Clinical Implications of Electrocardiograms for Patients With Non-ST-Segment Elevation Acute Coronary Syndromes in the Interventional Era

Abstract

Circ J 2009; 73: 798 -805 atients with non-ST-segment elevation acute coronary syndromes (NSTE-ACS) are heterogeneous with regard to both the underlying pathophysiology and the future risk of cardiac events. 1 Early risk stratification is crucial for appropriate management of this condition and for deciding whether early invasive strategies should be adopted. 2 Because of its simplicity, safety, widespread availability and low cost, the electrocardiogram (ECG) has been extensively used for risk stratification. The ECG plays a central role in diagnostic and triage pathways for NSTE-ACS and provides important prognostic information in the current interventional era. Importance of ECG in Risk StratificationTwo treatment strategies have emerged for the early management of NSTE-ACS: one strategy is invasive, and the other is conservative. General consensus has been reached that patients at higher risk benefit more from early invasive strategies, increasing the importance of appropriate risk stratification. Recently, biomarkers of myocardial damage (troponin), inflammation (C-reactive protein), hemodynamic stress (brain natriuretic peptide, N-terminal pro-brain natriuretic peptide) and renal function (creatinine) have also been linked to the risk of subsequent cardiac events. [3][4][5] However, the GUSTO-IV (Global Utilization of Strategies to Open Occluded Arteries-IV ACS) trial of 7,800 patients with NSTE-ACS has highlighted the striking prognostic value of ST-segment depression on admission as compared with independent factors, including expanded biomarker profiles as well as traditional risk factors (Figure 1). 3 The ECG thus continues to have important roles in prognosis as well as in diagnosis and selection of the optimal treatment strategy in patients with NSTE-ACS. ST-Segment DepressionST-segment changes are considered the most important electrocardiographic feature during acute myocardial ischemia. In patients with transmural ischemia, ST-segment elevation is present in leads facing the site of ischemia. Therefore, the ischemia-related artery can be predicted on the basis of the leads showing ST-segment elevation during ischemic attacks. Whereas in many patients with non-transmural ischemia, ST-segment depression occurs in leads V4 to V6 leads (mainly in lead V5) independently of the ischemiarelated artery, in which underlying mechanism remains unclear. It is thus difficult to predict the ischemia-related artery on the basis of these leads. On exercise thallium myocardial scintigraphy, however, the site of a reversible decrease in blood flow corresponds to the region supplied by the ischemia-related artery, even in patients who have ST-segment depression in leads V4 to V6 (primarily lead V5) during myocardial ischemia.The presence of acute ischemic changes on the admission ECG has been associated with a higher risk of cardiac events; ST-segment depression is an especially strong predictor of poor outcomes in patients with NSTE-ACS. 3,[6][7][8][9][10][11][12][13][14][15] The presence of even minimal (0.05 ...

Clinical Implications of Electrocardiograms for Patients With Anterior Wall ST-Segment Elevation Acute Myocardial Infarction in the Interventional Era

“…46 In this review, we discussed various pathological characteristics of anterior wall STEMI on the basis of the ECG findings. We hope this will contribute to the optimal use of these findings in clinical practice, taking into account inherent limitations of the technique.…”

Comparative clinical implications of admission electrocardiographic findings for patients with non-ST-segment elevation myocardial infarction

“…Previous studies have also shown similar baseline and clinical characteristics in the ST-segment depression group. [4,5] In particular, these comorbidities in the ST-depression group and the no ECG change group were more distinct than those seen in previous studies, [4,5] which may suggest that our study population is a real-world practice, including more high-risk patients than other randomized studies. However, some studies [6,7] reported that hospital mortality increased as the number of cardiovascular risk factors declined.…”

Early, Accurate, Non-Invasive Predictors of Left Main or 3-Vessel Disease in Patients With Non-ST-Segment Elevation Acute Coronary Syndrome

“…29,30 A standard 12-lead ECG on admission is the initial and most widely used method for early risk stratification in patients with NSTE-ACS. 31 Our study showed that QRS prolongation and ST-segment elevation in lead aVR on admission (especially the former) are useful for predicting LM/3VD and can thereby facilitate decision-making, that is, patients likely to have LM/3VD should promptly undergo an angiography and not receive clopidogrel therapy to allow early CABG. Our results emphasize the importance of analyzing QRS duration as well as ST-segment deviation on the admission ECG in the diagnostic workup of patients with NSTE-ACS.…”