The relationship between terminal QRS distortion on initial ECG and final infarct size at 4months in conventional ST- segment elevation myocardial infarct patients

Abstract

Background: In the Sclarovsky-Birnbaum Ischemia Severity Grading System for patients with ST-segment elevation myocardial infarction (STEMI), "Terminal QRS distortion" is considered as "Grade III". This evidence for most severe ischemia is associated with cardiovascular magnetic resonance imaging (CMR) markers of myocardial damage in the subacute phase. Our aim was to assess whether terminal QRS distortions on the initial electrocardiogram (ECG) is predictive for infarct size (IS) and left ventricular ejection fraction (LVEF) at 4months in anterior versus infarct locations.

Methods: Patient data of the HEBE, GIPS III and MAST, were pooled. ECGs of 411 STEMI patients were classified as absence (Grade II) or presence (Grade III) of terminal QRS distortion according to Sclarovsky-Birnbaum grading. CMR was performed at approximately 4months and included IS and LVEF.

Results: Grade III ischemia was present in 142 of 411 (35%) patients and was more frequently observed with inferior STEMI (P=0.01). In the total cohort and in anterior STEMI, no difference in LVEF or IS was observed between the two Grades. Whereas, in inferior STEMI Grade III was associated with a larger IS (P<0.01) and also, a trend towards a lower LVEF was observed (P=0.09).

Conclusion: In inferior STEMI, terminal QRS distortion on the initial ECG is associated with a larger IS at approximately 4months, and can be used to identify a high-risk population in the acute phase. Also, a Grade III was associated with a trend towards a lower LVEF.

Keywords: Electrocardiography; Magnetic resonance imaging; Myocardial infarction; QRS distortion.