Statistical error reverses noninferiority finding in head-to-head trial of DES, bioresorbable scaffold

In a reversal, investigators for a trial comparing Biotronik‘s bioresorbable, drug-eluting Orsiro stent and Biosensors‘ BioFreedom drug-eluting stent reported this week that Biosensors’ device did not meet the criteria for noninferiority.

The researchers said that while preparing the study for publication in a journal, they discovered a statistical error that ultimately changed the trial’s conclusion. The results were first presented earlier this year at the 2018 Transcatheter Cardiovascular Therapeutics meeting.

“We had initially said the BioFreedom stent was not worse than the Orsiro stent,” co-principal investigator Dr. Lisette Okkels Jensen said in prepared remarks. “Now, when we found a non-significant P-value, the overall message is that it didn’t meet the criteria for non-inferiority.”

The all-comers trial included 3,151 people with chronic stable coronary artery disease. The study’s primary endpoint included cardiac death, myocardial infarction related to the index lesion and target lesion vascularization at one year. The composite endpoint was met in 5.2% of people treated with the BioFreedom device and 4% of the Orsiro group.

Cardiac deaths were reported in 1.2% of the people in the BioFreedom group and 2.1% of those treated with Orsiro – these data were not statistically significant. After one year, the rates of myocardial infarction were similar between the two groups. The rates of definite stent thrombosis and definite/probable stent thrombosis were also similar. There were more target lesion revascularizations needed in the group treated with the BioFreedom device.

Biosensors’ chief medical officer Dr. Hans-Peter Stoll reportedly pointed out that the BioFreedom stent is specifically designed for patients at high risk for bleeding for whom dual antiplatelet therapy after one month would not ideal.

In another trial reported at this year’s TCT meeting, the BioFreedom stent performed better than a bare metal stent in a population of patients who were at a high risk of bleeding.

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