Background: Patients with ST elevation on electrocardiogram (ECG) could have ST elevation myocardial infarction (STEMI) or pericarditis. Spodick's sign, a downsloping of the ECG baseline (the T-P segment), has been described, but not validated, as a sign of pericarditis.
Objective: This study estimates the frequency of Spodick's sign and other findings in patients diagnosed with STEMI and those with pericarditis.
Methods: In this retrospective review, we selected charts that met prospective definitions of STEMI (cases) and pericarditis (controls). We excluded patients whose ECGs lacked ST elevation. An authority on electrocardiography reviewed all ECGs, noting the presence or absence of Spodick's sign, ST depression (in leads besides V1 and aVR), PR depression, greater ST elevation in lead III than in lead II (III > II), abrupt take-off of ST segment (the RT checkmark sign), and upward or horizontal ST convexity. We quantified strength of association using odds ratio (OR) with 95% confidence interval (CI).
Results: One hundred and sixty-five patients met criteria for STEMI and 42 met those for pericarditis. Spodick's sign occurred in 5% of patients with STEMI (95% CI 3-10%) and 29% of patients with pericarditis (95% CI 16-45%). All other findings statistically distinguished STEMI from pericarditis, but ST depression (OR 31), III > II (OR 21), and absence of PR depression (OR 12) had the greatest OR values.
Conclusions: Spodick's sign is statistically associated with pericarditis, but it is seen in 5% of patients with STEMI. Among other findings, ST depression, III > II, and absence of PR depression were the most discriminating.
Keywords: ST elevation myocardial infarction; chest pain; electrocardiography; emergency service; hospital; pericarditis.
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