The INFINITY-SWEDEHEART trial shows clinical benefit appearing at 6 months in ACS patients treated with the DynamX Bioadaptor versus Resolute Onyx—exactly when the bioadaptor's polymer coating resorbs and its helical strands unlock.
Device Comparison Between Permanent and Adaptive Structures
The DynamX bioadaptor features:
- 71 μm cobalt-chromium struts arranged in sinusoidal rings connected by three S-links
- Three uncaging elements per ring held together by 6 μm polymer coating
- Polymer resorption over six months, allowing helical strands to unlock while maintaining longitudinal continuity
- Sirolimus release over three months during polymer degradation
Resolute Onyx maintains permanent strut structure with durable polymer coating delivering zotarolimus. The bioadaptor's strands unlock at six months when polymer resorbs. Resolute Onyx maintains its permanent structure throughout.
Trial Population and Design
INFINITY-SWEDEHEART enrolled 2,400 patients with 25% STEMI and 37% NSTEMI, totaling 77% ACS presentation including unstable angina. The prespecified landmark analysis measured clinical events from 6 months onward—the timepoint when the bioadaptor's strands unlock.
Outcome Data Shows Divergence After Uncaging
Event curves diverge at 6 months when DynamX unlocks, showing 48% reduction in target lesion failure through 2 years with plateau in bioadaptor arm versus steady event accumulation with permanent DES.
At the 1-year landmark analysis (6 to 12 months post-procedure), target lesion failure occurred in 0.3% of bioadaptor patients versus 1.7% with Resolute Onyx—an 81% relative risk reduction (HR 0.19; 95% CI 0.06-0.65; p=0.0079). Target vessel failure showed comparable divergence: 0.8% versus 2.5% (HR 0.35; 95% CI 0.16-0.79; p=0.011).
Through 2 years, the pattern persisted:
| Timepoint | Endpoint | DynamX Bioadaptor | Resolute Onyx | Relative Risk Reduction | P-value |
|---|---|---|---|---|---|
| 6-12 months | TLF | 0.3% | 1.7% | 81% (HR 0.19) | 0.0079 |
| 6-12 months | TVF | 0.8% | 2.5% | 65% (HR 0.35) | 0.011 |
| 6-24 months | TLF (cumulative) | 1.47% | 2.81% | 48% (HR 0.52) | 0.027 |
| ACS subgroup (6-12 months) | TLF | 0.3% | 1.8% | 83% (HR 0.17) | 0.018 |
Investigators noted a plateau in target vessel MI and ischemia-driven target lesion revascularization in the bioadaptor arm, while the Resolute Onyx arm showed steady event accumulation. In the ACS subgroup specifically, benefit proved substantial—continuing through 2 years (p=0.0175).
Mechanism Linking Strut Thickness, Uncaging, and ACS Healing
Thin-strut designs induce less inflammation and less vessel injury compared to thicker struts. At 71 μm, the bioadaptor sits at the lower end of contemporary DES strut thickness.
After polymer resorption, the unlocked helical strands allow the vessel to move and function in response to hemodynamic needs, restoring adaptive remodeling and pulsatility. At 9- to 12-month imaging, investigators documented late vessel expansion measured by IVUS—compensating for neointimal increase that occurs with permanent DES.
The 12-month OCT assessment found 98% of bioadaptor struts covered with no malapposed struts and neointimal hyperplasia thickness of only 0.19 mm. No TLF events or definite device thrombosis occurred beyond 6 months.
Uncovered and malapposed struts occur more commonly following stenting in acute coronary syndromes than in stable lesions. DES implantation in inflamed environments results in delayed vessel wall healing that can persist up to 48 months. The bioadaptor's thin struts, complete polymer resorption, and vessel uncaging work in this specific context—ACS lesions where delayed healing and incomplete endothelialization pose ongoing risk.
Clinical Implications for Device Selection
For interventionalists treating ACS patients, INFINITY-SWEDEHEART demonstrates superiority in a population where over three-quarters had acute presentations. The bioadaptor showed 48% risk reduction in target lesion failure from 6 months through 2 years, with 83% relative risk reduction in the ACS subgroup during the first year after uncaging.
Consider the bioadaptor specifically in acute presentations where delayed healing and incomplete endothelialization pose ongoing risk—the population where the most substantial benefit was demonstrated. Event curves diverge at 6 months when the device unlocks and remain diverged through 2 years, with a plateau in the bioadaptor arm versus steady event accumulation with permanent DES.
The benefit appears when the device transforms, in vessels still healing from acute coronary syndrome.
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BIOADAPTOR-RCT 2-year outcomes: The per-protocol analysis showed TLF rates of 1.8% versus 5.5% in stable coronary disease patients, with risk difference of -3.6% favoring the bioadaptor.
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Three-year divergence continues: TLF curves diverged further after 1-year follow-up with significant differences in both TLF and cardiac death rates favoring DynamX over permanent DES.
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Strut thickness and thrombogenicity: Thick-strut stents at 162 μm were 1.5-fold more thrombogenic than 81 μm struts in porcine coronary arteries, presenting 60% more thrombus formation at 3 days.
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Adaptive remodeling on imaging: IVUS measurements documented late vessel expansion that compensated for neointimal increase, unlike permanent DES where lumen decreases over time.