Conference Coverage

Noncardiac mortality is not increased by revascularization in a meta-analysis: New data refute recent study



In response to a randomized trial that associated elective revascularization for ischemia with an increase in noncardiac mortality versus medical therapy alone, a meta-analysis with a far larger dataset challenges this assertion, suggesting the initial conclusion is due to a type 1 error.

With data from nearly 17,000 patients in 18 randomized trials, the meta-analysis showed no signal for increased noncardiac mortality in the revascularization group overall or across several sensitivity analyses, reports William Wijns, MD, PhD, professor of interventional cardiology, National University of Ireland, Galway.

The larger pool of data from the meta-analysis was considered compelling by several experts at the annual meeting of the European Association of Percutaneous Cardiovascular Interventions, where it was presented.

“I think these data will close once and forever this controversy,” said Davide Capodanno, MD, PhD, a professor of cardiology and interventional cardiologist at the University of Catania (Italy).

Evidence for an unexpected increased risk of noncardiac mortality was drawn from the ISCHEMIA-EXTEND study, which was published earlier this year. Numerous prior studies comparing percutaneous intervention (PCI) to medical therapy for relief of ischemia had shown no such safety signal.

The ISCHEMIA-EXTEND study provided long-term follow up of patients enrolled in ISCHEMIA, a study that randomized patients with stable coronary disease and moderate or severe ischemia to PCI or a conservative approach. After 3.2 years of follow up, there was no reduction in risk of cardiovascular events or all-cause death. While this lack of benefit was a disappointing result from the perspective of interventional cardiology, there was also no increase in these risks.

In ISCHEMIA-EXTEND, the more than 5,000 patients originally randomized were followed for an additional 2.5 years (total 5.7 years). During this extended period, the estimated 7-year risk of cardiovascular mortality was 22% lower in the group randomized to PCI (hazard ratio, 0.78; 95% confidence interval, 0.63-0.96) but the noncardiac mortality was increased by 44% (HR, 1.44; 95% CI, 1.08-1.91). Because of the counterbalancing effects on survival, all-cause mortality was similar in the two groups.

The newly completed meta-analysis was undertaken to address this surprising result not least because the increased rates of noncardiac death did not have a plausible explanation, according to Dr. Wijns.

When the patients from the 18 randomized trials were compared, noncardiac death occurred in 4.68% of the 8,665 patients assigned to elective revascularization and in 4.17% of the 8,243 patients assigned to medical therapy alone at an average follow up of 5.7 years.

This difference was not significant overall (HR, 1.09; 95% CI, 0.94-1.26; P = .26) or after sensitivity analyses. For example, there was no difference (P = .52) between an invasive or conservative approach after controlling for length of follow up.

There was also no heterogeneity (I2 = 0%) among the studies when ISCHEMIA-EXTEND was excluded.

Absence of negative effect ‘is confirmed’

On the basis of a Bayesian meta-analysis designed to account for residual uncertainty (relative risk, 1.08, 95% CI, 0.90-1.30) and the consistency of results among all studies with the exception of ISCHEMIA-EXTEND (RR, 1.0; 95% CI, 0.84-1;18; P = .7), “the absence of a negative effect of revascularization on noncardiac death was confirmed,” Dr. Wijns reported.

Based on the preponderance of evidence assembled in this meta-analysis, the “noncardiac mortality excess risk observed following revascularization relative to medical therapy was confined to a single large trial and is likely due to a type 1 error,” Dr. Wijns reported. He noted that this study is “the first large-scale meta-analysis study designed to systematically evaluate potential differences in noncardiac mortality between treatment strategies for chronic coronary syndromes.”

Eliano P. Navarese, MD, PhD, an associate professor of interventional cardiology at Nicolaus Copernicus University, Bydgoszcz, Poland, was the lead author of this study and Dr. Wijns was a coinvestigator. The study was published simultaneously in the Journal of the American College of Cardiology at the time of the EuroPCR meeting.

In the late-breaking session where these data were presented, there was a general consensus among invited panelists that the data are convincing. For example, Michael Joner, MD, PhD, director of early clinical trials, German Heart Centre, Munich, agreed that these data “resolve the issue.”

Bernard de Bruyne, MD, PhD, an interventional cardiologist associated with the Cardiovascular Center Aalst, Kraainem, Belgium, also agreed that these data argue convincingly against the concern raised by publication of ISCHEMIA-EXTEND, but he added that this controversy has raised an important issue.

“We should always be reporting all-cause mortality, not just cardiovascular mortality, in our clinical trials,” he said, emphasizing that extending all-cause survival, not just preventing cardiovascular-related events, should be recognized as the goal of invasive strategies.

In an editorial accompanying the publication, Dr. Harvey D. White, MD, Te Whatu Ora-Health New Zealand, Auckland, writes similarly that the current findings, “alert us to the importance of adjudicating causes of death in clinical trials.

“The current trial-level meta-analysis may seem to dispel concerns about increases in noncardiac and cardiovascular deaths seen in some revascularization trials, but paradoxically, it has raised the need for more and careful analysis of causes of death,” Dr. White notes. He feels the signal of increased noncardiac or noncardiovascular death in ISCHEMIA EXTEND and the REVIVED trials is something “that we should pay attention to and explore the possibility that increased radiation doses with PCI may cause increased rates of cancer.”

Further study, including longer follow-up, other datasets, and quality of life data including cognitive function and “patient-focused outcomes such as day alive out of hospital,” is needed, he concludes.

Dr. Navarese has received research grants from Abbott and Amgen and lecture fees/honoraria from Amgen, AstraZeneca, Bayer, Pfizer, and Sanofi-Regeneron. Dr. Wijns reports financial relationships with Argonauts, Corrib Core Laboratory, and Rede Optimus Research. Dr. Capodanno reports financial relationships with Amgen, Daiichi Sankyo, and Sanofi. Dr. de Bruyne and Dr. Joner report financial relationships with multiple pharmaceutical and device manufacturers. Prof. White, as the John Neutze scholar, is supported by the Green Lane Research and Educational Fund. Prof. White has received grant support paid to the institution and fees for serving on steering committees of multiple trials sponsored by various companies.

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