Electrocardiographic Q-wave "remodeling" in reperfused ST-segment elevation myocardial infarction: validation study with CMR.
OBJECTIVE
The aim of this study was to evaluate the evolution in Q-wave expression during the first 5 years after a primary, successfully reperfused ST-segment elevation myocardial infarction (MI), using cardiac magnetic resonance (CMR) for infarct location, and to depict changes in infarct size and left ventricular remodeling over time.


BACKGROUND
In the absence of QRS confounders, abnormal Q waves are usually diagnostic of myocardial necrosis. It is hypothesized that Q-wave regression after MI could be related to smaller infarct sizes. Late gadolinium enhancement accurately depicts MI of any age.


METHODS
Forty-six MI patients underwent electrocardiography and CMR at 1 week (baseline), 4 months, 1 year, and 5 years post-infarction. Conventional CMR parameters were analyzed, and infarct presence, location, and size were assessed using late gadolinium enhancement CMR. Infarct locations were anterior or nonanterior (inferior and/or lateral), using late gadolinium enhancement CMR as a reference. For each time point, patients were classified as having a diagnostic/nondiagnostic electrocardiogram (ECG) using the European Society of Cardiology/American College of Cardiology Foundation/American Heart Association/World Heart Federation consensus criteria for previous Q-wave infarct.


RESULTS
At baseline, 11 patients (23%) did not meet the criteria for Q-wave MI. Non-Q-wave infarcts were significantly smaller than Q-wave infarcts (p < 0.0001). All anterior Q-wave infarcts (n = 17) were correctly localized, whereas in 7 of 19 nonanterior Q-wave infarcts, the location or extent of the infarct was misjudged by electrocardiography. At 4-month/1-year follow-up, in 10 patients (3 anterior/7 nonanterior), the ECG became nondiagnostic. The ECG remained nondiagnostic at 5-year follow-up. A cutoff infarct size of 6.2% at 1 year yielded a sensitivity of 89% and a specificity of 74% to predict the presence or absence of Q waves.


CONCLUSIONS
The incidence of nondiagnostic ECGs for previous MI using the current European Society of Cardiology/American College of Cardiology Foundation/American Heart Association/World Heart Federation criteria is substantial and increases with time post-infarction from 23% immediately post-infarction to 44% at 5-year follow-up.
Department of Radiology, UZ Leuven, Leuven, Belgium.
Anca
A
Florian
Massimo
M
Slavich
Pier Giorgio
PG
Masci
Stefan
S
Janssens
Jan
J
Bogaert
D000328:Adult; D000368:Aged; D000704:Analysis of Variance; D056988:Anterior Wall Myocardial Infarction / Q000175:diagnosis* / Q000473:pathology / Q000503:physiopathology / Q000628:therapy*; D016009:Chi-Square Distribution; D003287:Contrast Media; D004562:Electrocardiography; D005060:Europe; D005260:Female; D006329:Heart Conduction System / Q000503:physiopathology*; D006801:Humans; D056989:Inferior Wall Myocardial Infarction / Q000175:diagnosis* / Q000473:pathology / Q000503:physiopathology / Q000628:therapy*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009206:Myocardium / Q000473:pathology*; D062645:Percutaneous Coronary Intervention; D011237:Predictive Value of Tests; D012372:ROC Curve; D016032:Randomized Controlled Trials as Topic; D015203:Reproducibility of Results; D012189:Retrospective Studies; D033581:Stem Cell Transplantation; D013997:Time Factors; D016896:Treatment Outcome; D020257:Ventricular Remodeling
D003287:Contrast Media