Clinical significance of 12-lead electrocardiogram QRS scores on admission in ST-segment elevation myocardial infarction

Abstract Background A QRS scoring system by 12-lead electrocardiography (ECG) is a quick and simple method to evaluate degree and extension of myocardial infarction. Previous studies have shown that high QRS scores (≥5) at hospitalization (before reperfusion) related to impaired myocardial reperfusion during percutaneous coronary intervention (PCI) and subsequent poor prognosis in patients with ST-segment elevation myocardial infarction (STEMI) (Figure 1). However, the pathogenesis and associated factors with high QRS scores remain poorly defined. Therefore, this study aimed to explore clinical and lesion characteristics associated with QRS scores at hospitalization in patients with STEMI. Methods This retrospective observational study enrolled 138 broad anterior-wall STEMI patients who underwent PCI in the proximal left anterior descending artery and achieved reperfusion within 3 hours of onset. Patients were divided by QRS scores at hospitalization into low (<5: n=97) and high (≥5: n=41) QRS-scores, and clinical and lesion characteristics were compared between the 2 groups. Lesion characteristics were evaluated by intravascular ultrasound (IVUS). Results Despite early phase of STEMI, QRS scores at hospitalization varied (3 [2-5] points). Clinical characteristics, including onset-to-door time (66 [41-101] min vs. 55 [42-76] min) and onset-to-reperfusion time (112 [88-145] min vs. 106 [81-120] min), were comparable between patients with low and high QRS-scores. In contrast, significantly higher percentages of lipid plaques, plaque rupture and large thrombus were seen at the culprit lesion sites in patients with high versus low QRS scores (Figure 2). As a result, patients with high QRS scores had higher incidence of no-reflow phenomenon during PCI (36.6% vs. 12.6%, p<0.05) and larger infarct size assessed by peak CK values (5333 [3307-7443] IU/l vs. 1941 [759-3559], p<0.05) compared with those with low QRS-scores. Conclusions High QRS scores at hospitalization were associated with vulnerable lesion characteristics, as well as impaired coronary reperfusion and large infarct size. Although the exact mechanisms of the associations require future studies, QRS scores may help risk stratification before reperfusion and prognostic prediction after reperfusion.Figure 1.Figure 2.