Prognostic significance of the distortion of terminal portion of QRS complex on admission electrocardiogram in ST segment elevation myocardial infarction

Abstract

Background: ECG on admission has been used in predicting prognosis and risk stratification in ST segment elevation acute myocardial infarction (STEMI).

Objective: To analyze the admission ECG in STEMI based on abnormality observed in terminal portion of QRS and its correlation to hospital mortality.

Method: 160 consecutive patients of STEMI were classified into subjects without (Group I) and with distortion of terminal QRS (Group II), Pattern A--Emergence of J point at ≥50% of the R wave amplitude in leads with qR configuration or Pattern B--Absence of the S waves, in leads with Rs configuration in two consecutive leads.

Results: Out of 160 patients of STEMI, 69 (43.1%) had distortion of QRS. There were 13 deaths (8.1%). Hospital mortality was found to be significantly more in subjects with distortion than those without (15.9% V/S 2.1%, p < 0.001). Patients with QRS distortion tended to have larger infarction as assessed by Killip class on admission (p < 0.05), anterior location of MI (p < 0.01) and presence of significant Q waves in leads with ST segment elevation (p < 0.0001). With multiple logistic regression analysis using hospital mortality as a dependent variable and all studied risk factors as independent variables, QRS distortion on admission ECG was the only variable found to be statistically significant (Adjusted OR = 7.161, p < 0.05).

Conclusion: ECG on admission is a simple, cheap, universally available investigation that can predict the short term prognosis in STEMI and would help in deciding which patients should go for other myocardial revascularization procedures.

Keywords: AMI; ECG changes; Prognosis.

Fig. 1

Group I: No QRS distortion. J point emerges below 50% of the R wave amplitude. Group II: Terminal QRS distortion. Pattern A – emergence of J point ≥50% of the R wave amplitude in lead with qR configuration or Pattern B – absence of the S wave in lead with Rs configuration.

Fig. 2

Admission electrocardiograms of 2 patients with anterior wall AMI. (I) is an example of Group I – i.e. without QRS distortion. Despite having a high degree of ST elevation, the S waves in leads V₁, V2, V₃ are preserved and the J points emerge at <50% of the R wave amplitude in leads V₄, V5, and V6 (II) is an example of Group II – i.e. with QRS distortion. Despite having a high degree of ST elevation, the S waves in leads V₁, V₂, V₃, V₄ and V₅ are absent and the J points in leads V₂, V₃, and V₄ emerge at ≥50% of the R wave amplitude.

Fig. 3

Admission electrocardiograms of 2 patients with inferior wall AMI (1) is an example of Group I – i.e. without QRS distortion. J points emerge at <50% of the R wave amplitude in leads II and avF (II) is an example of Group II – i.e. with QRS distortion. J points emerge at ≥50% of the R wave amplitude in leads III and avF.