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.