Cardiologists Weigh in on New Universal Definition of Myocardial Infarction

Major cardiology associations joined forces to update the 2012 universal definition of myocardial infarction and standardize what constitutes a heart attack.

Developed by the European Society of Cardiology (ESC), the American College of Cardiology (ACC), the American Heart Association and the World Heart Federation, the fourth universal definition of myocardial infarction differentiates between myocardial infarction and myocardial injury while offering guidance on how to incorporate emerging imaging techniques and high-sensitivity troponin assays. 

Three cardiologists who commented to Cardiovascular Business on the definition singled out the new section highlighting the difference between myocardial infarction and myocardial injury without acute ischemia. Both may result in a troponin reading above the 99th percentile upper reference limit—which has traditionally been used to rule-in or rule-out myocardial infarction—but only certain cases represent heart attacks.

Educational tool for teams 

Richard Chazal, MD, medical director of the Heart and Vascular Institute at Lee Health in Fort Myers, Fla., and an ACC past president, says he plans to use the new definition to educate emergency department physicians, hospitalists and cardiologists. He predicts clinicians will use the definition document’s “Model for Interpreting Myocardial Injury” flowchart to distinguish among type 1 myocardial infarction, type 2 myocardial infarction, acute myocardial injury and chronic myocardial injury—all of which could have troponin values above the 99th percentile upper reference limit (Eur Heart J, online Aug. 25, 2018). 

“There’s been a tendency in the past to say elevated troponin means a heart attack, and this helps further clarify that’s not the case,” Chazal says. “Elevated troponin means something is going on with the myocardium, and it’s up to you to combine that along with clinical information to actually make the real diagnosis.”

Properly diagnosing and coding for cardiovascular conditions has become increasingly important as patient outcomes are now monitored more closely in value-based payment models, Chazal adds. And ruling out acute myocardial infarction earlier could save patients from expensive and unnecessary testing when they aren’t at high risk in the short term. 

“That doesn’t mean they aren’t going to be followed up for further evaluation, but it means they may be saved additional workup that might not change their outcomes early in the course of their event,” he explains.

Salim Hayek, MD, and Richard Kovacs, MD, both note the new definition may be more helpful for members of the care team other than cardiologists. 

“The decision making is complex, and the role of the practicing cardiologist is not only to implement the definition in their own clinical practice, but to succinctly communicate the new definitions to other members of the cardiovascular care team and non-cardiologists who may be making decisions on patients with acute coronary syndromes,” Kovacs, an Indianapolis-based cardiologist and vice president of the ACC, wrote in an email. “I would not simplify the document, but we need to simply communicate the concepts.”

Hayek, an assistant professor at the University of Michigan Frankel Cardiovascular Center, says the new definition may not change cardiologists’ processes, but will be “tremendously helpful for non-cardiologist physicians on the front lines of managing chest pain, such as internists, emergency department physicians and family physicians, as well as nurse practitioners and physician assistants, in contextualizing and interpreting elevations in cardiac enzymes.” 

Troponin tests still challenging

Hayek and Kovacs agree there are still hurdles to incorporating new-generation troponin assays into local practices, including identifying where they fit into the workflow and the most cost-effective usage strategies.

The concept of myocardial injury “will allow for a more nuanced classification of these patients,” but must be aligned with coding efforts in the hospital, says Kovacs. “I think the larger issues will be at the system level, where our clinical registries, such as the NCDR-Chest Pain-MI registry, will be increasingly important to track any changes in the patterns of care.”