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Leaders of the embattled EXCEL study comparing percutaneous intervention (PCI) with coronary artery bypass grafts (CABG) vowed complete transparency as they sought to refute accusations that they withheld key data and misrepresented others.

"On behalf of the EXCEL leadership, we hereby respond to the misleading narrative questioning the conduct of the EXCEL trial that has been reported by certain members of the cardiovascular surgical community and a recent BBC Newsnight program," according to a by principal investigator Gregg Stone, MD, of Icahn School of Medicine at Mount Sinai in New York City, and 10 other EXCEL investigators.

Earlier this week, the British news outlet accused EXCEL leaders of burying data unfavorable to PCI, a revelation that resulted in the European Association for Cardiothoracic Surgery (EACTS) withdrawing its support for guideline recommendations on left main revascularization that depended heavily on EXCEL.

Now, the EXCEL trialists say that EACTS acted "without so much as even asking the EXCEL study group for clarification."

The crux of the issue was that procedural MI according to the Third Universal Definition, though it had been listed in the protocol as an exploratory secondary endpoint, was never reported publicly. "Newsnight has seen that unpublished data and it shows that under the universal definition, patients in the trial that had received stents had 80% more heart attacks than those who had open heart surgery," .

Stone's team responded that the Universal Definitions requires troponin measurements, which were optional in EXCEL and infrequently performed by centers because of cost. "Thus, reporting procedural MI rates according to Universal Definition was not possible," according to the authors.

"We have published >30 manuscripts to date from EXCEL, and plan on 100 or more papers before we're finished. Our goal is to be completely transparent with all the data from this landmark study," they wrote, promising two future manuscripts on the rates and implications of MI according to various definitions, including the Universal Definition using creatine kinase-myocardial banding.

As for why they had not used the Universal Definition of MI for the primary endpoint in the first place, Stone and colleagues explained that it was not suitable because of ascertainment bias, different criteria for PCI and CABG, and lack of demonstrated correlation with prognosis. They said the whole research team agreed unanimously -- surgical colleagues included -- on this point at the study's outset.

Rebuttals to other claims of trial misconduct -- that the definition of MI had changed over the course of the study, for example -- were hashed out in the rest of the statement.

EXCEL was first presented at the Transcatheter Cardiovascular Therapeutics meeting in 2016 with an accompanying paper in the .

Three-year data from the trial showed noninferiority for PCI in comparison with CABG in lower surgical risk patients with left main coronary artery disease, whereas the (presented at the same meeting) showed CABG to be superior to PCI.

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