COMFORTABLE-AMI: Biodegradable-Polymer DES Offers Lasting Benefit to STEMI Patients

PARIS, France—Compared with bare-metal stents (BMS), a biolimus-A9-eluting stent (BES) featuring a biodegradable polymer offers sustained protection from adverse events to patients with ST-segment elevation myocardial infarction (STEMI). Moreover, late-breaking results released Wednesday, May 22, at EuroPCR 2013, demonstrate that the benefits continue to accrue after 1 year, even after dual antiplatelet therapy is discontinued.

Lorenz Räber, MD, of Bern University Hospital (Bern, Switzerland), presented 2-year clinical and imaging data from the COMFORTABLE AMI (Comparison of Biolimus Eluted From an Erodible Stent Coating With Bare Metal Stents in Acute ST-Elevation Myocardial Infarction) trial. For the study, researchers randomized 1,161 STEMI patients to the BioMatrix BES (n = 575; Biosensors, Singapore) or the Gazelle BMS (n = 582; Biosensors).

One-year results, published in the Journal of the American Medical Association in August 2012, favored BES for the primary endpoint of MACE (composite of cardiac death, target vessel-related reinfarction, and ischemia-driven TLR).

What Happens After Halting Antiplatelets?

“In this study, we sought to investigate whether differences [between the 2 devices] are sustained throughout 2 years after discontinuation of dual antiplatelet therapy at 1 year,” Dr. Räber explained, noting that by protocol, such therapy was required up to 1 year. While more than 94% of patients were on aspirin therapy at 2 years, about 18% of patients were still on a thienopyridine.

Two-year follow-up, available in approximately 96% of the original cohort, again showed an advantage for BES compared with BMS in terms of MACE. The difference was driven by both target-vessel MI and clinically indicated TLR. Definite stent thrombosis was numerically lower for BES, though the difference was not significant (table 1).

Table 1. Cumulative Outcomes at 2 Years


(n = 556)

(n = 558)

HR (95% CI)

P Value




0.48 (0.31-0.72)


Cardiac Death



0.69 (0.37-1.27)


Target-Vessel MI



0.37 (0.15-0.87)


Clinically Driven TLR



0.36 (0.21-0.63)


Definite Stent Thrombosis



0.52 (0.23-1.26)


Landmark analysis performed at 1 year showed that the benefit in terms of MACE for BES “continues to accrue” up to 2 years, Dr. Räber said, “and was of similar effect size” in both periods.

BES were associated with a reduction in MI only in the first year (P = 0.03 for interaction). The largest effect on TLR was seen in the first year, though event curves continued to diverge through the second year. Stent thrombosis, meanwhile, was equivalent between BES and BMS in the second year, after most patients had stopped dual antiplatelet therapy (P = 0.25 for interaction; table 2).

Table 2. Landmark Analysis: BES vs. BMS


HR (95% CI)

P Value

Year 1
Year 2

0.49 (0.30-0.80)
0.45 (0.20-1.00)


Cardiac Death
Year 1
Year 2

0.81 (0.42-1.56)
0.20 (0.02-1.71)


Target-Vessel MI
Year 1
Year 2

0.20 (0.06-0.69)
0.98 (0.25-3.92)


Clinically Driven TLR
Year 1
Year 2

0.28 (0.13-0.59)
0.55 (0.23-1.30)


Definite Stent Thrombosis
Year 1
Year 2

0.42 (0.15-1.19)
1.48 (0.25-8.83)



Imaging substudies were performed, with 80 patients undergoing OCT and 81 undergoing IVUS at 13-month follow-up. Baseline characteristics were similar between the 2 treatment arms in each substudy.

While stent area and lumen area did not differ between BES and BMS immediately after treatment, lumen area was greater in BES- vs. BMS-treated vessels at 13 months (8.6 mm2 vs. 6.0  mm2; P < 0.001). The difference arose from “a substantial decrease in the bare-metal stent group due to neointimal hyperplasia,” Dr. Räber noted. Neointimal thickness of covered struts (primary endpoint) was 70 µm with BES and 270 µm with BMS (P < 0.001).

Uncovered struts were seen in 2.1% of BES patients and 0.1% of BMS patients at 13 months (P < 0.001). Strut malapposition occurred with similar frequency in both groups at baseline, while there was a trend toward slightly more persistent/acquired malapposed struts with BES (0.08% vs. 0.02% with BMS; P = 0.08).

Atherothrombotic material, defined as any tissue within the stent area, was less common shortly after BES vs. BMS treatment.

The lack of neointimal hyperplasia within BES-treated lesions explains the reduction in TLR at follow-up, Dr. Räber said. In addition, he pointed out, “the rates of very late stent thrombosis were similar, despite a higher rate of uncovered stent struts with BES and discontinuation of dual antiplatelet therapy at 1 year.”


Räber L. Biolimus-eluting stents with biodegradable polymer versus bare-metal stents in acute myocardial infarction: Two-year clinical follow-up and results of serial multimodality imaging (OCT/IVUS). The COMFORTABLE-AMI – IBIS-4 trial. Presented at: EuroPCR. May 22, 2013. Paris, France.



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  • The study was supported by grants from Biosensors, St. Jude Medical, the Swiss National Science Foundation, and Volcano.
  • Dr. Räber reports receiving institutional grant/research support from the Swiss National Science Foundation.