The bigger issue
Importantly, the recent AHA/ACC/SCAI coronary revascularization guidelines used ISCHEMIA data to support downgrading the CABG recommendation from class 1 to class 2B in 3-vessel CAD with normal left ventricular function and from class 1 to 2a in 3-vessel CAD with mild to moderate left ventricular dysfunction.
The trial reported no significant benefit with an initial invasive strategy over medical therapy in stable patients with moderate or severe CAD. European guidelines, however, give CABG a class I recommendation for severe three- or two-vessel disease with proximal left anterior descending (LAD) involvement.
Dr. Sabik and Dr. Bakaeen say patients with severe three- or two-vessel disease with proximal LAD involvement were underrepresented in the randomized trials cited by the guidelines but are the typical CABG patients in modern-day practice.
“That is why it is important to determine the severity of CAD accurately and definitively in ISCHEMIA,” Dr. Bakaeen said. “But the more we look at the data, the more errors we encounter.”
Two U.S. surgical groups that were part of the writing process withdrew support for the revascularization guidelines, as did several international surgical societies, citing the data used to support the changes as well as the makeup of the writing committee.
Dr. Ferguson, now with the medical device manufacturer Perfusio, said he resigned from the ISCHEMIA steering committee on May 8 after being unable to accurately reconcile the ISCHEMIA surgical subset data with the Reynolds substudy and two other ISCHEMIA papers on the CABG subset. At least one of those papers, he noted, was being hurriedly pushed through the review process to counter concerns raised by surgeons regarding interpretation of ISCHEMIA.
“This is the first time in my lengthy career in medicine where a level of political agendaism was actually driving the truck,” he said. “It was appalling to me, and I would have said that if I was an interventional cardiologist looking at the results.”
ISCHEMIA results have also been touted as representing state-of-the-art care around the world, but that didn’t appear to be the case for the surgical subset where, for example, China and India performed most CABGs off pump, and globally there was considerable variation in how surgeons approached surgical revascularization strategies, Dr. Ferguson said. “Whether this variability might impact the guideline discussion and these papers coming out remains to be determined.”
He noted that the study protocol allowed for the ISCHEMIA investigators to evaluate whether the variability in the surgical subset influenced the results by comparing the data to that in the Society of Thoracic Surgeons registry, but this option was never acted upon despite being brought to their attention.
“Something political between 2020 and 2022 has crept into the ISCHEMIA trial mindset gestalt, and I don’t like it,” Dr. Ferguson said. “And this can have enormous consequences.”
Asked whether their letters to Circulation are being used to undermine confidence in the ISCHEMIA findings, Dr. Sabik replied, “It is not about undermining ISCHEMIA, but understanding how applicable ISCHEMIA is to patients having CABG today. Understanding the severity of the CAD in patients enrolled in ISCHEMIA is, therefore, necessary.”
“The authors and Circulation have admitted to errors,” he said. “We want to be sure we understand how severe the errors are.”
“This is just about accuracy in a manuscript that may affect patient treatment and therefore patient lives. We want to make sure it is correct,” Dr. Sabik added.
A version of this article first appeared on Medscape.com.