Background
Pathologic Q waves are the classic ECG sign of myocardial infarction. Prior studies have shown cardiac MRI is a more sensitive tool to detect myocardial necrosis. However, it is unclear whether pathologic Q waves on ECG always correlate with ischemic pattern of delayed enhancement. We tested the hypothesis that Q waves always indicate the presence of myocardial scaring on contrast enhanced cardiac Magnetic resonance imaging.
Methods
We included 41 (25% females) consecutive patients with pathologic Q waves on ECG who underwent contrast enhanced cardiac MRI (1.5 T) for various clinical reasons. Imaging protocols included cine SSFP sequence and post double dose contrast delayed imaging. Q waves were considered pathologic if the total Q wave voltage is more than one third of the QR voltage. Left ventricular myocardial scar was evaluated qualitatively using the AHA recommended 17 segment model by 2 readers who were blinded to the clinical and ECG data.
Results
A total of 29/41 (69%) patients had evidence of myocardial scar in coronary pattern, 18 (44%) of which were transmural. The presence of a Q only pattern (absence of R or S waves) did not improve the accuracy of ECG in identifying myocardial delayed enhancement on MRI. However, Q waves only modestly localized the scar. Anterior Q waves (64%) have the best correlation with the presence of scar in the anterior segments with lateral and inferior being 41% and 40% respectively. In addition, the Q only pattern did not improve the localizing accuracy of ECG.
Conclusion
The presence of pathologic Q waves on ECG is not always associated with the presence of prior myocardial infarction on cardiac MRI. In addition, Q waves appear to modestly correlate with the location of the prior MI. Further studies should evaluate the potential causes of pathologic Q waves in patients without prior myocardial infarction.
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Open Access This article is published under license to BioMed Central Ltd. This is an Open Access article is distributed under the terms of the Creative Commons Attribution 2.0 International License (https://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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Singh, G., Tzogias, L., Njeim, M. et al. Does the presence of Q waves on ECG indicate myocardial scar on cardiac MRI?. J Cardiovasc Magn Reson 11 (Suppl 1), P265 (2009). https://doi.org/10.1186/1532-429X-11-S1-P265
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DOI: https://doi.org/10.1186/1532-429X-11-S1-P265