Clinical Research StudyOutcomes of Acute Myocardial Infarction in Patients with Influenza and Other Viral Respiratory Infections
Introduction
According to the Influenza Hospitalization Surveillance Network, overall laboratory-confirmed influenza-associated hospitalization during the 2017-2018 influenza season was more than double that of the previous year, with the highest rate in adults aged ≥ 65 years.1 Influenza infections result in substantial morbidity and mortality, particularly in elderly patients with multiple comorbidities.2, 3 In addition to acute respiratory failure, another major cause of poor outcomes in these patients is cardiovascular events.4 A number of prior observational studies have identified an association between influenza infection and acute myocardial infarction.4, 5, 6 An acute systemic inflammatory process during influenza infection might transiently increase the risk of cardiovascular events, including acute myocardial infarction and stroke.7, 8 It has been suggested that influenza virus itself can exert thrombotic effect and inflammatory process on atherosclerotic plaques in animal studies.9, 10 Furthermore, stress from acute illness might also contribute to ischemia in patients with preexisting cardiovascular disease.
Despite a number of studies in several areas of influenza and its effect on cardiovascular disease,7, 9, 10 information on outcomes of the patients who are admitted with acute myocardial infarction and concurrent influenza infection is scarce.4 Further understanding of the clinical outcomes of these patients during acute myocardial infarction admission is crucial to estimate the impact of influenza on these patients. In the present study, using a nationally representative sample, we aimed to determine the hospital outcomes of such patients, in comparison with the acute myocardial infarction patients who had no, or other, noninfluenza viral respiratory infections.
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Data Source
Data were obtained from the Agency for Healthcare and Research and Quality Healthcare Cost and Utilization Project’s National Inpatient Sample (NIS) from January 1, 2013 through December 31, 2014. The NIS is the largest publicly available all-payer inpatient health care database in the United States, yielding national estimates of hospital inpatient stays. The NIS approximates a 20% stratified sample of all discharges from the US hospitals, excluding rehabilitation and long-term acute care
Baseline Characteristics of the Study Population
From January 2013 through December 2014, there was a total of 1,884,985 admissions nationally for acute myocardial infarction. Influenza and other viral respiratory infections were diagnosed during the same admission in 9,885 and 11,485 patients, respectively, accounting for a total of 1.1% of patients (Figure 1). Patients with influenza and other viral respiratory infections were older, had higher proportion of females, and comorbidities, including systolic heart failure, atrial arrhythmia,
Discussion
From a large national database, we evaluated the outcomes of acute myocardial infarction in patients with influenza and other viral respiratory infections by comparing with the patients who had acute myocardial infarction alone using propensity scores. The in-hospital case fatality rate and other in-hospital outcomes were worst in the patients with concomitant influenza infection, but not in the patients with other viral respiratory infection when comparing with patients with acute myocardial
Conclusions
Acute myocardial infarction patients with concomitant influenza infection are at high risk for poor outcomes, with increased in-hospital mortality compared with patients who are hospitalized with acute myocardial infarction alone or with other viral respiratory infections. Further evaluation of coronary anatomy with invasive angiogram is underutilized in these patients. In light of the current study, prevention and prompt treatment of influenza infection should be given a priority, especially
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Funding: None.
Conflict of Interest: The authors have no disclosures pertinent to the manuscript.
Authorship: All authors have approved the contents of this manuscript and contributed to the study as detailed below:
PV and DK: Design, analysis, and interpretation of data, drafting of the manuscript with final approval of the manuscript submitted.
MM and KC: analysis and interpretation of data, manuscript critical revision for important intellectual content, with final approval of the manuscript submitted.
HVA, SA and PB: manuscript critical revision for important intellectual content, with final approval of the manuscript submitted.
RWS and AD: Conception, design, analysis, and interpretation of data and manuscript critical revision, with final approval of the manuscript submitted.