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An increasing number of elderly people and diabetes patients with myocardial infarction go unrecognized because of painless ischemia and regression of major Q-waves over time. An increased awareness of diagnostic electrocardiogram (ECG) abnormalities other than Q-waves should allow physicians to optimize patient management. Particularly emphasized is the R-peak delay in V6, i.e. the R-peak in V6 being later than the S-peak in V2, as a sign of masked anterior myocardial infarction and ECG findings if infarcts are masked by left ventricular hemiblocks and left bundle branch block (LBBB). In left anterior hemiblocks dramatically decreased R-waves in leads II, III and AVF in conjunction with disappearance of Q-waves in leads I and aVL help to identify posterodiaphragmatic infarction. The left posterior hemiblock is itself a potent indicator of underlying posterodiaphragmatic infarction not recognized by Q-waves. In LBBB Cabrera's sign, RSR' morphology in the left-sided or inferior leads, inverse R-progression from V1 to V3 and primary repolarization abnormalities overlying the secondary T-wave changes are specific indicators of myocardial infarction. QRS-prolongation greater than 150 ms independently identifies ventricular function impairment in chronic coronary heart disease.

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In order to define which of selected ECG variables could indicate irreversibly impaired myocardial function in chronic aortic regurgitation 54 patients were stratified according to normal (> or = 50%; Group A, n = 41) or subnormal radionuclide left ventricular ejection fraction (LVEF < 50%; Group B, n = 13) late after aortic valve replacement. Preoperatively, Group B patients had a significantly greater QRS duration, greater R-peak time (RPT) prolongation in I, V5 or V6, greater RPT relative to the S-peak time of the maximum S in V1, V2 or V3 (R-peak delay) and a greater negative T-wave in I or V6, as compared with Group A. These ECG variables together with preoperative angiocardiographic LVEF and end-systolic volume index were subjected to stepwise linear discriminant analysis. The maximum RPT, angio-LVEF and the maximum RPT relative to the S-peak time of the maximum S in V1, V2 or V3 emerged as the most promising variables. Of of Group A patients 82.9% and 84.6% of Group B patients were correctly classified by the three variables. If applied separately, APT prolongation or the presence of the R-peak delay in the left-sided leads, although less sensitive, have reasonably high specificity as risk indicators of irreversibly impaired chamber function, their positive predictive value being 60 and 62.5%, respectively. In conjunction with preoperative LVEF the diagnostic contribution of the two ECG variables amounts to the greatest overall separation of postoperatively preserved from irreversibly impaired systolic function.

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Epimyocardial excitation is delayed in areas overlying infarcted myocardium. On the assumption that a delayed R peak in V6 could indicate anterior myocardial infarction (AMI) in the absence of diagnostic Q waves, the findings of angiocardiography (n = 148) and thallium scanning (n = 46) of 194 patients with suspected coronary heart disease (CHD) were compared with regard to two criteria: A (R peak in V6 precedes S peak in V2, or both peaks occur simultaneously, n = 158) and B (R peak in V6 is later than S peak in V2 [R peak delay in V6], n = 36). Of 92 patients with unconfirmed CHD, 4 fit criterion B, and 3 of these had hypertensive heart disease. In 102 patients with confirmed CHD, B was present in 15 of 79 evaluated with angiocardiography and in 17 of 23 patients who had nuclear scanning. Anterior akinesis or dyskinesis was more prevalent in group B (13 cases, 86%) than in group A (17 cases, 26.6%; p = 0.000), as were irreversible anterior thallium defects, with 16 cases in group B (94.1% and 3 cases in group A (50%) (p = 0.016). Two of the three false positives had anterior hypokinesis and one had hypertensive cardiovascular disease. B was less sensitive (59.2%) but demonstrated a specificity of 95.2% and a positive predictive value of 80.6% for the detection of AMI. If used in conjunction with C (poor or reverse R wave progression from V1 to V4, notching at the R upstroke or rsR' in V4, V5, or V6), sensitivity was decreased (38.6%) but false positives were eliminated (specificity and positive predictive value reached 100%). Thus, in the setting of CHD, B can be recommended as a marker of non-Q wave AMI, and its diagnostic reliability is maintained, even in systemic arterial hypertension, if C is taken into consideration.

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The QRS duration, maximum right precordial S amplitude, sum of amplitudes of the maximum right precordial S and T wave and T wave polarity in lead I have been analyzed in order to identify electrocardiographic predictors of left ventricular end-diastolic volume index and ejection fraction in 165 patients with complete left bundle branch block and various forms of heart disease. Multivariate analysis selected the duration, maximal amplitude of the S wave and polarity of the T wave in decreasing order of discriminatory power, which correctly identify 76.6% of the patients with a normal end-diastolic volume index less than or equal to 90 ml/m2 and a normal ejection fraction greater than or equal to 60% (n = 64) and 73.3% of those with an end-diastolic volume index greater than 90 ml/m2 or an ejection fraction less than 60% (n = 101). The comparisons of the QRS duration with the end-diastolic volume index and the ejection fraction give the best single correlations: r = 0.57 and -0.63, respectively. Multiple correlations lead to no substantial improvement of the r values: 0.06 and -0.65, respectively. A QRS duration less than 140 msec is almost always predictive of the presence of a normal end-diastolic volume index and a normal ejection fraction (sensitivity 100%, specificity 91.9%, positive predictive value 73.3%). A QRS duration greater than 170 msec is most accurate in predicting depressed left ventricular ejection fraction less than 55% (sensitivity 36.5%, specificity 98%, positive predictive value 92%). Thus, only the QRS duration provides a useful reference and guide for the evaluation of left ventricular function in the presence of left bundle branch block.

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To determine whether the ECG would be useful in the prediction of impaired left ventricular ejection performance in aortic valve stenosis, the authors evaluated 121 patients according to (1) the time relationship of the R peak in V6 to the S peak in V2; and (2) the negative P wave terminal force in V1 (Morris index, n = 109). Left ventricular ejection fraction (LVEF) was significantly depressed in patients with the R peak in V6 later than the S peak in V2 (R peak delay in V6, n = 24), compared with those with the R peak in V6 preceding the S peak in V2 or with both peaks occurring simultaneously (n = 97) (LVEF 40.8 +/- 11.8% vs 69.9 +/- 13.3%, p = .000). LVEF less than 55% was present in 87.5% of patients with the R peak delay in V6 and in only 23.7% of those without this finding. The Morris Index was significantly greater in patients with LVEF less than 55% (n = 39) than in those with LVEF greater than or equal to 55% (n = 70) (Morris Index 0.063 +/- 0.035 msec vs 0.030 +/- 0.025 msec, p = .000). The R peak delay in V6 is a highly specific (96.1%), but less sensitive (47.7%), indicator of depressed LVEF, its positive predictive value and predictive accuracy being 87.5% and 78.5%, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

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In chronic aortic valve disease the left ventricular (LV) volumes, mass and ejection fraction (EF), as well as selected Frank ECG measurements of patients with a normal counterclockwise rotation (Type A) of the horizontal QRS vector loop are compared with those of patients showing an abnormal figure-of-eight or clockwise configuration (Type B) to investigate whether the different QRS patterns reflect ventriculographic alterations or depends on a conduction delay. In aortic stenosis (AS,n = 21) and combined AS and aortic insufficiency (AS + AI,n = 23) the Type B vectorcardiograms (VCGs) correlate with significantly increased LV end-diastolic volumes (p. .01, .01, respectively) and depressed EF (p .07, .009, respectively). In pure AI (n = 39) LV volumes, mass and EF do not differ between the Type A and Type B patterns. As compared to Type B VCGs of AS (n = 6), the LV end-diastolic volume index is clearly higher in Type A VCGs of pure AI (n = 21)(p .028). The only ECG change which is significant at the p .01 level in each group is the increase of the R peak time in lead X in the Type B VCGs. This can be related to greater volume and mass only in AS and AS+ AI, but is not substantiated by equivalent ventriculographic alterations in pure AI. The findings indicate that Type B VCGs are very likely caused by a left ventricular conduction delay since they cannot be strictly correlated with increases in LV volume and mass alone.

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The extent of old posterodiaphragmatic myocardial infarction has been assessed by vector and scalar measurements of the Frank orthogonal ECG. 121 men angiographically proven to have coronary artery disease were selected on the basis of a Q/R amplitude ratio of greater than or equal to 0.25 and T wave inversion in lead aVF. They were grouped according to varying degrees of severity and the extent of wall motion disorders of the diaphragmatic and posterobasal segment of the left ventricle: (1) hypokinesis, n = 24; (2) akinesis or dyskinesis of one segment, n = 60; (3) akinesis and/or dyskinesis of two segments, n = 34. Discriminant analysis was performed by entering 11 QRS measurements. Rao's selection method permitted the 5 most decisive variables to be used for the actual analysis. They were the sum of elevation angles of the 5 initial vectors obtained at 0.01 sec intervals, the sum of magnitudes of the 3 terminal vectors at 0.01 sec intervals, the magnitude of the -0.03 sec terminal vector, the magnitude of the -0.04 sec terminal vectors, and the sum of duration of R in lead Y + R in lead Z. The classification routine could then identify correctly 70.6% of group 3, but only 50% and 46.7% of groups 1 and 2, respectively. 20.6% and 8.8% of group 3 were falsely predicted to be members of groups 2 and 1, respectively. Only 8.3% of group 1 were falsely classified as members of group 3. Thus, the electrocardiographic measurements enable transmural myocardial infarction to be predicted with confidence when the patient is classified as member of group 3.(ABSTRACT TRUNCATED AT 250 WORDS)

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Twenty scalar and vector measurements of the Frank ECG were compared between men categorized as having suffered nontransmural (n = 47) and transmural anterior myocardial infarction (n = 124), on the basis of clinical and angiocardiographic findings. Variables which showed significant differences of group means between cases with anterior wall hypokinesis and anterior wall akinesis and/or dyskinesis were submitted to linear discriminant-function analysis. The stepwise selection procedure of Rao's method demonstrated the three most decisive variables for differentiation to be: (1) the angular sum of dorsal displacement of the 5 initial QRS vectors obtained at 0.01 sec intervals (sum of negative azimuth angles); (2) the Q duration in lead Z (anterior force); and (3) the Q duration in lead X (rightward force). The classification routine can identify correctly 81% of the nontransmural and 79% of the transmural anterior infarctions. The high percentages of correctly classified nontransmural and transmural infarctions show significant diagnostic potential for patient management. From the results of discriminant-function analysis, it is apparent that the sum of negative azimuth angles derived from the dorsally directed vectors during the first half of QRS exceeds substantially the scalar variables in their contribution to differentiation of the two conditions.

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