Assessing the Requirement for the 6-Hour Interval between Specimens in the American Heart Association Classification of Myocardial Infarction in Epidemiology and Clinical Research Studies

Abstract

Background:The American Heart Association (AHA) case definition for acute myocardial infarction (AMI) requires an "adequate set" of biomarkers: 2 measurements of the same marker at least 6 h apart. A sensitive troponin assay might detect significant changes in concentration earlier. We determined AMI prevalence, using protocols with shorter intervals between measurements, with and without incorporating the time from onset of symptoms. Methods: The AHA case definition was used to retrospectively assign a diagnosis in 258 patients presenting to the emergency department with symptoms of cardiac ischemia. AMI was diagnosed if either specimen in an adequate set had a cardiac troponin I (cTnI) above the 99th percentile (AccuTnI

Correlation between lipid profile and troponin I test results in patients with chest pain in Nepal

“…In a previous study of subjects with chest pain it was reported that troponin was positive in 79 subjects (18.4%) and negative in 351 (81.6%) subjects [4][5][6] . They also reported higher incidence of acute myocardial infarction, acute heart failure, and death due to cardiac event in the subjects with chest pain and positive troponin confirming that it is a powerful, independent and valuable tool for risk stratification in patients with acute chest pain.…”

Health Outcomes Categorized by Current and Previous Definitions of Acute Myocardial Infarction in an Unselected Cohort of Troponin-Naïve Emergency Department Patients

“…The study population and its characteristics have been reported previously (8,9 ). Briefly, the study cohort consisted of 448 unique patients who were enrolled in 1996 as part of an emergency department cardiac marker study at Oshawa General Hospital (now Lakeridge Health Oshawa).…”

“…Briefly, the study cohort consisted of 448 unique patients who were enrolled in 1996 as part of an emergency department cardiac marker study at Oshawa General Hospital (now Lakeridge Health Oshawa). The study included all patients presenting with symptoms suggestive of cardiac ischemia as assessed by triage staff (8,9 ). The leftover plasma specimens from 1996 were frozen at Ϫ70°C, with the exception of brief periods when they were at Ϫ20°C.…”

“…The leftover plasma specimens from 1996 were frozen at Ϫ70°C, with the exception of brief periods when they were at Ϫ20°C. In 2003, the specimens were thawed and analyzed for cardiac troponin I (cTnI) by the AccuTnI assay (Beckman Coulter Inc.) without knowledge of the previous clinical diagnoses (8,9 ). Specimen stability with the AccuTnI troponin assay after multiple freeze-thaw cycles has been well documented (10,11 ).…”

“…For the retrospective ESC/ACC diagnosis, we evaluated the peak cTnI concentration in each patient against 2 cutoffs: the 99th percentile (0.04 g/L) and 10% CV (0.06 g/L). Concentrations exceeding the cutoff were classified as AMI positive (8,9,12 ). For 24% of our population (n ϭ 108) only 1 specimen, collected at presentation, was available, and the measured cTnI of this specimen was considered the peak concentration.…”