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Q waves in ischemic cardiomyopathy.
Eduard Ródenas-Alesina1, Pablo Jordán2, Lorena Herrador2
1Cardiology Department, Hospital Universitari Vall D'Hebron, Institut de Recerca (VHIR), Universitat Autònoma de Barcelona, Passeig de la Vall d'Hebron, 08035, Barcelona, Spain. eduard.rodenas@gmail.com.
The International Journal of Cardiovascular Imaging
|January 31, 2021
Summary
In ischemic cardiomyopathy (ICM), Q waves can indicate scar tissue, not just non-viable tissue. These Q waves are linked to scar extent and location, particularly in apical segments.
Area of Science:
- Cardiology
- Nuclear Cardiology
- Cardiac Imaging
Background:
- Q waves on electrocardiograms (ECG) typically signify myocardial infarction and non-viable tissue.
- The presence and significance of Q waves in ischemic cardiomyopathy (ICM) without non-viable tissue require further investigation.
- Scintigraphic assessment of Q waves in ICM patients with preserved viability is not well-established.
Purpose of the Study:
- To determine the factors associated with Q waves in ICM patients lacking non-viable myocardial tissue.
- To evaluate the diagnostic accuracy of Q waves in identifying scar tissue in this specific population.
- To understand the relationship between Q waves, scar characteristics, and myocardial viability in ICM.
Main Methods:
- Retrospective analysis of 487 ICM patients with LVEF < 40% and narrow QRS.
- Utilized stress-rest 99mTc SPECT imaging with a 17-segment myocardial model.
- Defined non-viable tissue as severe perfusion defect without systolic thickening; scar viability assessed based on perfusion and thickening.
Main Results:
- Q waves were present in 65.7% of patients, correlating with more non-viable tissue and scar extent.
- Even after excluding non-viable segments, 51.9% of patients had Q waves, with 78.1% showing viable scar.
- Q waves were significantly associated with the extent (OR=1.19) and apical location (OR=1.88) of viable scar tissue.
Conclusions:
- Q waves in ICM patients poorly discriminate between viable and non-viable tissue.
- Extensive myocardial scars, even those meeting viability criteria, located in apical segments can manifest as Q waves.
- Q waves in ICM may represent transmural scar in viable myocardium, challenging traditional interpretations.
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