Objectives: To describe the presenting characteristics and risk stratification of patients presenting to the emergency department with chest pain who have a normal initial troponin level followed by a raised troponin level within 12 h (evolving myocardial infarction (EMI)).
Methods: Data from the Internet Tracking Registry for Acute Coronary Syndromes (i*trACS), a registry of patients presenting with undifferentiated chest pain, were used. This analysis included patients without ST segment elevation with at least two troponin assay results ⩽12 h apart. Patients were stratified into three groups: EMI (initial troponin assay negative, second troponin assay positive), non-ST elevation myocardial infarction (NSTEMI) (initial troponin assay positive) and no MI (all troponin assays negative).
Results: Of 4136 eligible patients, 5% had EMI, 8% had NSTEMI and 87% had no MI. Patients with EMI were more similar to those with NSTEMI than those with no MI with respect to demographic characteristics, presentation, admission patterns and revascularisation. The initial ECG in patients with EMI was most commonly non-diagnostic (51%), but physicians’ initial impressions commonly reflected MI, unstable angina or high-risk chest pain (76%). This risk assessment was followed by a high rate of critical care admissions (32%) and revascularisation (percutaneous coronary intervention 17%) among patients with EMI.
Conclusion: Patients with EMI appear similar at presentation to those with NSTEMI. Patients with EMI are perceived as being at high risk, evidenced by similar diagnostic impressions, admission practices and revascularisation rates to patients with NSTEMI.
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Competing interests: CDM: research funding: Millennium, Schering-Plough, Biosite, Heartscape Technologies, Breathquant, Aventis Pharmaceuticals, Inovise Medical; consultant: Medicines Co, Bristol Myers Squibb/Sanofi Pharm Partnership, Molecular Insight; speaker: Genentech. GJF: research funding: Biosite, Heartscape Technologies; advisory board, Inverness Medical; speaker: Biosite. CJL: research funding: Abbott. KWM: (research funding from all of the following, consultant/speaker for those marked with asterisk): Abbott Vascular, Alexion*, Amgen*, AstraZeneca, Bayer*, BMS, Boston Scientific, Cardiokinetix, Cierra, Cordis, Conor, Corgentech, GE Medical Systems, Genentech*, Guidant, Johnson & Johnson*, Lilly, Medtronic, Merck, Novartis*, Ortho-Biotech, Procter & Gamble*, Sanofi-Aventis*, Sanofi Synthelabo*, Schering-Plough*, Scios*, Sicel Technologies, The Medicines Company*. WFP: research funding: Abbott, Biosite, Brahms, Heartscape, Inovise, Iverness Medical; consultant: Abbott, Beckman-Coulter, Biosite, Inovise, Iverness Medical, Ortho Clinical Diagnostics; speaker: Abbott, Biosite, Ortho Clinical Diagnostics. CVP: consultant: Schering Plough, Sanofi-Aventis, The Medicines Co, Bristol Myers Squibb; speaker: Schering Plough, Sanofi-Aventis; direct research support from GlaxoSmithKline, Sanofi-Aventis. JEH: ad boards, research funding, and consulting, speakers’ bureau with honoraria: GlaxoSmithKline, The Medicines Company, Sanofi-Aventis, Scios, Biosite, Ethicon, Astra-Zeneca, Protein Design Labs, Siemens. DBD: research support: Biosite, Inovise; speaker: Sanofi-Aventis, Bristol Myers Squibb; consultant: Astellas, Bristol Myers Squibb, Sanofi, The Medicines Co. WBG: research grant support: Abbott POC/i-STAT, Schering Plough, Sanofi-Aventis, Bristol-Myers Squibb (significant); ownership interests: Inovise, Matryx Group, Siloam (modest); consultant/advisory board: Heartscape Technologies; ArgiNOx; Astellas (modest). JWH: speaker: Sanofi-Aventis, Schering Plough, Bristol-Myers Squibb; consultant: Shering Plough, Sanofi-Aventis, Medicines, Heartscape; research funding: Schering Plough, Heartscape, Biosite. Many authors are also members of EMCREG-International, of which WBG is the president. EMCREG-International, a medical education company, provides non-biased, high-quality educational newsletters, monographs and symposia for emergency physicians and other healthcare providers providing emergency care. EMCREG-International has received unrestricted educational grants from Abbott POC/i-STAT, ArgiNOx, Biosite, Bristol-Myers Squibb, Heartscape Technologies, Inovise, The Medicines Company, Millennium Pharmaceuticals, PDL BioPharma, Roche Diagnostics, Sanofi-Aventis, Schering Plough and Scios (significant).
Funding: The i*trACS registry was supported by an unrestricted educational grant from Millenium Pharmaceuticals and Schering-Plough Pharmaceuticals.
The sponsors of the data registry had no role in the design and conduct of the study, collection, management, analysis, and interpretation of the data, or the preparation, review, and approval of the manuscript.