Higher 5-Year Risk of Death With MINOCA vs Obstructive STEMI

STEMI patients presenting with nonobstructive coronary arteries (MINOCA)—but not those with takotsubo syndrome, myocarditis, or nonischemic cardiomyopathy, which are known MINOCA mimics—appear to have a higher risk of death in midterm follow-up than those with obstructive disease, according to new retrospective data.

In an analysis published online last week in JAMA Network Open, the 5-year mortality risk was nearly twofold higher in true MINOCA patients than in those with obstructive CAD (HR 1.93; 95% CI 1.06-3.53), investigators report.

“Traditionally, MINOCA and mimickers are thought to be less-lethal diseases,” lead author Odayme Quesada, MD (The Christ Hospital Health Network, Cincinnati, OH), told TCTMD. “Therefore, these patients are often not given a diagnosis, they don't receive the correct diagnostic test that exists for MINOCA, [and] they don't get the same treatment at discharge.”

One issue plaguing research is that the precise definition of MINOCA has been up for debate since the term’s introduction less than a decade ago. The American Heart Association defines it as coronary artery plaque disruption, epicardial coronary spasm, or coronary embolism/thrombosis and excludes mimics, but a European Society of Cardiology statement includes the conditions that also mimic MINOCA.

With these unclear definitions, it’s been challenging for physicians to identify and treat MINOCA, as well as to understand the long-term implications of the disease.

Harmony Reynolds, MD (NYU Grossman School of Medicine, New York, NY), who commented on the findings for TCTMD, said identifying the underlying cause of MI in patients with MINOCA is critically important because treatment will vary depending on etiology.

“Some patients who are initially diagnosed with MINOCA turn out not to have MI at all and instead to have an alternate diagnosis like myocarditis, takotsubo syndrome, or another nonischemic cardiomyopathy,” she said in an email. “Clearly, patients need to know if they had a heart attack or not.”

More Mortality With MINOCA

For the study, Quesada and colleagues included data from 8,560 consecutive patients (mean age 62 years; 30% female) presenting with STEMI at three Midwest institutions between March 2003 and December 2020. The population included 1.4% with MINOCA and 3.8% with MINOCA mimics, with both groups being less likely to be discharged on cardiac medications compared with those with obstructive disease. The median follow-up period was 7.1 years.

At 5 years, STEMI patients presenting with obstructive disease had a mortality rate (16%) similar to that in patients with MINOCA (18%) and MINOCA mimics (18%; P > 0.05 for both). However, in multivariable-adjusted analyses, compared with those with obstructive disease, the 5-year mortality risk was higher in those with MINOCA (HR 1.93; 95% CI 1.06-3.53), yet not significantly different in patients with MINOCA mimics (HR 1.08; 95% CI 0.79-1.49).

Compared against each other, MINOCA and MINOCA mimics had a statistically similar 5-year mortality risk on multivariable analysis (HR 1.65; 95% CI 0.68-4.01).

Cardiac MRI was used with varying frequency at each of the three study institutions. Notably, diagnosed MINOCA cases were more frequent (76%) at the site that routinely used such imaging than at the other two sites (42% and 57%; P for trend = 0.03).

Unexpected Findings

Quesada admitted the findings were not what she expected to see. “I thought we were going to find similarities when thinking about long-term mortality,” she said. “We were a bit surprised that there was almost a twofold higher risk in STEMI MINOCA compared to the obstructive disease.”

The traditional lack of testing for patients with MINOCA and mimics is likely the culprit for why so many of these patients fare worse than those with obstructive disease, Quesada said. “What happens is you don't arrive at a diagnosis. Therefore, you don't really know how to treat these patients,” she explained.

The findings should change practice in that clinicians may be more proactive in caring for patients with STEMI without obstructive disease, Quesada said. “We need to make sure we go that extra step, not only in the cath lab where we should be using intravascular imaging, but within the hospitalization—get that cardiac MRI, arrive at a diagnosis, give that patient the diagnosis, and then send them up the appropriate treatment,” she said. “We saw that these patients are at a higher mortality risk, and we hypothesize that if they were diagnosed and treated appropriately, the mortality would decrease.”

Future studies should look at how perhaps more-accurate diagnosis of MINOCA and mimics affects the rates of targeted treatment and ultimately outcomes, according to Quesada.

Similarly, Reynolds said she would like to see more intracoronary imaging studies in STEMI with no obstructive coronary arteries to better understand what proportion of the true MINOCA cases (without mimics) have plaque rupture versus coronary artery spasm.

These findings will encourage her to “continue to push for early cardiac MRI in patients with STEMI presentation who have no obstructive coronary arteries,” Reynolds added. “The earlier the MRI, the better the chance of making a specific diagnosis. However, later MRI is useful too, even a month later or more if needed based on other studies.”