Comparison of serial measurements of infarct size and left ventricular ejection fraction by contrast-enhanced cardiac magnetic resonance imaging and electrocardiographic QRS scoring in reperfused anterior ST-elevation myocardial infarction.
BACKGROUND
Left ventricular ejection fraction (LVEF) is a powerful prognostic marker after acute myocardial infarction and is dependent on infarct magnitude. Contrast-enhanced cardiac magnetic resonance (ceCMR) represents the current criterion standard means of LVEF and infarct size measurement. Infarct size and LVEF can be estimated from the 12-lead electrocardiogram (ECG) using the Selvester QRS score. We examined for the first time the relationship between serial measures of LVEF and infarct size by ceCMR and ECG in patients with reperfused anterior ST-elevation myocardial infarction (STEMI) and depressed LVEF.


METHODS
Thirty-four patients (mean +/- SD age, 59 +/- 11.8 years; 70.6% male) underwent ceCMR and simultaneous ECG at mean 93 hours after admission and at 12 and 24 weeks. The QRS score was calculated on each ECG, from which infarct size and LVEF were estimated and compared with the equivalent ceCMR measurements.


RESULTS
Infarct size on ceCMR was higher than that by QRS score at each time-point (P < .001) with modest correlation (r = 0.56-0.78, P < .001). Left ventricular ejection fraction was consistently significantly higher on CMR than on ECG, with weak correlation (r = 0.37-0.51, P < .05). We derived a novel equation relating QRS score to CMR-measured LVEF in the subacute phase of infarction: LVEF = 61 - (1.7 x QRS score) (%).


CONCLUSIONS
In patients with reperfused anterior ST-elevation myocardial infarction and depressed LVEF, ceCMR is moderately correlated with the QRS in the serial measurement of infarct size and LVEF. Infarct size (measured by ceCMR) and LVEF are consistently higher than those calculated on the QRS score in the acute and subacute phases of infarction.
Weir
Robin A P
RA
Cardiology Department, Western Infirmary, Glasgow, Scotland, UK. robinweir75@hotmail.com
Martin
Thomas N
TN
Murphy
Charles Aengus
CA
Petrie
Colin J
CJ
Clements
Suzanne
S
Steedman
Tracey
T
Dargie
Henry J
HJ
Wagner
Galen S
GS
D003287:Contrast Media; D004562:Electrocardiography / Q000379:methods*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000150:complications / Q000175:diagnosis* / Q000628:therapy*; D015425:Myocardial Reperfusion; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013318:Stroke Volume; D016896:Treatment Outcome; D018487:Ventricular Dysfunction, Left / Q000175:diagnosis* / Q000209:etiology / Q000517:prevention & control*
D003287:Contrast Media