June 06, 2018
3 min read

Differences between type 2 vs. type 1 MI may affect non-STEMI metrics

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Sameer Arora

Patients with type 2 MI are different from those with type 1 MI, and it may make sense to exclude them from non-STEMI quality metrics, according to a study published in the Journal of the American Heart Association.

“Although there has been widespread acceptance of the concept of type 2 MI, the ICD coding system did not recognize type 2 MI as a separate entity until October 2017. The impact of type 2 MI on hospital-level MI outcomes has not been studied as type 2 MI has been categorized under the general umbrella of non-STEMI,” Sameer Arora, MD, cardiovascular disease fellow and MPH candidate in epidemiology at the University of North Carolina, told Cardiology Today. “Compounding this was the fact that guidelines-based post-acute coronary syndrome treatment was expected to be followed in all patients with a diagnosis of MI. The use of guideline-based ACS medications — aspirin, statins and beta-blockers — in every case of type 2 MI may be inappropriate. The purpose of this study, therefore, was to assess differences in patient characteristics, treatment and mortality between type 2 and type 1 MI patients, and evaluate their potential impact on hospital-level MI metrics and implications for quality and public reporting.”

Arora and colleagues performed a single-center retrospective analysis of 1,318 patients discharged with a diagnosis of non-STEMI in 2013 and 2014. Patients were stratified by type 1 MI or type 2 MI by using the third universal definition of MI.

In the cohort, 1,039 patients met the third universal definition of non-STEMI, and 25.4% of them had type 2 MI, according to the researchers.

Compared with those with type 1 MI, patients with type 2 MI were older (P < .0001), had more chronic kidney disease (P = .003) and had lower peak troponin levels (P < .0001), according to the researchers.

Patients with type 2 MI had higher rates of in-hospital mortality (17.4% vs. 4.7%; P < .0001) and were more likely to die of non-CV causes (71.7% vs. 25%; P < .0001) compared with those with type 1 MI, Arora and colleagues wrote.

After adjustment for patient characteristics and discharge medications, the type 2 MI group had greater risk for death than the type 1 MI group at 30 days (RR = 3.63; 95% CI, 1.61-7.88) and 1 year (RR = 1.98; 95% CI, 1.44-2.73) after discharge.

“Our results show that type 2 MI has a significantly higher mortality than the plaque rupture type 1 MI and has a significant impact on overall non-STEMI mortality,” Arora told Cardiology Today. “In our study, type 2 MI represented only 25% of all non-STEMI patients but was responsible for over 50% of all inpatient non-STEMI deaths, the majority due to noncardiovascular causes. Patients with type 2 MI are discharged less frequently on medications as part of acute coronary syndrome core measures, which may impact the overall rates at which the patients are discharged on these medications in a non-STEMI population.”


CV-related readmissions were lower in the type 2 MI group at 30 days (RR = 0.49; 95% CI, 0.12-2.06), according to the researchers.

“Type 2 MI may skew MI metrics at different institutions and leads to an inaccurate assessment of quality and performance measures by MI quality review programs on patient populations that the metrics were not designed for and result in inappropriate penalties for health care providers,” Arora said in an interview. “It seemed prudent to categorize type 2 MI patients separately, instead of under the general umbrella of non-STEMI, and exclude these patients from acute MI quality metrics. Therefore, type 2 MI was given a separate ICD code in late 2017. In the future, it will be crucial to better understand how we can improve outcomes in this high-risk type 2 MI population.” – by Erik Swain

For more information:

Sameer Arora, MD, can be reached at saror@email.unc.edu.

Disclosures: The authors report no relevant financial disclosures.