Objectives ST elevation myocardial infarctions (STEMIs) and non-ST elevation myocardial infarctions (NSTEMIs) have differences that can be important to differentiate. Our primary hypothesis was that corrected QT (QTc) duration and… Click to show full abstract
Objectives ST elevation myocardial infarctions (STEMIs) and non-ST elevation myocardial infarctions (NSTEMIs) have differences that can be important to differentiate. Our primary hypothesis was that corrected QT (QTc) duration and troponin I levels were higher in STEMIs compared with NSTEMIs. The objective of our study was to compare STEMIs with NSTEMIs for QTc duration and troponin levels. Methods This was a retrospective case–control study of all STEMIs and a random sample of NSTEMIs during a 1-year period. STEMIs were retrieved by searching our electrocardiogram database for all of the cardiology-diagnosed STEMIs. NSTEMIs were found by selecting a randomized sample of all of the patients with a final discharge diagnosis of NSTEMI. Records and electrocardiograms were reviewed for initial troponin I levels and QTc duration. Data extractors were educated formally and a 5% sample was reevaluated by the other extractor as a reliability measure. Data analysis included &khgr;2 tests and parametric or nonparametric analysis, where appropriate. A logistic regression model was created with variables selected a priori for predictors of STEMIs compared with NSTEMIs. Results A total of 92 STEMIs and 111 NSTEMIs were evaluated, and interrater reliability showed 90% agreement. Patients with NSTEMIs had significantly longer QTc. Troponin I did not differ on univariate analysis. In a logistic model, Hispanics were more likely than whites to have a STEMI (adjusted odds ratio [AOR] 2.2, 95% confidence interval [CI] 1.09–4.5). An increase in troponin I of 1 was associated with a 7% increase in the AOR of a STEMI (AOR 1.7, 95% CI 1.03–1.12) and an increase in QTc by 10 was associated with a 13% decrease in the AOR of a STEMI (AOR 0.87, 95% CI 0.78–0.93). Conclusions Patients with NSTEMIs had longer QTc intervals and lower troponin I levels than those with STEMIs.
               
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