Although acute myocardial infarction (AMI) occurs primarily in the elderly, this disease also affects young adults. Few studies have, however, presented data on relatively young patients hospitalized with AMI. The objectives of this population-based study were to examine recent trends in the magnitude, clinical characteristics, management, and in-hospital and long-term outcomes associated with ST-segment elevation myocardial infarction (STEMI) and non–ST-segment elevation myocardial infarction (NSTEMI) in patients aged 30 to 54 years. We reviewed the medical records of 955 residents of the Worcester (Massachusetts) metropolitan area aged 30 to 54 years who were hospitalized for an initial STEMI or NSTEMI in 6 biennial periods from 1999 to 2009 at 11 greater Worcester medical centers. From 1999 to 2009, the proportion of young adults hospitalized with an STEMI decreased from approximately 2/3 to 2/5 of all patients with an initial AMI. Patients with STEMI were less likely to have a history of heart failure, hypertension, hyperlipidemia, and kidney disease than those with NSTEMI. Both groups received similar effective medical therapies during their acute hospitalization. In-hospital clinical complications and mortality were low and no significant differences in these end points were observed between patients with STEMI and NSTEMI or with regard to 1-year postdischarge death rates (1.9% vs 2.8%). The present results demonstrate recent decreases in the proportion of relatively young patients diagnosed with an initial STEMI. Patients with STEMI and NSTEMI had similar in-hospital outcomes and long-term survival. Trends in these and other important outcomes warrant continued monitoring.
Using data from the population-based Worcester Heart Attack Study (WHAS), we examined overall differences and decade-long trends in the clinical characteristics, management, and in-hospital and long-term outcomes associated with ST-segment elevation myocardial infarction (STEMI) and non–ST-segment elevation myocardial infarction (NSTEMI) in young adults aged 30 to 54 years who were hospitalized with a first acute myocardial infarction (AMI) at all greater Worcester (Massachusetts) medical centers in 6 biennial periods from 1999 to 2009.
Methods
The WHAS is an ongoing population-based clinical investigation describing long-term trends in the incidence, hospital management practices, and death rates of greater Worcester, Massachusetts, residents hospitalized with AMI at all 11 metropolitan Worcester medical centers. For the present study, we limited our sample to adults aged 30 to 54 years who were hospitalized with an independently validated initial AMI during 1999, 2001, 2003, 2005, 2007, and 2009. These years were selected because of funding availability and because we were interested in the surveillance of acute coronary disease in this central Massachusetts population on a biennial basis. This study was approved by the Committee for the Protection of Human Subjects in Research at the University of Massachusetts Medical School.
The methods used in this coronary disease surveillance study have been described elsewhere in detail. In brief, the medical records of potentially eligible residents of central Massachusetts who were hospitalized with discharge diagnoses consistent with the possible presence of AMI at all central Massachusetts medical centers were identified through the review of computerized hospital databases. Based on the independent review of previous and current hospital medical records by trained nurse and physician abstractors, patients with a history of AMI were excluded from the present population, because we were interested in the descriptive epidemiology of patients with a first AMI in the present study. Diagnoses of STEMI and NSTEMI were made using standardized criteria. Since 2003, in the absence of electrocardiographic abnormalities, a diagnosis of NSTEMI was accepted when elevations in various cardiac biomarker assays, including troponin, were accompanied by typical clinical symptomatology and acute presentation.
Trained study physicians and nurses abstracted clinical, demographic, and treatment-related data from the medical records of patients with confirmed AMI. Receipt of cardiac medications, cardiac catheterization, percutaneous coronary intervention (PCI), and coronary artery bypass surgery, as well as development of important clinical complications during the patient’s index hospitalization, were determined using preestablished criteria. Survival status after hospital discharge was determined through a review of hospital records and a search of death certificates for residents of the Worcester metropolitan area. Follow-up was continued through 2011.
Short- and long-term outcomes in each period were examined by calculating in-hospital, 1-year, and 2-year case-fatality rates; trends in these end points were examined through the use of chi-square tests for trend. Logistic regression modeling was used to assess the significance of 1- and 2-year postdischarge all-cause death rates in patients with STEMI versus NSTEMI while controlling for several potentially confounding demographic and clinical characteristics of prognostic importance.
Results
A total of 955 residents of the Worcester metropolitan area aged 30 to 54 years were hospitalized with an initial confirmed AMI at all 11 medical centers in central Massachusetts during the 6 years under study. The average age of this population was approximately 47 years, and 3/4 of subjects were men ( Table 1 ). Overall, 52% of all young adults hospitalized for AMI were diagnosed with STEMI during the years under study. The percentage of patients with STEMI decreased significantly from 1999 to 2009. In 1999, approximately 2/3 of all initial AMIs in our young adult population were STEMI in nature, whereas by 2009, 2/5 of all first AMIs in young adults had evidence of electrocardiographic ST-segment elevation.
| Variable | STEMI | NSTEMI | ||||||
|---|---|---|---|---|---|---|---|---|
| Total (n = 501) | 1999/2001 (n = 209) | 2003/2005 (n = 162) | 2007/2009 (n = 130) | Total (n = 454) | 1999/2001 (n = 137) | 2003/2005 (n = 162) | 2007/2009 (n = 176) | |
| Age, yrs (mean ± SD) | 47.3 ± 5.1 | 47.3 ± 5.3 | 46.9 ± 5.3 | 48.0 ± 4.7 | 47.8 ± 5.2 | 48.1 ± 4.9 | 47.8 ± 5.1 | 47.6 ± 5.5 |
| Men | 397 (79.4) | 169 (80.9) | 129 (79.6) | 99 (76.2) | 342 (75.3) | 110 (80.3) | 101 (71.6) | 131 (74.4)* |
| White | 435 (93.2) | 185 (94.3) | 137 (91.3) | 113 (93.4) | 378 (88.5) | 118 (90.1) | 115 (88.5) | 145 (87.4)* |
| Prehospital delay (median, h) | 1.5 | 1.5 | 1.5 | 1.6 | 2.0 | 2.0 | 2.0 | 2.1 |
| Angina pectoris | 39 (7.8) | 26 (12.4) | 11 (6.8) | 2 (1.5) | 46 (10.1) | 16 (11.7) | 18 (12.8) | 12 (6.8) |
| Current smoker | 261 (52.1) | 98 (46.9) | 87 (53.7) | 76 (58.5) | 228 (50.2) | 66 (48.2) | 78 (55.3) | 84 (47.7)* |
| Diabetes mellitus | 93 (18.6) | 35 (16.8) | 34 (21.0) | 24 (18.5)* | 112 (24.7) | 28 (20.4) | 37 (26.2) | 47 (26.7)* |
| Heart failure | 19 (3.8) | 8 (3.8) | 8 (4.9) | 3 (2.3)* | 40 (8.8) | 11 (8.0) | 15 (10.6) | 14 (8.0) |
| Hyperlipidemia ∗ | 278 (55.5) | 105 (50.2) | 92 (56.8) | 81 (62.3) | 275 (60.6) | 75 (54.7) | 72 (51.1) | 128 (72.7)* |
| Hypertension † | 229 (45.7) | 88 (42.1) | 76 (46.9) | 65 (50.0)* | 254 (56.0) | 65 (47.5) | 83 (58.9) | 106 (60.2)** |
| Body mass index (kg/m 2 ) | ||||||||
| 25–29.9 | 177 (35.5) | 55 (26.3) | 65 (40.1) | 57 (43.9) | 138 (30.4) | 35 (25.6) | 43 (30.5) | 60 (34.1) |
| ≥30 | 245 (48.9) | 120 (57.4) | 75 (46.3) | 50 (38.5) | 244 (53.7) | 91 (66.4) | 66 (46.8) | 87 (49.4) |
| Presenting symptoms | ||||||||
| Abdominal pain | 19 (3.8) | 12 (5.7) | 5 (3.1) | 2 (1.5) | 21 (4.6) | 4 (2.9) | 8 (5.7) | 9 (5.1)** |
| Back pain | 82 (16.4) | 39 (18.7) | 28 (17.3) | 15 (11.5) | 63 (13.9) | 18 (13.1) | 24 (17) | 21 (11.9) |
| Chest pain | 429 (85.6) | 162 (77.5) | 147 (90.7) | 120 (92.3) | 376 (82.8) | 101 (73.7) | 118 (83.7) | 157 (89.2) |
∗ Hyperlipidemia: serum total cholesterol >240 mg/dl.
† Hypertension: systolic blood pressure >140 mm Hg and/or diastolic blood pressure >90 mm Hg.
Overall, patients with NSTEMI (n = 454) were more likely to be obese and to have a history of heart failure, hypertension, and hyperlipidemia compared with patients with STEMI (n = 501; Table 1 ). Subjects hospitalized for NSTEMI were less likely to have presented to all central Massachusetts hospitals with chest pain, left arm pain, and diaphoresis, whereas patients with STEMI tended to seek medical care sooner, after the onset of acute coronary symptoms.
In all patients, the proportion of those with a history of angina decreased markedly during the period under study, particularly in patients with STEMI ( Table 1 ). Patients with STEMI were also less likely to have presented with diabetes over time. In contrast, patients with NSTEMI had a marked increase in the prevalence of hypertension and hyperlipidemia during the years under surveillance.
There were no significant differences between our respective comparison groups in the proportion of patients who were prescribed each of the effective cardiac medications examined. Throughout the study period, all patients were increasingly more likely to be prescribed each of the examined evidence-based cardiac medications while admitted to all central Massachusetts hospitals ( Figure 1 ). A greater increase in the hospital use of angiotensin-converting enzyme inhibitors and/or angiotensin receptor blockers was noted in patients with STEMI over time, whereas a greater increase in the use of aspirin and β blockers was noted in patients with NSTEMI ( Figure 1 ).
Patients with STEMI were more likely to have undergone cardiac catheterization and a PCI during their index hospitalization compared with patients diagnosed with NSTEMI. The proportion of patients who underwent cardiac catheterization increased from 79% to 99% and from 70% to 91%, in patients with STEMI and NSTEMI, respectively, from 1999 to 2009. The proportion of patients receiving a PCI increased from 53% to 92% and from 39% to 67%, in patients with STEMI and NSTEMI, respectively, during the years under study ( Figure 2 ). When PCI was performed, door-to-balloon time was approximately 3 hours for patients with STEMI compared with 22 hours for patients hospitalized with NSTEMI.
There were no significant differences in the proportion of patients who developed several important hospital clinical complications, such as heart failure and atrial fibrillation, or who died during their index hospitalization, in patients with either an initial STEMI or NSTEMI ( Table 2 ). Patients with STEMI were more likely to have developed cardiogenic shock, atrial fibrillation, and heart failure than patients with NSTEMI who were more likely to have developed acute stroke during their index hospitalization at all greater Worcester medical centers ( Table 2 ).
| Complication | STEMI | p Value | NSTEMI | p Value | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Total (n = 501) | 1999/2001 (n = 209) | 2003/2005 (n = 162) | 2007/2009 (n = 130) | Total (n = 454) | 1999/2001 (n = 137) | 2003/2005 (n = 141) | 2007/2009 (n = 176) | |||
| Atrial fibrillation | 26 (5.2) | 12 (5.7) | 9 (5.6) | 5 (3.9) | 0.26 | 15 (3.3) | 7 (5.1) | 6 (4.3) | 2 (1.1) | 0.24 |
| Heart failure | 85 (17.0) | 42 (20.1) | 14 (8.6) | 29 (22.3) | 0.28 | 51 (11.2) | 20 (14.6) | 17 (12.1) | 14 (8.0) | 0.20 |
| Cardiogenic shock | 23 (4.6) | 12 (5.7) | 2 (1.2) | 9 (6.9) | 0.18 | 7 (1.5) | 5 (3.7) | 2 (1.4) | 0 | 0.18 |
| Death | 17 (3.4) | 6 (2.9) | 4 (2.5) | 7 (5.4) | 0.22 | 12 (2.6) | 5 (3.7) | 5 (3.6) | 2 (1.1) | 0.11 |
| Length of stay (median, days) | 3.0 | 4.0 | 3.0 | 3.0 | 0.27 | 3.0 | 3.0 | 3.0 | 3.0 | 0.88 |
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