The polymers used in stents are non-biodegradable, and they have stainless steel components, both of which are linked to increased risk of complications.
Coronary artery stents are metal scaffolds designed to unblock the arteries that supply blood to the heart. Stents inserted in patients over the past decade have typically been drug-eluting, which means they are coated with medication to prevent the artery from becoming blocked again.
However, the polymers used in these stents are non-biodegradable, and they have stainless steel components, both of which are linked to increased risk of complications.
The advantages the new stent has over these earlier drug-eluting stents are that the strut used in the stent is not thick stainless steel, but is "ultrathin" cobalt-chromium - the thinnest strut that is currently available - and that the polymer used is biodegradable.
To test the effectiveness of the new stent, patients with coronary artery disease were randomly assigned to either receive the new stent or the standard type of stent. In total, 1,063 people received the new, experimental stent, while 1,056 received the standard stent.
The researchers followed the patients for 12 months after they received the stents. The study found that similar numbers of patients in both groups either died from heart problems, had a heart attack caused by the artery becoming blocked again or required another operation on the same artery within the study period.
Within the experimental stent group, these adverse effects happened to about 6.5% of the participants, while in the normal stent group they happened to about 6.6% of the participants.
Benefits were most apparent in subgroup, but more research is needed
In a subgroup of patients who had heart attacks, the new stent exhibited a much clearer lead over the normal stent. In this subgroup, 3.3% of the participants fitted with the experimental stent experienced the adverse effects, compared with 8.7% of participants who were fitted with the normal stent.
According to study author Dr. Thomas Pilgrim, from the Swiss Cardiovascular Center at University Hospital in Bern, Switzerland, the new stent "matched the outcomes of one of the safest and most effective new generation drug-eluting stents" and "represents the next logical step in stent refinement by combining an ultrathin platform with a polymer that completely degrades."
However, on the subject of the differences in the heart attack subgroup, Dr. Pilgrim admits that the team "cannot exclude that these findings are due to chance alone." He says that future studies will need to explore whether these differences can be reproduced in this subgroup.
In 2012, Medical News Today reported that Medtronic Inc's Resolute Integrity™ Drug-Eluting Stent had been approved by the Food and Drug Administration. The manufacturer claimed that this stent improved on its previous bare metal stent, by incorporating what the company terms "continuous sinusoid technology."
Continuous sinusoid technology involves "one continuous, single strand of wire that is molded into a sinusoidal wave and then wrapped in a helical pattern and laser-fused at certain points, making each stent comparable to a flexible spring."
Also in 2012, a study found that stent-implant patients were one-and-a-half times more likely to die if they were depressed, compared with stent-implant patients who were not depressed.
The researchers behind that study commented that physicians traditionally focus on medical factors - such as diabetes or family history of heart disease - when assessing stent-implant patients' risk of death, "but that's not the whole picture. Psychological factors do matter as well, in combination with the medical factors."