Objective To identify differences in prevalence, demographics, clinical features and outcomes for type 1 myocardial infarction (T1MI) and type 2 myocardial infarction (T2MI) in a cohort of patients presenting to the Emergency Department (ED) with chest pain.
Methods This was a post hoc analysis of data collected from two prospective studies. Data were collected between November 2008 and February 2011 for the first study, and between February 2011 and March 2014 for the second. Participants were patients presenting to the ED with symptoms suggestive of acute coronary syndrome (ACS). The outcome was 30-day diagnosis; classified into T1MI, T2MI or non-MI. Descriptive statistics were used to compare the demographics, clinical history and presenting symptoms across diagnoses (T1MI, T2MI and non-MI). Cumulative mortality over 1 year was compared for T1MI and T2MI.
Results 147 patients (6.3%; 95% CI 5.3% to 7.3%) were classified as T1MI and 52 (2.2%; 95% CI 1.7% to 2.9%) were classified as T2MI. T2MIs were more likely to be female (OR 4.71, 95% CI 2.28 to 9.76), have an abnormal but non-ischaemic ECG (OR 2.95, 95% CI 1.45 to 6.00), report prior hypertension (OR 2.83, 95% CI 1.35 to 6.12), have tachycardia (OR 9.26, 95% CI 3.08 to 30.77) and pain at rest (OR 3.04, 95% CI 1.28 to 8.02) compared with T1MI. One-year mortality was similar between T1MI and T2MI (9% and 14.6%, respectively, p=0.37).
Conclusions T2MIs comprised one quarter of all MIs diagnosed in the ED. Among patients presenting to the ED with symptoms of ACS, symptoms do not allow clinicians to reliably differentiate patients with T1MI and T2MI. Prior hypertension, tachycardia and abnormal non-ischaemic ECGs are seen more often in T2MI compared with T1MI. One-year mortality was substantial in patients with T1MI and T2MI, but low power precludes conclusions about mortality differences between groups.
- acute myocardial infarction
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Contributors JG, TA and LC conceived and designed the study. JG, TH, WP and LC were involved in acquisition of data. JG analysed the data, WP, CM, YS and TN assisted with study design and interpretation of the data. JG and LC drafted the work and all authors revised the manuscript critically for important intellectual content.
Funding The study has been supported by a grant from the Emergency Medicine Foundation, who played no role in the design and conduct of the study, the study analyses, the drafting and editing of the manuscript or its final content.
Competing interests CM has received research support from the Swiss National Science Foundation, the Swiss Heart Foundation, Abbott, Alere, Astra Zeneca, Biomerieux, Beckman Coulter, Brahms, Nanosphere, Roche, Siemens, Singulex, Sphingotec, 8sense, Nanosphere, and the Department of Internal Medicine, University Hospital Basel, as well as speaker/consulting honoraria from Abbott, Alere, Astra Zeneca, Biomerieux, BG Medicine, BMS, Brahms, Cardiorentis, Daiichi Sankyo, Novartis, Radiometer, Roche, Sanofi, Siemens, and Singulex. WP is a consultant for Hospira/Pfizer outside the submitted work. LC reports grants from Roche and Beckmans; grants, consultancy fees, and personal fees from Abbott Diagnostics; grants and consultancy fess from Siemens; grants from Radiometer; personal fees from AstraZeneca; and personal fees from Novartis outside of the submitted work.
Ethics approval The study protocols were approved by the Human Ethics and Research committee (HREC 2008/101 and HREC/10/QRBW/403) and complied with the Declaration of Helsinki.
Provenance and peer review Not commissioned; externally peer reviewed.
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