As the most common type of heart disease and a leading cause of death in the US, coronary artery disease treatment is of significant importance. A recent study compares whether bioresorbable vascular scaffolds (BVS) are as safe and effective as drug-eluting stents (DES) for treating coronary artery disease.
Comparing Treatments for Coronary Artery Disease
Bioresorbable vascular scaffolds (BVS)are an emerging device for coronary artery disease treatment. They are biodegradable, naturally occurring and synthetic polymers designed to provide temporary mechanical support to vascular injuries (injuries obtained to the blood vessels such as arteries). Within several years, normal vascular function can be restored with complete resorption of the BVS, potentially improving longer-term outcomes.
Drug-eluting stents (DES), on the other hand, are small devices placed inside the arteries that slowly release a drug to help keep the coronary arteries open and blood flowing. However, limitations of DES including strut fractures (which can lead to restenosis, or narrowing of the blood vessels) and abnormal vasomotion (spontaneous oscillation of the blood vessel walls).
Previous clinical trial data has shown that there was no significant difference in most clinical outcomes between BVS and DES after one year. BVS did, however, show an increase in target vessel-related heart attack, which could be the result of an increase in device thrombosis (formation of a blood clot).
A recent systemic review by Ali and colleagues published in The Lancet analyzed seven randomised trials comparing the use of BVS and DES within two years after implementation and between one and two years. The seven trials included 5583 patients, who were randomly assigned BVS (3261 patients) or DES (2322 patients) and followed up for at least two years. The primary efficacy endpoint included cardiac mortality or target vessel-related heart attack, and the primary safety outcome was probable or definite device thrombosis.
The results showed that after the two year period, BVS was associated with an increased rate of target vessel-related heart attack thereby increasing the rate of device-oriented endpoints compared to DES. Furthermore, consistent with the earlier results, the rate of device thrombosis with BVS also increased.
Study Limitations
The clinical trials included in the analysis noted a number of limitations. Firstly, there were some sub-groups who actually fared better with BVS, including those with diabetes. Further research would be needed to investigate that relationship. Additionally, many high-risk patients were excluded from these trials, which limits the effectiveness of the results. Also, for many investigators, this was their first time using BVS, which means the importance of technique for optimal BVS use has not yet been established.
DES: A Superior Treatment for Coronary Artery Disease
In conclusion, the review provides evidence that DES is a superior coronary artery disease treatment compared to BVS with respect to both efficacy and safety over a two-year period. Long-term follow-up for these trials and other large-scale trials are necessary, however, to determine whether the risks associated with BVS use continue to increase beyond the two-year point or if benefits emerge after complete BVS bioresorption and vascular restoration occurs.
Written by Lacey Hizartzidis, PhD
Reference: Ali ZA, Serruys PW, Kimura T, Gao R, Ellis SG, Kereiakes DJ, Onuma Y, SimontonC, Zhang Z, Stone GW. 2-year outcomes with the Absorb bioresorbable scaffold for treatment of coronary artery disease: a systematic review and meta-analysis of seven randomised trials with an individual patient data substudy. Lancet. 2017Jul 18. pii: S0140-6736(17)31470-8.
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