Electrocardiographic criteria for predicting total occlusion of the proximal left anterior descending coronary artery in anterior wall acute myocardial infarction

A new 4-variable formula to differentiate normal variant ST segment elevation in V2-V4 (early repolarization) from subtle left anterior descending coronary occlusion - Adding QRS amplitude of V2 improves the model

INTRODUCTION

Precordial normal variant ST elevation (NV-STE), previously often called "early repolarization," may be difficult to differentiate from subtle ischemic STE due to left anterior descending (LAD) occlusion. We previously derived and validated a logistic regression formula that was far superior to STE alone for differentiating the two entities on the ECG. The tool uses R-wave amplitude in lead V4 (RAV4), ST elevation at 60 ms after the J-point in lead V3 (STE60V3) and the computerized Bazett-corrected QT interval (QTc-B). The 3-variable formula is: 1.196 x STE60V3 + 0.059 × QTc-B - 0.326 × RAV4 with a value ≥23.4 likely to be acute myocardial infarction (AMI).

HYPOTHESIS

Adding QRS voltage in V2 (QRSV2) would improve the accuracy of the formula.

METHODS

355 consecutive cases of proven LAD occlusion were reviewed, and those that were obvious ST elevation myocardial infarction were excluded. Exclusion was based on one straight or convex ST segment in V2-V6, 1 millimeter of summed inferior ST depression, any anterior ST depression, Q-waves, "terminal QRS distortion," or any ST elevation >5 mm. The NV-STE group comprised emergency department patients with chest pain who ruled out for AMI by serial troponins, had a cardiologist ECG read of "NV-STE," and had at least 1 mm of STE in V2 and V3. R-wave amplitude in lead V4 (RAV4), ST elevation at 60 ms after the J-point in lead V3 (STE60V3) and the computerized Bazett-corrected QT interval (QTc-B) had previously been measured in all ECGs; physicians blinded to outcome then measured QRSV2 in all ECGs. A 4-variable formula was derived to more accurately classify LAD occlusion vs. NV-STE and optimize area under the curve (AUC) and compared with the previous 3-variable formula.

RESULTS

There were 143 subtle LAD occlusions and 171 NV-STE. A low QRSV2 added diagnostic utility. The derived 4-variable formula is: 0.052*QTc-B - 0.151*QRSV2 - 0.268*RV4 + 1.062*STE60V3. The 3-variable formula had an AUC of 0.9538 vs. 0.9686 for the 4-variable formula (p = 0.0092). At the same specificity as the 3-variable formula [90.6%, at which cutpoint (≥23.4), 123 of 143 MI were correctly classified for 86% sensitivity], the sensitivity of the new formula at cutpoint ≥17.75 is 90.2%, with 129/143 correctly classified MI, identifying an additional 6 cases. The cutpoint with the highest accuracy (92.0%) was at a cutoff value ≥18.2, with 88.8% sensitivity, 94.7% specificity, and a positive and negative likelihood ratio of 16.9 (95% CI: 8.9-32) and 0.12 (95% CI: 0.07-0.19). At this cutpoint, it correctly classified an additional 11 cases (289 of 315, vs. 278 of 315): 127/143 for MI (an additional 4 cases) and 162/171 for NV-STE (an additional 7 cases).

CONCLUSION

On the ECG, a 4-variable formula was derived which adds QRSV2; it differentiates subtle LAD occlusion from NV-STE better than the 3-variable formula. At a value ≥18.2, the formula (0.052*QTc-B - 0.151*QRSV2 - 0.268*RV4 + 1.062*STE60V3) was very accurate, sensitive, and specific, with excellent positive and negative likelihood ratios. This formula needs to be validated.

Electrocardiographic predictors of proximal left anterior descending coronary artery occlusion

Proximal occlusion of the left anterior descending coronary artery (LAD) results in a less favorable prognosis in coronary angiography. Therefore, it is important to determine whether there are significant lesions in LAD by electrocardiography (ECG) before coronary angiography. Twelve-lead ECG was compared in 130 patients with significant lesions (≥70% stenosis) confined to proximal part of the LAD (P LAD group) and 492 patients with normal coronary angiography (control group). Fifty-nine patients in the P LAD group and 18 patients in the control group had signs of anterior myocardial infarction as shown by ST elevation (≥1.0 mV) in two consecutive pericardial leads or the presence of a pathological Q wave. An inverted U wave (biphasic T wave) in leads V1 to V4 had a sensitivity of 49.3% (35/71) in P LAD patients without signs of anterior myocardial infarction (MI) and 96.6 % (57/59; specificity, 66.6%; positive predictive value, 90.9 %) in the P LAD patients with signs of anterior MI. In the P LAD patients with signs of anterior MI, T inversion in V4–V5 had a lower sensitivity (67.0% [40/59]) than an inverted U wave. ST depression in inferior leads and ST depression in V5 were not useful markers of proximal LAD occlusion. In conclusions, an inverted U wave in V1 to V4 (or in each of these leads) and T inversion in V4–V5 are the best predictors of significant proximal LAD lesion, especially in patients with ECG findings of anterior MI.

Detection of proximal coronary occlusion in acute coronary syndrome: a feasibility study using computerized electrocardiographic analysis

BACKGROUND

Rapid identification of a proximal occlusion site of a major coronary artery is of paramount importance in the care of myocardial infarction (MI). It is increasingly recognized that routine electrocardiogram (ECG) can be used for that purpose, provided that expert interpretation is available. Computer-based signal analysis has potential to enhance early ECG interpretation but its performance must be validated against manual algorithms. We therefore set out to develop a computer-assisted model to detect proximal occlusion of the left anterior descending coronary artery (LAD) in patients with suspected acute coronary syndrome (ACS).

METHODS

Based on manual anatomical interpretation of the ECG, obtained from 216 consecutive patients who were admitted due to suspected ACS, an automatic computerized ECG model to detect LAD occlusion was constructed. Agreement between manual evaluation of the ECG by two cardiologists and a computerized ECG algorithm to detect occlusion of the LAD and the site of occlusion was determined.

RESULTS

Using an expert electrocardiographer's anatomical interpretation as the gold standard, the computer model recognized patients fulfilling ECG criteria for any occlusion of the LAD with a specificity of 99% and a sensitivity of 67% (kappa= 0.71). However, proximal LAD occlusion was detected with 100% specificity and 86% sensitivity (kappa= 0.72). The computer program detected a distal occlusion in the LAD with a specificity of 99% and a sensitivity of 40% (kappa= 0.72).

CONCLUSIONS

Computerized anatomical interpretation of the ECG is feasible and allows detection of a proximal LAD occlusion with excellent accuracy.

Acute coronary syndromes

Despite technologic advances in many diagnostic fields, the 12-lead ECG remains the basis for early identification and management of an acute coronary syndrome. This article reviews the use of the ECG in acute coronary syndromes.

Differentiation between patients with takotsubo cardiomyopathy and those with anterior acute myocardial infarction

BACKGROUND

There has not been a comparison of the electrocardiographic (ECG) finding of ST-segment elevation in the precordial leads in patients with takotsubo cardiomyopathy (TC) and those with anterior acute myocardial infarction (AMI), with regard to the location of the culprit lesion.

METHODS AND RESULTS

The present study evaluated 18 patients with TC, and 85 with anterior AMI who were divided into 3 groups: group A had the culprit lesion proximal to both the first septal branch (S1) and the first diagonal branch (D1), group B had the culprit lesion proximal to either S1 or D1, and group C had the culprit lesion distal to both S1 and D1. In patients with TC, reciprocal ST-segment depression in the inferior leads was observed less frequently than in patients in groups A (p<0.0001) and B (p=0.0002), and abnormal Q waves and ST-segment elevation in the inferior leads were observed more frequently than in group A (p=0.0007, p=0.0057, respectively). The ECG findings in TC did not differ from those in group C.

CONCLUSION

Electrocardiographic findings may differentiate TC from AMI with a proximal lesion of left anterior descending coronary artery, but not those with distal lesions.