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Background and Purpose: The first purpose of the study was to optimize empirically the detection of prior inferior myocardial infarction (IMI) and prior anterior myocardial infarction (AMI) by electrocardiogram (ECG). The second purpose was to compare the diagnostic performances of the new criteria with those of 3 widely used commercial diagnostic ECG algorithms., Materials and Methods: We analyzed the digital ECG data from 1138 subjects with suspected coronary artery disease in whom the presence or absence of prior IMI or AMI was documented by coronary angiography and left ventriculography. We used receiver operating characteristic curves to develop the new criteria for prior IMI and AMI using a training set of 562 subjects and then tested their diagnostic performances using a separate test set of 576 subjects. In both the training and test sets, we used χ(2) test to compare the performances of the new criteria with those of 3 commercial computerized diagnostic algorithms., Results: The best criterion for prior IMI was the algebraic sum of the Q and T amplitudes in leads III and aVF. Its sensitivities/specificities were 71%/98% and 74%/98% in the training and test sets, respectively. The best criterion for prior AMI was the algebraic sum of the Q, R, and T amplitudes minus the Q duration in leads V(2), V(3), and V(4). Its sensitivities/specificities were 68%/98% and 65%/98% in the training and test sets, respectively. In both the training and test sets, these diagnostic performances were generally superior to those of the 3 commercial algorithms., Conclusions: Using digital ECG data, we developed and tested new criteria for prior IMI and AMI whose diagnostic performances are generally superior to each of 3 widely used commercial ECG diagnostic algorithms., (Copyright © 2012 Elsevier Inc. All rights reserved.)

Background: Electrocardiogram-derived grades of ischemia at the time of patient presentation with acute myocardial infarction have proved useful in predicting the salvageability by reperfusion therapy, final infarct size, severity of left ventricular dysfunction, and short- and long-term prognosis., Subjects and Methods: The Sclarovsky-Birnbaum Ischemia Grading System based on the relation between the acute appearances of the T wave, the ST segment, and the QRS complex was considered as a means of enhanced ECG analysis in this group of patients. The evaluation of a training population (n = 46) resulted in refinement of the published description of the Sclarovsky-Birnbaum Ischemia Grading System, and a test population (n = 50) was utilized for investigating the interobserver agreement among 5 observers in determining the grade of ischemia., Results: The agreement among the observers applying the "refined" Sclarovsky-Birnbaum Ischemia Grading System was 0.89. Complete agreement was found for the ECGs of 80% of the patients, and the most common reason for disagreement was the application of the terminal T-negativity criterion., Conclusions: The refined Sclarovsky-Birnbaum Ischemia Grading System can be performed manually with low interobserver variability. It has potential for support of the acute myocardial infarction triage decision as an electrocardiographic method for evaluating the level of ischemic protection at the time of either pre-hospital or emergency-department presentation.

The authors describe a method to account for patient-to-patient variability in electrocardiographic data. The method yielded criteria for healed inferior myocardial infarction with diagnostic performances better than those of traditional electrocardiographic parameters.

A scalar electrocardiogram (ECG), orthogonal ECG and vectorcardiogram (VCG) were recorded in 46 normal persons, 38 patients with inferior myocardial infarction (MI) and 22 patients with anterior MI proved at cardiac catheterization. The diagnostic information provided by the scalar ECG, orthogonal ECG and VCG was quantitatively analyzed and the optimal criteria for diagnosing inferior and anterior MI exhibited by each method were identified. The optimal scalar electrocardiographic, orthogonal electrocardiographic and vectorcardiographic criteria, respectively, are: For inferior MI: initial superior duration in lead aVF greater than 30 ms (sensitivity 63%, specificity 100%), superior/inferior amplitude ratio in lead Y greater than or equal to 0.2 (sensitivity 63%, specificity 96%), initial superior duration greater than 29 ms or initial superior distance greater than 0.4 mV in the frontal plane loop (sensitivity 68%, specificity 100%). For anterior MI: initial anterior duration in lead V2 less than 20 ms or initial anterior duration in lead V3 less than 25 ms (sensitivity 91%, specificity 100%), anterior/posterior duration ratio in lead Z less than 0.3 (sensitivity 73%, specificity 98%), initial anterior duration less than 15 ms in the transverse plane loop (sensitivity 64%, specificity 98%). There were no significant differences among the performances of the optimal scalar ECG, orthogonal ECG and the VCG for diagnosing inferior MI. However, the performance of the optimal scalar ECG was superior to that of the optimal orthogonal ECG and the optimal VCG for diagnosing anterior MI (chi-square = 5.20, p less than 0.02 and chi-square = 7.14, p greater than 0.01, respectively).

The scalar electrocardiograms of 64 patients with inferior wall myocardial infarction (MI) and 87 normal subjects were quantitatively analyzed to determine the respective contributions of the initial and terminal portions of the QRS to the diagnosis of inferior MI. Of the 10 best individual electrocardiographic criteria for inferior MI, 7 were Q-wave criteria and 3 were criteria that consisted of delayed termination of the QRS in leads II or III. Combining the best terminal QRS criterion (the QRS in lead III ending at least 20 ms later than the QRS in lead I) with the 7 best Q-wave criteria and the best Q-wave criterion (Q wave 40 ms or longer in lead aVF) with the 3 best terminal QRS criteria, resulted in criteria with better sensitivities and overall diagnostic performances than those of the individual criteria. Analyzing the vectorcardiograms that were also available in 26 of the patients with inferior MI and 34 of the normal subjects showed that the delayed inscription of the end of the QRS in leads II and III in patients with inferior MI is due to redirection of the terminal forces of ventricular depolarization. The terminal portions of the QRS complexes in the limb leads, considered both alone and in conjunction with traditional measurements of Q waves, contain information that is useful for diagnosing inferior MI.

This study was carried out to evaluate the possible usefulness of the VCG obtained during right ventricular pacing in the diagnosis of right ventricular necrosis. Myocardial necrosis was produced by injecting 40% formalin into the ventricular walls of 18 open-chest mongrel dogs. The injections were made in the inferior wall of the left ventricle in nine dogs (Group A) and in the inferior wall of the right ventricle in the remaining nine dogs (Group B). Analysis of vectorcardiographic QRS loops obtained during artificial pacing of the right ventricular apex was made before and 60 minutes after the injections. In Group B, but not in Group A, the injections resulted in superior displacement of initial QRS forces as indicated by measurements of time, distance, amplitude and angle. The pacing VCG, performed in serial fashion, is a specific and sensitive means of detecting right ventricular inferior wall necrosis in the experimental animal. Application of these findings to the diagnosis of myocardial infarction in humans requires further investigation.

A systematic evaluation of a large number of electrocardiographic (ECG) variables that might be useful for diagnosing anterior myocardial infarction (MI) is reported. Previous anterior MI was shown to be present or absent by cardiac catheterization in 199 patients. The best discriminator between cases and noncases of anterior MI in most patients is the presence of a Q wave of any magnitude or an initial R wave less than 20 ms in lead V2. In patients with ECG evidence of associated left ventricular or type C right ventricular enlargement, the more stringent criterion of a Q wave of any magnitude in lead V2 yielded the optimal combination of sensitivity and specificity for diagnosing anterior MI. The diagnostic performance of the proposed criteria for anterior MI is superior to that of more traditional criteria that use measurements of the absolute and relative amplitudes of precordial R waves.

New electrocardiographic (ECG) criteria for the diagnosis of inferior myocardial infarction (IMI) are proposed. The criteria are based upon the relationships between portions of the vectorcardiographic (VCG) QRS loop in the frontal plane and the corresponding portions of the ECG QRS complexes recorded in leads II and III. The application of the proposed criteria requires that the tracings be obtained with three-channel ECG machines so that the temporal relationships between the QRS complexes in lead II and those in simultaneously recorded lead III can be inspected. This type of analysis of the ECG permits important features of the contour of the VCG QRS loop to be predicted. The proposed ECG criteria for the diagnosis of IMI are: in the absence of counterclockwise rotation in the frontal plane, (1) Q waves of 30 msec or longer in lead II or (2) regression of initial inferior forces from lead III to lead II. The proposed ECG criteria were evaluated in an initial series of 333 patients and, using a blind experimental design, in a confirmatory series of 94 patients. The performance of the proposed criteria was statistically superior to that of two sets of ECG Q-wave criteria and comparable to that of the VCG criteria of Starr et al.

The vectorcardiograms of 41 patients with angiographically proved inferior myocardial infarction (MI) and 51 normal subjects were analyzed to determine whether it is the time (in milliseconds) or the distance (in millivolts) of the initial superiority directed forces of ventricular depolarization that is increased more by inferior MI, and whether parameters derived from both the initial superior time and distance can be used to detect inferior MI. The 10 best individual and the 10 best paired criteria for inferior MI involve superior distance, either alone or used in the calculation of average velocity (in volts per second), and the product of initial superior time and distance (in millivolts per second). The 2 best individual criteria for inferior MI are: inferior velocity more than 0.0065 V/s (sensitivity 71%, specificity 100%) and superior distance more than 0.39 mV (sensitivity 68%, specificity 100%). These diagnostic performances are superior to those of the best criterion that involves only the duration of the initial superior forces, i.e., initial superior time longer than 28 ms (sensitivity 49%, specificity 98%) (chi 2 = 8.42, p less than 0.005 and chi 2 = 6.31, p less than 0.025, respectively). Initial superior distance and parameters calculated from both initial superior distance and time are better vectorcardiographic criteria for inferior MI than are criteria that involve only initial superior time.

The authors evaluated the ability of criteria involving abnormalities of repolarization to diagnose healed myocardial infarction (MI). They studied the Q, R, S, and T waves and the ST-segments of the electrocardiograms (ECGs) of 60 angiographic-normal patients, 63 patients with angiographic evidence of healed inferior MI, and 33 patients with angiographic evidence of anterior MI. The best individual criteria involving repolarization were T wave amplitude less than or equal to 0.4 mm in lead II for inferior MI (specificity, 93%: sensitivity, 67%) and T wave amplitude greater than 2.4 mm for anterior MI (specificity, 100%: sensitivity, 27%). These T wave criteria enhanced the diagnostic performances of otherwise marginal QRS criteria for both inferior and anterior MI. The authors conclude that ECG criteria that involve abnormalities of the T waves are useful for diagnosing healed MI.

New electrocardiographic (ECG) criteria for diagnosing the combination of inferior myocardial infarction and left anterior hemiblock are proposed. The proposed criteria are based upon the relations between portions of the vectorcardiographic QRS loop in the frontal plane and the corresponding portions of the QRS complexes recorded by the limb leads. The application of the proposed criteria requires that the tracings be obtained with 3-channel ECG machines. The proposed criteria for the diagnosis of inferior myocardial infarction and left anterior hemiblock are as follows: (1) leads aVR and aVL both end in R waves, with the peak of the terminal R wave in lead aVR occurring later than the peak of the terminal R wave in lead aVL, and (2) a Q wave of any magnitude is present in lead II. The performance of the proposed criteria was superior to that of 10 combinations of traditional ECG criteria for inferior myocardial infarction and left anterior hemiblock.