Limitations of premature ventricular complex morphology in the diagnosis of myocardial infarction.
To determine the diagnostic value of Q-waves (greater than or equal to 0.04 seconds duration) in premature ventricular complexes (PVC's) for the presence of myocardial scar, we examined 12-lead electrocardiograms and multiple lead rhythm strips obtained before and after exercise at the time of thallium-201 myocardial imaging in 970 patients. PVC's were found in 233 patients, 112 of whom had fixed thallium-201 perfusion defects indicative of myocardial scar. PVC's occurring during exercise were excluded from the analysis. Twenty-one patients had Q-wave PVC's in one or more electrocardiographic leads. Of those, 14 patients (67%) had myocardial scar in the suggested location. Myocardial scar was more common among patients with Q-wave PVC's than in patients without (67% vs. 36%, p less than 0.01). However, only 6 of 13 patients (46%) with Q-wave PVC's but no diagnostic sinus beats actually had myocardial scar. The remaining seven patients had Q-wave PVC's, no myocardial scar, and no evidence of myocardial ischemia suggested by angina during exercise, exercise electrocardiogram or thallium-201 imaging. We conclude that although Q-wave PVC's indicate the presence of myocardial scar in 67% of patients, they yield little or no additional diagnostic information to that obtained from the sinus beats
J M
JM
Wahl
A H
AH
Hakki
A S
AS
Iskandrian
B L
BL
Segal
D000328:Adult; D000368:Aged; D001145:Arrhythmias, Cardiac / Q000175:diagnosis; D002037:Bundle-Branch Block / Q000175:diagnosis; D005117:Cardiac Complexes, Premature / Q000175:diagnosis* / Q000503:physiopathology; D006332:Cardiomegaly / Q000175:diagnosis; D002921:Cicatrix / Q000175:diagnosis; D004562:Electrocardiography / Q000379:methods*; D005080:Exercise Test; D005260:Female; D006329:Heart Conduction System / Q000503:physiopathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000175:diagnosis* / Q000503:physiopathology; D011868:Radioisotopes; D013793:Thallium
D011868:Radioisotopes; D013793:Thallium