The endocardial extent of reperfused first-time myocardial infarction is more predictive of pathologic Q waves than is infarct transmurality: a magnetic resonance imaging study.
BACKGROUND
Historically, Q-wave myocardial infarction (MI) has been equated with transmural MI. This association have, however, recently been rejected. The endocardial extent of MI is another potential determinant of pathological Q waves, since the first part of the QRS complex where the Q wave appears reflects depolarization of subendocardial myocardium. Therefore, the aim of the present study was to test the hypothesis that endocardial extent of MI is more predictive of pathological Q waves than is MI transmurality and to investigate the relationship between QRS scoring of the ECG and MI characteristics.


METHODS
Twenty-nine patients with reperfused first-time MI were prospectively enrolled. One week after admission, delayed contrast-enhanced magnetic resonance imaging (DE-MRI) was performed and 12-lead ECG was recorded. Size, transmurality and endocardial extent of MI were assessed by DE-MRI. Q waves were identified with Minnesota coding and electrocardiographic MI size was estimated by QRS scoring of the ECG.


RESULTS
There was a significant difference between patients with and without Q waves with regard to MI size (P = 0.03) and endocardial extent of MI (P = 0.01), but not to mean and maximum MI transmurality (P = 0.09 and P = 0.14). Endocardial extent was the only independent predictor of pathological Q waves. Endocardial extent of MI was most strongly correlated to QRS score (r = 0.86, P<0.001) of the MI variables tested.


CONCLUSIONS
The endocardial extent of reperfused first-time acute MI is more predictive of pathological Q waves than is MI transmurality.
Engblom
Henrik
H
Department of Clinical Physiology, Lund University Hospital, Lund, Sweden. henrik.engblom@med.lu.se
Carlsson
Minna B
MB
Hedström
Erik
E
Heiberg
Einar
E
Ugander
Martin
M
Wagner
Galen S
GS
Arheden
Håkan
H
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D004562:Electrocardiography; D004699:Endocardium / Q000473:pathology* / Q000503:physiopathology; D005260:Female; D006329:Heart Conduction System / Q000503:physiopathology*; D006801:Humans; D016015:Logistic Models; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000175:diagnosis* / Q000473:pathology / Q000503:physiopathology / Q000601:surgery; D015425:Myocardial Reperfusion; D016017:Odds Ratio; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012107:Research Design