The low accuracy of the non‐ST‐elevation myocardial infarction electrocardiograph criteria of the fourth universal definition of myocardial infarction

Background: The electrocardiograph has been integral to the diagnosis of acute coronary syndromes since the mid‐20th Century and is an important initial investigation that chest pain patients undergo on presentation to the Emergency Department. The Fourth Universal Definition of Myocardial Infarction recommends using dichotomous cut‐offs to identify ischaemic electrocardiographs. Objectives: We aimed to summarise the existing knowledge to inform emergency clinicians about the diagnostic accuracy of the new guidelines. Methods: We performed a systematic review and a narrative analysis due to the heterogeneity of the studies. Results: We were able to obtain diagnostic characteristics for 10 papers. The ST‐depression criteria were highly specific but poorly sensitive in five papers, with a specificity of 97.2%–99.3% and a sensitivity of 16.6%–20.0%. The remaining papers reported a higher sensitivity of 25.7%–58.6% but a lower specificity of 86.0%–91.2%. T wave inversion demonstrated poor specificity; the papers that looked at 0.1 mV T wave inversion demonstrated a sensitivity of 26.9%–46.8% and a specificity of 68.6%–86.4%. Conclusion: The heterogeneous evidence database demonstrates that the Fourth universal definition's diagnostic performance varies wildly. Apart from two outlying papers, ST‐depression has suboptimal sensitivity but high specificity. T wave inversion appears to be more sensitive yet less specific.