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Conflicting periprocedural MI definitions impact clinical practice, research

Journal of the American College of Cardiology
Reuters Health - 07/02/2022 - Among patients with chronic coronary syndrome (CCS), the presence and prognostic implications of periprocedural myocardial infarction (PPMI) vary tremendously, depending on which PPMI definition is utilized, researchers say.

"How we assess PPMI is essential for three reasons," Dr. Lorenz Raber of the University of Bern in Switzerland told Reuters Health by email. "First, it impacts on patient care following revascularization procedures; second, it is considered as a quality measure; and third, it is used to compare different revascularization strategies (e.g., surgery vs. stent) in research."

"We found that when applying the three widely accepted definitions, the frequency of PPMI numbers differed by a factor of 7... and the correlation with prognosis differed substantially," he said.

"The use of a PPMI definition that inflates the number of PPMI substantially without prognostic impact - i.e., the 4th Universal Definition of Myocardial Infarction (UDMI) - should not be used in routine clinical practice and research," he concluded.

As reported in the Journal of the American College of Cardiology, Dr. Raber and colleagues evaluated the frequency and impact of PPMI by using various definitions among patients with CCS undergoing percutaneous coronary intervention (PCI).

PPMI definitions included: the third and fourth UDMI, Academic Research Consortium-2 (ARC-2), and Society for Cardiovascular Angiography and Interventions (SCAI) criteria based on high-sensitivity troponin.

The primary endpoint was cardiac death at one year.

Among 4,404 patients (mean age, 69; 26%, women) with CCS enrolled in the Bern PCI registry, PPMI was observed in 18.0% of patients when defined by the third UDMI; 14.9% by the fourth UDMI; 2.0% by ARC-2, and 2.0% SCAI.

The authors note that "inflated numbers" of PPMI defined by the UDMI is primarily attributable to a low threshold of high-sensitivity troponins and broadly defined ancillary criteria, compared with the ARC-2 and SCAI definitions, which apply higher troponin cutoffs with more specific angiographic criteria.

Cardiac mortality at one year among patients with PPMI defined by the third UDMI was 2.9%; by the fourth UDMI, 3.0%; by ARC-2, 5.8%; and by SCAI, 10.0%. The ARC-2 (HR,3.90) and SCAI (HR, 7.66) were more prognostic compared with the third UDMI (HR, 1.76) and fourth UDMI (HR, 1.93).

Dr. Cian McCarthy of Massachusetts General Hospital in Boston, coauthor of a related editorial, commented in an email to Reuters Health, "PPMI is often used as a component of the composite MACE outcome of clinical trials. However, it is now under increasing scrutiny for several reasons."

"First, a few studies have suggested that spontaneous MI has a more adverse prognosis than PPMI, but they are considered equal in composite endpoints," he said. "Second, there are several definitions of PPMI and the incidence and prognosis may differ depending on the definition used and the context in which it occurred - e.g., PCI versus CABG. Lastly, it is not clear that PPMI is on the causal pathway for mortality - i.e., do therapies that reduce PPMI actually reduce mortality?"

"It is crucial that we figure these issues out quickly, as the inclusion of PPMI as an endpoint can have a significant impact on trial results," he noted. "A consensus needs to be made by the cardiovascular community, ideally supported by the major societies, on which definition to use, if any."

"If it is to be included as an endpoint, until further data emerge, one potential solution would be to use a hierarchical endpoint model where mortality and spontaneous MI are prioritized above PPMI," Dr. McCarthy concluded.

SOURCE: https://bit.ly/3uz1rLW and https://bit.ly/3uz1zeo Journal of the American College of Cardiology, online February 7, 2022.

By Marilynn Larkin

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