Left main coronary artery lesion detected by transoesophageal echocardiography before cardioversion

Objective-To investigate whether QRS morphology on the surface ECG can be used to predict myocardial viability.Design-ECGs of 58 patients with left ventricular impairment undergoing positron emission tomography (PET) were studied. 13N-Ammonia (NH 3 ) and 18 Ffluorodeoxyglucose (FDG) were the perfusion and the metabolic markers, respectively.The myocardium is scarred when the uptake of both markers is reduced (matched defect).Reduced NH 3 uptake with persistent FDG uptake (mismatched defect) represents hibernating myocardium.First, the relation between pathological Q waves and myocardial scarring was investigated.Second, the significance of QR and QS complexes in predicting hibernating myocardium was determined.Results-As a marker of matched PET defects, Q waves were specific (79%) but not sensitive (41%), with a 77% positive predictive accuracy and a poor (43%) negative predictive accuracy.The mean size of the matched PET defect associated with Q waves was 20% of the left ventricle.This was not significantly diVerent from the size of the matched PET defects associated with no Q waves (18%).Among the regions associated with Q waves on the ECG, there were 16 regions with QR pattern (group A) and 23 regions with QS pattern (group B).The incidence of mismatched PET defects was 19% of group A and 30% of group B (NS).Conclusions-Q waves are specific but not sensitive markers of matched defects representing scarred myocardium.Q waves followed by R waves are not more likely to be associated with hibernating myocardium than QS complexes.