Diagnosis of myocardial infarction-induced ventricular aneurysm in the presence of complete left bundle branch block

On the nonpathological nature of ST-segment elevation in lateral leads in patients with CRBBB

Stable ST-segment elevation (STSE) in the lateral electrocardiogram (ECG) leads (i.e., I, II, aVL, V5, and V6) are frequently encountered in association with stable and transient complete right bundle branch block (CRBBB). These STSE in the lateral ECG leads in patients with CRBBB, represent parallel changes to the ST-segment depression seen in the V1-V3 leads, and both represent secondary ECG changes expected in patients with intraventricular conduction delays, and they are opposite in polarity to the latter part of the QRS complexes. Proprietary automated ECG interpretation algorithms provided by the different electrocardiographs associate such ECG changes in the lateral leads in the presence of CBBB to "lateral myocardial infarction, ischemia, or injury," "pericarditis," or "early repolarization," which results in inappropriate concern among clinicians, and leads to costly unnecessary diagnostic testing. This piece strives to reassure clinicians about the nonpathological nature of lateral STSE in ECGs with CRBBB.

Diagnosis of ventricular aneurysm and other severe segmental left ventricular dysfunction consequent to a myocardial infarction in the presence of right bundle branch block: ECG correlates of a positive diagnosis made via echocardiography and/or contrast ventriculography

BACKGROUND

A diagnostic ECG sign of a ventricular aneurysm (VA) consequent to a myocardial infarction (MI) in the presence of complete left bundle branch block was recently described, and consists of the presence of ST-segment elevation (+ST), instead of the expected ST-segment depression (-ST), in leads V4-6. Generally, complete right bundle branch block (RBBB) is associated with -ST in ECG leads V1-3. We hypothesized that stable +ST, instead of the expected -ST in leads V1-3 in patients with RBBB could be also diagnostic of a VA and other severe segmental left ventricular dysfunction (VA/SSD). Thus, this study was performed to explore the feasibility of using the ECG to diagnose a VA/SSD in the presence of RBBB, and to evaluate the determinants of such diagnosis.

METHODS

The frequency of +ST > or =1 mm in leads V1-3 was assessed in patients with RBBB, prior MI, and a VA/SSD diagnosed by echocardiography and/or contrast left cine-ventriculography. The ECG correlates for a positive or negative diagnosis of a VA/SSD were explored.

RESULTS

Out of 4197 files of our cohort of the Cardiology Clinic, RBBB was detected in 175 patients. Of these, 28 had an old MI, and had a VA/SSD diagnosed by > or =1 of noninvasive and/or invasive non-ECG tests. Twenty-one of these 28 patients had stable +ST in > or =1 of leads V1-3 (Group 1), and 7 did not (Group 2). Thus, the sensitivity of this ECG criterion for the diagnosis of VA/SSD was 75%, and the specificity was 100% in this highly selective group. VA/SSD in the septal and anterior myocardial regions was more frequent in the patients of Group 1, than in the patients of Group 2 (P = 0.03 and 0.02, correspondingly). The number of myocardial territories involved with the VA/SSD, or the ejection fraction were not different in the two groups (P = 0.65 and 0.55, correspondingly).

CONCLUSION

VA/SSD can be diagnosed in the presence of RBBB by the concordant to the QRS repolarization changes (+ST) in leads V1-3. Positivity of this ECG marker for VA/SSD correlates with involvement of the septal or anterior myocardial regions, and represents mechanistically a superimposition of primary repolarization alterations, overcoming the secondary such changes.