OCT-ORION: Durable polymer ZES shows better healing, strut coverage vs. bioabsorbable DES

A zotarolimus-eluting stent with a durable polymer had better healing metrics vs. a bioabsorbable polymer drug-eluting stent at 9 months, according to findings presented at EuroPCR.

OCT results indicated the second-generation zotarolimus-eluting stent (ZES; Resolute Integrity, Medtronic) had better strut coverage at 2 to 6 months and 9 months than the second-generation bioabsorbable polymer DES (BioMatrix NeoFlex, Biosensors International), according to Stephen W.L. Lee, MD, of Queen Mary Hospital, University of Hong Kong, and colleagues.

Stephen W.L. Lee

The researchers designed a protocol to identify the differences between stent platforms using a much smaller sample size than would otherwise be necessary. All patients (n = 60) received both stents in the same index procedure and underwent longitudinal sequential OCT assessments. At 2 to 6 months, researchers quantified stent strut coverage, and at 9 months, they assessed neointimal progression and maturation, as well as OCT metrics. The primary endpoint was difference in OCT percentage strut coverage at 9 months.

Lee and colleagues hypothesized that the DES with bioabsorbable polymer would show better healing and strut coverage at 2 to 6 months, but that the ZES with durable polymer would show better neointimal suppression at 9 months.

“There are two important messages from this study,” Lee said in an interview with Cardiology Today’s Intervention. “One is that the conventional wisdom of thinking that the DES with a biodegradable polymer is better than that with a durable polymer is probably untrue. The second is that we might have a very good novel protocol for future studies comparing stent platforms.”

All patients were evaluated at baseline; then randomly assigned to one of five early OCT assessment groups: at 2 months, 3 months, 4 months, 5 months or 6 months; and then had a final OCT follow-up at 9 months.

Contrary to the postulations, the ZES had higher strut coverage than the bioabsorbable polymer DES at 2 to 6 months, statistically significant at 3 (95.4% vs. 86.6%; P = .004) and 6 months (99.7% vs. 98.2%; P = .002), with the largest absolute differences occurring in the earlier months, according to the researchers.

Early strut coverage also was better for the ZES in the subset of patients with diabetes (median, 97.5% vs. 95.5%; P = .0016).

At 9 months, the ZES had better strut coverage (99.7%; interquartile range, 99.1-100) compared with the bioabsorbable DES (99.6%; interquartile range, 96.8-99.9; P = .0009), Lee and colleagues found.

Neointimal suppression at 9 months was similar in both stents. According to the results, there were no significant differences in percent diameter stenosis (difference, 0.29; 95% CI, –4.88 to 4.74) and number of vessels with angiographic binary restenosis (difference, –1.7%; 95% CI, –10.5 to 7.2).

No cases of MI or stent thrombosis were observed, and one patient in both the ZES and bioabsorbable polymer DES arms required revascularization at 9 months.

Newest-generation durable polymers “are good enough in many ways that we don’t really need the so-called biodegradable polymers,” Lee told Cardiology Today’s Intervention. “There is no need to rush for biodegradable polymers if we have a very good [durable] polymer like the one used in the current study.”

Experience with longitudinal sequential OCT assessments has taught that “if you see very good healing at the very beginning, it will translate into excellent healing with future benefits in outcomes,” Lee said. “We can use this protocol to predict better outcomes while waiting for the clinical correlations in the next 5 years.” Widespread adoption of the protocol could save on research costs in the future, he said. – by Erik Swain

Reference:

Lee SW, et al. Late-Breaking Trials and Trial Updates in Coronary Interventions. Presented at: EuroPCR; May 16-19, 2016; Paris.

Disclosure: The study devices were provided for free by Biosensors International and Medtronic. Lee reports no relevant financial disclosures.