Thursday, May 31, 2007

Electrocardiographic findings in pulmonary embolism and acute coronary syndrome

Due to overlapping clinical presentations acute coronary syndrome (ACS) and pulmonary embolism (PE) can be confused. Moreover, both can be associated with electrocardiographic manifestations (T wave abnormality), elevated troponin levels (present in 42% of patients with PE in this study), and elevated d-dimer levels.

This case report (free full text after registration) illustrates disastrous consequences of massive PE mistaken for ACS. The electrocardiogram shown in the case report displayed findings which could be attributed to either ACS or PE. And while the tracing had a few previously described “red flags” for PE the elecrocardiographic distinction between ACS and PE had not been systematically studied as far as I am aware.

That’s why this paper from the March 15 issue of the American Journal of Cardiology is important. The authors studied patients with either ACS or PE who had T wave inversion on consecutive precordial leads. Among the findings: “In patients with APE, negative T waves were commonly present in leads II, III, aVF, V1, and V2, but were less frequent in leads I, aVL, and V3 to V6” and “Negative T waves in leads III and V1 were observed in only 1% of patients with ACS compared with 88% of patients with APE”. The sensitivity for PE in patients showing negative T waves in both III and V1 must be interpreted with caution, since the study population consisted only of patients with precordial lead T wave inversion. The sensitivity of the finding among PE patients in general is low. A normal electrocardiogram does not rule out PE. Nevertheless the findings of this paper should prove useful in distinguishing between ACS and PE in patients who have precordial T wave abnormality.

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