Can the surface electrocardiogram be used to predict myocardial viability?

Area of Science:

• Cardiology
• Medical Imaging
• Electrophysiology

Background:

• Myocardial viability assessment is crucial for guiding revascularization decisions in patients with left ventricular impairment.
• Surface electrocardiogram (ECG) patterns may offer non-invasive insights into myocardial scar and hibernation.
• Distinguishing between scarred and viable (hibernating) myocardium is essential for effective treatment planning.

Purpose of the Study:

• To determine if QRS morphology on surface ECG can predict myocardial viability.
• To investigate the relationship between pathological Q waves and myocardial scarring.
• To assess the significance of QR and QS complexes in predicting hibernating myocardium.

Main Methods:

• 58 patients with left ventricular impairment underwent ECG and positron emission tomography (PET) using (13)N-Ammonia (perfusion) and (18)F-fluorodeoxyglucose (metabolism).
• Matched defects (reduced uptake of both markers) indicated scarred myocardium.
• Mismatched defects (reduced perfusion with preserved metabolism) indicated hibernating myocardium.

Main Results:

• Q waves were specific (79%) but not sensitive (41%) for matched defects, with 77% positive predictive accuracy.
• The size of matched defects associated with Q waves (20% LV) was not significantly different from those without Q waves (18%).
• The incidence of mismatched defects was similar for QR (19%) and QS (30%) patterns within Q-wave regions.

Conclusions:

• Q waves are specific but not sensitive markers for scarred myocardium (matched defects).
• Q waves followed by R waves (QR pattern) are not more indicative of hibernating myocardium than QS complexes.