Non-ST-elevation myocardial infarction in the United States: contemporary trends in incidence, utilization of the early invasive strategy, and in-hospital outcomes

Abstract

Background: There has been a paradigm shift in the definition of timing of early invasive strategy (EIS) for patients admitted with non-ST-elevation myocardial infarction (NSTEMI) in the last decade. Data on trends of EIS for NSTEMI and associated in-hospital outcomes are limited. Our aim is to analyze temporal trends in the incidence, utilization of early invasive strategy, and in-hospital outcomes of NSTEMI in the United States.

Methods and results: We analyzed the 2002-2011 Nationwide Inpatient Sample databases to identify all patients ≥40 years of age with the principal diagnosis of acute myocardial infarction (AMI) and NSTEMI. Logistic regression was used for overall, age-, sex-, and race/ethnicity-stratified trend analysis. From 2002 to 2011, we identified 6 512 372 patients with AMI. Of these, 3 981 119 (61.1%) had NSTEMI. The proportion of patients with NSTEMI increased from 52.8% in 2002 to 68.6% in 2011 (adjusted odds ratio [OR; per year], 1.055; 95% confidence interval [CI], 1.054 to 1.056) in the overall cohort. Similar trends were observed in age-, sex-, and race/ethnicity-stratified groups. From 2002 to 2011, utilization of EIS at day 0 increased from 14.9% to 21.8% (Ptrend<0.001) and utilization of EIS at day 0 or 1 increased from 27.8% to 41.4% (Ptrend<0.001). Risk-adjusted in-hospital mortality in the overall cohort decreased during the study period (adjusted OR [per year], 0.976; 95% CI, 0.974 to 0.978).

Conclusions: There have been temporal increases in the proportion of NSTEMI and, consistent with guidelines, greater utilization of EIS. This has been accompanied by temporal decreases in in-hospital mortality and length of stay.

Keywords: early invasive strategy; in‐hospital mortality; non‐ST‐elevation myocardial infarction; temporal trends.

Figure 1.

Temporal trends in incidence of non‐ST‐elevation myocardial infarction (STEMI). A, NSTEMI (%) was calculated as the number of patients with NSTEMI divided by the number of patients with acute myocardial infarction (AMI) per year×100; P_trend<0.001. B, Trends in NSTEMI presented as unadjusted and adjusted odds ratio and 95% confidence interval (CI) for each year relative to 2002 (reference year). Regression model adjusted for demographics, hospital characteristics, and 29 Elixhauser and other clinically relevant comorbidities. 95% CIs are depicted, but are too narrow to be visualized outside the marker width.

Figure 2.

Age, sex, and race/ethnicity specific trends in incidence rates of non‐ST‐elevation myocardial infarction. A, Age stratified; P_trend<0.001, (B) sex stratified; P_trend<0.001, and (C) race/ethnicity stratified; P_trend<0.001. AMI indicates acute myocardial infarction; NSTEMI, non‐ST‐elevation myocardial infarction.

Figure 3.

Trends in utilization of early invasive strategy for non‐ST‐elevation myocardial infarction. A, Early invasive strategy at day 0; P_trend<0.001. B, Trends in early invasive strategy at day 0 presented as unadjusted and adjusted odds ratio and 95% confidence interval (CI) for each year relative to 2002 (reference year). Regression model adjusted for demographics, hospital characteristics, and 29 Elixhauser and other clinically relevant comorbidities. C, Early invasive strategy at day 0 or 1; P_trend<0.001. D, Trends in early invasive strategy at day 0 or 1 presented as unadjusted and adjusted odds ratio and 95% confidence interval (CI) for each year relative to 2002 (reference year). Regression model adjusted for demographics, hospital characteristics, and 29 Elixhauser and other clinically relevant comorbidities. 95% CIs are depicted, but are too narrow to be visualized outside the marker width. NSTEMI indicates non‐ST‐elevation myocardial infarction.

Figure 4.

Age, sex, and race/ethnicity specific trends in utilization of early invasive strategy (EIS) for non‐ST‐elevation myocardial infarction. A, Age stratified, EIS day 0; P_trend<0.001, (B) sex stratified, EIS day 0; P_trend<0.001, (C) race/ethnicity stratified, EIS day 0; P_trend<0.001, (D) age stratified, EIS day 0 or 1; P_trend<0.001, (E) sex stratified, EIS day 0 or 1; P_trend<0.001, and (F) race/ethnicity stratified, EIS day 0 or 1; P_trend<0.001. NSTEMI indicates non‐ST‐elevation myocardial infarction.

Figure 5.

Trends in in‐hospital mortality in patients with non‐ST‐elevation myocardial infarction. A, In‐hospital mortality (%) was calculated as the number of patients who died during the hospitalization divided by the number of patients with NSTEMI per year×100; P_trend<0.001. B, Trends in in‐hospital mortality presented as unadjusted and adjusted odds ratio (OR) and 95% confidence interval (CI) for each year relative to 2002 (reference year). Regression model adjusted for demographics, hospital characteristics, and 29 Elixhauser and other clinically relevant comorbidities. NSTEMI indicates non‐ST‐elevation myocardial infarction.

Figure 6.

Age, sex, race/ethnicity, and utilization of invasive strategy‐specific trends in in‐hospital mortality in patients with non‐ST‐elevation myocardial infarction. A, Age stratified, (B) sex stratified, (C) race/ethnicity stratified, and (D) stratified according to utilization of invasive strategy (P_trend<0.001 for all). No EIS was defined as patients who did not receive coronary angiography with intent to revascularize within day 0 or 1. EIS indicates early invasive strategy.

Figure 7.

Temporal trends in length of stay, in days. A, Overall, (B) age, (C) sex, (D) race/ethnicity, and (E) timing of invasive strategy (P_trend<0.001 for all).

Figure 8.

Temporal trends in cost of stay, in U.S. dollars. (A) Overall, (B) age, (C) sex, (D) race/ethnicity, and (E) timing of invasive strategy (P_trend<0.001 for all).