Background: Patients with ST elevation on electrocardiogram (ECG) require urgent and accurate diagnosis. Spodicks sign, a downsloping of the T-P segment, has been described as a sign of pericarditis, but it has not been validated. This study compares the frequency of Spodicks sign, and other findings, in patients diagnosed with ST elevation myocardial infarction (STEMI) with that in those diagnosed with pericarditis.
Methods: In this retrospective review, charts were selected meeting prospective definitions of STEMI and pericarditis, including negative testing for acute coronary syndrome for patients with pericarditis. Patients whose ECGs lacked ST elevation were excluded. ECGs were reviewed by an authority on electrocardiography (AM), who noted the presence or absence of Spodicks sign, ST depression (in leads other than V1 or aVR), PR depression, ST elevation in III > II, and upward ST convexity. Strength of association was quantified using odds ratios with 95% confidence intervals.
Results: Criteria for STEMI were met in 165 cases and in pericarditis for 42 cases. Spodicks sign was seen in 5% of patients with STEMI (95% CI, 3-10%) and in 29% of patients with pericarditis [95% CI 16-45%], with an odds ratio of 0.1 (95% CI 0.06-0.3). Other ECG findings had the following associations with STEMI: ST segment upward convexity, odds ratio 6 (95% CI 2-20); ST depression (in leads other than V1 or aVR), odds ratio 31 (95% CI 11-84); ST elevation in III>II, odds ratio 21 (95% CI 3-159); absence of PR depression, odds ratio 12 (95% CI, 6-27).
Conclusion: Spodicks sign is statistically associated with pericarditis, but it is still seen in 5% of STEMI. All other findings were useful in distinguishing STEMI from pericarditis, with ST depression (in leads other than V1 or aVR) having the strongest association with STEMI.