent shortening “disturbing,” and said that while this may be a simple case of placing an additional stent, in the case of Detroit Medical Center, the stent was shown to deform.
While Grines noted that the FDA and Boston Scientific are aware of the issue, she concluded that “until further data are available, our institution will use the Ion stent cautiously, and only when alternatives are unavailable for the size under consideration.”