Clinical Characteristics, Outcomes, and Epidemiological Trends of Patients Admitted With Type 2 Myocardial Infarction

Abstract

Background: Type 2 myocardial infarction (T2MI) was first established as a unique entity in 2007. However, its clinical features are not well characterized. This study aimed to determine the clinical characteristics, predictors of mortality, and hospitalization trends of patients with T2MI.

Methods: The National Inpatient Sample database was queried for patients hospitalized in the United States with T2MI (January 2018 to December 2019). Data were used to assess baseline characteristics, primary diagnoses, predictors of mortality, and hospitalization and mortality trends of T2MI.

Results: During the 24-month study period, 1,789,485 (76%) patients were admitted with type 1 myocardial infarction (T1MI) and 563,695 (24%) were admitted with T2MI. Patients with T2MI were more likely to be older (71 vs 68 years; P < .001) and female (47.5% vs 38.3%; P < .001), with fewer comorbidities related to coronary atherosclerosis. African Americans were the only race with a significantly higher rate of hospitalization for T2MI (15.9% vs 11.6%; P < .001). The predictors of mortality were similar in both the T2MI and T1MI cohorts. Sepsis (23.47%), hypertensive heart disease (15.35%), and atrial arrhythmias (4.49%) were the most common principal diagnoses for T2MI. T2MI hospitalizations trended consistently upward during the study period. Monthly in-hospital mortality rates were consistently higher for T2MI versus T1MI (P < .001).

Conclusions: T2MI is a unique and heterogeneous clinical entity. Despite increased awareness, there is a lack of standardization of medical management and timing for revascularization, even as mortality rates remain persistently elevated compared with T1MI. Certain demographics, including African Americans, may be disproportionately affected.

Keywords: National Inpatient Sample; mortality; outcomes; type 2 myocardial infarction.

Graphical abstract

Figure. 1

Patient population selection. The National Inpatient Sample database was queried over a 24-month period (January 2018 to December 2019) for all patients admitted with MI and divided into T1MI (which includes all STEMI and NSTEMI codes) and T2MI (which does not have a subdivision within ICD-10-CM diagnostic codes). ICD-10-CM, International Classification of Diseases, Tenth Edition, Clinical Modification; MI, myocardial infarction; NSTEMI, non–ST-elevation myocardial infarction; STEMI, ST-elevation myocardial infarction; T1MI, type 1 myocardial infarction; T2MI, type 2 myocardial infarction.

Figure. 2

Most common primary admission diagnoses among admitted patients with type 2 myocardial infarction. Sepsis was the most common primary diagnosis associated with type 2 myocardial infarction, followed by hypertensive heart disease and atrial arrhythmias.

Figure. 3

Adjusted predictors of all-cause mortality among patients with type 2 myocardial infarction. Similar to the T1MI cohort, mortality in this group was much more strongly associated with noncardiovascular conditions such as chronic liver and renal disease and cancer. AKI, acute kidney injury; CABG, coronary artery bypass graft; PCI, percutaneous intervention.

Figure. 4

Observed trends in monthly hospitalizations for MIs and the proportion of hospitalizations comprising T2MIs. Total hospitalizations for MI (A) trended up at a seasonally adjusted rate of 0.26% per month and the percent of total hospitalizations comprised of T2MI (B) admissions over the 24-month study period. The percent of admissions comprising T2MIs consistently increased over the study period. MI, myocardial infarction; T1MI, type 1 myocardial infarction; T2MI, type 2 myocardial infarction.

Central Illustration

Comparison of characteristics, outcomes, and trends in hospitalization and mortality in patients with type 1 myocardial infarction (T1MI) and type 2 myocardial infarction (T2MI). Trends in hospitalization for T1MI (top) and T2MI (bottom) during the 24-month study period. As shown in the graphs, the number of hospitalizations for T2MI saw a clear trend upward in contrast to T1MI hospitalizations. CAD, coronary artery disease; NSTEMI, non–ST-elevation myocardial infarction; STEMI, ST-elevation myocardial infarction.