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N Engl J Med. 2018 Jan 25;378(4):345-353. doi: 10.1056/NEJMoa1702090.

Acute Myocardial Infarction after Laboratory-Confirmed Influenza Infection.

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From the Institute for Clinical Evaluative Sciences (J.C.K., K.L.S., M.A.C., H.C., D.T.K., L.C.R.), Public Health Ontario (J.C.K., K.L.S., N.S.C., L.C.R., J.B.G.), Dalla Lana School of Public Health (J.C.K., K.L.S., N.S.C., A.J.M., L.C.R.), and the Departments of Family and Community Medicine (J.C.K.) and Laboratory Medicine and Pathobiology (N.S.C., K.K., A.J.M., A.S., J.B.G.), University of Toronto, University Health Network (J.C.K.), North York General Hospital (K.K.), Sunnybrook Health Sciences Centre (D.T.K., A.S.), Sinai Health System (A.J.M.), and the Hospital for Sick Children (J.B.G.), Toronto, Children's Hospital of Eastern Ontario (T.K., D.M.) and the Department of Pathology and Laboratory Medicine, University of Ottawa (T.K.), Ottawa, William Osler Health System, Brampton, ON (D.C.R.), McMaster University, Hamilton, ON (M.S.), London Health Sciences Centre, London, ON (G.Z.), and the Newfoundland and Labrador Public Health Laboratory, St. John's (G.Z.) - all in Canada.



Acute myocardial infarction can be triggered by acute respiratory infections. Previous studies have suggested an association between influenza and acute myocardial infarction, but those studies used nonspecific measures of influenza infection or study designs that were susceptible to bias. We evaluated the association between laboratory-confirmed influenza infection and acute myocardial infarction.


We used the self-controlled case-series design to evaluate the association between laboratory-confirmed influenza infection and hospitalization for acute myocardial infarction. We used various high-specificity laboratory methods to confirm influenza infection in respiratory specimens, and we ascertained hospitalization for acute myocardial infarction from administrative data. We defined the "risk interval" as the first 7 days after respiratory specimen collection and the "control interval" as 1 year before and 1 year after the risk interval.


We identified 364 hospitalizations for acute myocardial infarction that occurred within 1 year before and 1 year after a positive test result for influenza. Of these, 20 (20.0 admissions per week) occurred during the risk interval and 344 (3.3 admissions per week) occurred during the control interval. The incidence ratio of an admission for acute myocardial infarction during the risk interval as compared with the control interval was 6.05 (95% confidence interval [CI], 3.86 to 9.50). No increased incidence was observed after day 7. Incidence ratios for acute myocardial infarction within 7 days after detection of influenza B, influenza A, respiratory syncytial virus, and other viruses were 10.11 (95% CI, 4.37 to 23.38), 5.17 (95% CI, 3.02 to 8.84), 3.51 (95% CI, 1.11 to 11.12), and 2.77 (95% CI, 1.23 to 6.24), respectively.


We found a significant association between respiratory infections, especially influenza, and acute myocardial infarction. (Funded by the Canadian Institutes of Health Research and others.).

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