A new, evidence-based definition of periprocedural myocardial infarction (MI) has been proposed by the Society for Cardiovascular Angiography and Interventions (SCAI) in an effort to link the definition more closely with prognosis, reports a position paper published in the October 22, 2013, issue of the Journal of the American College of Cardiology.

Issam D. Moussa, MD, of the Mayo Clinic (Jacksonville, FL), who coauthored the SCAI statement, told TCTMD in a telephone interview that any definition is a moving target.

“We believe this new definition reflects the current evidence with how post-PCI MI should be defined,” he said. “That doesn’t mean a year from now, or even 6 months from now, there won’t be a study with 40,000 patients that will prove [the value] of a different definition. We should do more rigorous clinical trials.”

Greater Emphasis on CK-MB

An editorial accompanying the paper by Harvey White, DSc, of Auckland City Hospital (Auckland, New Zealand), outlines key differences between the third universal definition of periprocedural MI, most recently revised in 2012, and the SCAI proposal. Compared with the 2012 definition, the new version focuses more closely on CK-MB and does not consider symptomatology or angiographic complications. It also utilizes signs of myonecrosis instead of myocardial injury (table 1).

Table 1. Proposed SCAI Definition and Key Differences from Universal Definition

According to Sorin J. Brener, MD, of Weill Cornell Medical College (New York, NY), the new definition of periprocedural MI shifts the focus away from whether any myocardial damage has occurred to the more prognostically and clinically relevant question: “Should we be worried about it?”

“When we make a diagnosis of a complication after any procedure, the complication has to mean something to the patient,” Dr. Moussa said, emphasizing that data are needed to support whether a patient diagnosed with periprocedural MI will actually be worse off as a result. Knowing which patients have a poorer prognosis, he added, can help allocate resources, such as closer monitoring and further testing, to those patients most likely to benefit.

“The newer definition standardizes the way we measure and confirm the presence of MI,” Joseph Alpert, MD, of the University of Arizona Medical Center (Tucson, AZ) told TCTMD in an e-mail communication. “It is much more accurate compared with earlier tests and hence benefits patients by giving a more accurate diagnosis leading to more accurate therapy.”

Dr. Alpert helped develop the earlier universal definition of MI, which was first issued by a joint ESC/ACC/AHA/WHF task force in 2007.

“Practicing interventionalists need to know about the new definition so that they can track their rate of periprocedural MI,” he continued, adding, “If they have a high rate of periprocedural MI, then they need to reevaluate what they are doing in order to decrease this rate of MI and myocardial injury. I believe that in the future, it will be required to monitor these events as part of a quality assurance program.”

Relevance for Research

“Very few hospitals are using the universal definition for MI,” Dr. Moussa reported. “Most people believe that using the five times normal [troponin cutoff] may overestimate the incidence of MI. Some would argue that adding clinical angiographic data would make it more specific, which is true, but the majority of evidence does not account for clinical angiographic factors. This is an important gap in the evidence. Going forward, when we collect biomarkers, we need to collect ECG and angiographic clinical data in order to understand how much value these add to the biomarkers.”

A new definition is “important for the research community because many of the endpoints for clinical trials, [notably] MI after procedure, have low specificity, which can potentially skew the results of the trial,” said Dr. Brener. A more prognostically-linked endpoint such as the proposed new definition can improve researchers’ ability to identify interventions that will have meaningful benefits for patients.

However, Dr. White cautions against relying solely on SCAI’s definition.

“The rationale for the SCAI definition has been well articulated by its authors and may be appropriate in an individual trial, but it should not supplant the universal definition of MI. The metrics for both should be available if the SCAI definition is used,” he notes in the editorial. “Strict systematic implementation of the universal definition of MI with emphasis on the importance of a stable or falling troponin baseline will enhance specificity and will allow a rigorous assessment of new interventions.”

While documenting angiographic complications is challenging, he agrees, the added information “makes the elevation of biomarkers clinically relevant and likely to impact prognosis.”

Note: Study coauthors Gregg W. Stone, MD, and Roxana Mehran, MD, are faculty members of the Cardiovascular Research Foundation, which owns and operates TCTMD.

2. White H. Avatar of the universal definition of periprocedural myocardial infarction [editorial]. J Am Coll Cardiol. 2013;62:1571-1574.

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