In this study of more than 10,000 residents of a large central New England metropolitan area hospitalized with AMI, older men and women were more likely to have developed AF and heart failure, and were more likely to have died during hospitalization and during the first 30-days after admission, compared with patients <65 years. Older men were also more likely to have developed cardiogenic shock compared with younger men. Among men, age differences in the risk of developing AF and cardiogenic shock have widened over time. Encouragingly, we noted a steady improvement in the majority of hospital outcomes examined in most age groups over the 20 year period under study, with a particularly marked improvement observed in the risk of developing cardiogenic shock in elderly but not in younger patients. While unknown, these latter findings may be due to the changing characteristics of patients hospitalized with AMI over time and/or to the more frequent use of cardiac catheterization and PCI in elderly patients.
Our results are consistent with the findings from previous studies which have shown that older patients hospitalized with AMI have a worse prognosis than younger patients.1,2,5,15
Older patients are more likely to have additional comorbidities present at the time of hospitalization for AMI which may increase their risk of developing clinically significant hospital complications and dying. Previous studies have shown that older patients are less likely to be treated with evidence-based cardiac medications and interventional procedures,4,21
which may have contributed to their greater risk of dying in the short-term. Other factors such as prolonged delay in seeking medical care,5,6
limited health care access, cognitive impairment, and frailty may also have played a role in the less favorable prognosis observed in older patients.
We found that age differences in the risk of developing new onset AF during hospitalization for AMI have widened during the past 20 years for men. On the other hand, differences in the risk of developing cardiogenic shock between men 65–74 years and men <65 years have widened over time but have narrowed for men ≥75 years. Our findings also showed that, despite the fact that the overall in-hospital death rates among patients with AMI have decreased from 17% in 1986/1988 to 9% in 2003/2005, age differences in short-term mortality have remained relatively unchanged over time among both men and women; the elderly remain at higher risk for dying than younger patients.
The present findings may be partially explained by the fact that while the use of effective treatment modalities have increased in all age groups over time,22,23
the prevalence of clinically significant comorbidities have increased over time3
, especially in older patients. These latter trends make the management of hospitalized patients all the more challenging and increase the risk for adverse outcomes. Inasmuch, physicians need to consider the greater use of these treatment modalities in older patients to improve their short-term outcomes. Indeed, it is possible that the more aggressive management of elderly patients with coronary interventional procedures led to their declining risk of cardiogenic shock, and improving hospital survival, during the period under study. The enhanced use of these treatment regimens may also result in greater quality of life in patients of all ages and improvements in long-term prognosis.
We also observed that the short-term death rates were much higher in younger women than in younger men, with these differences persisting in the most recently hospitalized study cohorts; there were no sex differences in the crude short-term death rates among older patients. This finding is consistent with the results of previous studies.6,11,24–26
The reasons for worse short-term outcomes in younger women hospitalized with AMI are unclear but may be partially explained by the fact that women have a higher prevalence of comorbid conditions than men, and differences in these and other important prognostic factors are likely to be more pronounced in younger than in older individuals.25
In addition, younger women have been shown to be less likely to be treated with effective cardiac medications.13,26
which can contribute to the worse outcomes noted in younger women. However, a previous study of patients enrolled in the National Registry of Myocardial Infarction suggested that differences in medical history, clinical severity of the infarction, and early management accounted only for about one third of the differences in early mortality observed between men and women hospitalized with AMI.6
The fact that men may be more likely to die out-of-hospital from coronary disease than women, and that this sex difference may be larger in younger than in older individuals,25
could contribute to higher in-hospital death rates in younger women hospitalized with AMI. Additional prospective studies need to be carried out to understand the reasons behind the greater risk of adverse outcomes noted in younger women and older individuals hospitalized with acute coronary disease.
Study Strengths and Limitations
The strengths of this study include its population-based design that captured all validated cases of AMI occurring among residents of the Worcester metropolitan area hospitalized at all Central Massachusetts medical centers over a 20-year period. On the other hand, the study population was predominantly white and the generalizability of our findings to other race/ethnic groups may be limited. We did not have information available on several patient-associated characteristics (e.g., socioeconomic status, psychological factors) which may have confounded some of the observed associations. Because patients who died before hospitalization for AMI were not included, our findings are only generalizable to patients hospitalized with AMI.
In conclusion, while encouraging declines in hospital death rates and in the occurrence of several important clinical complications have declined in men and women of all ages during the past 20 years, older men and women were more likely to experience adverse short-term outcomes after hospitalization for AMI than patients <65 years. More targeted treatment approaches during hospitalization for AMI for older patients are needed to improve their short-term prognosis.