Noninvasive assessment of cardiac function and ventricular dyssynergy by precordial Q wave mapping in anterior myocardial infarction

Echocardiography and Electrocardiography Variables Correlate With the New York Heart Association classification: An Observational Study of Ischemic Cardiomyopathy Patients

The aim of our study was to determine whether combinations of ultrasound echocardiography (UCG) and electrocardiography (EKG) parameters correlated with the functional status of ischemic cardiomyopathy (ICM) patients according to the New York Heart Association (NYHA) classification system.We assessed 536 elderly Chinese ICM patients according to the NYHA criteria, which included 196 patients with type 2 diabetes mellitus (T2DM). All of the patients underwent UCG. Transmural dispersion of ventricular repolarization was examined using EKG. Cumulative odds logistic regression was performed to evaluate associations between NYHA class and the demographic, clinical, UCG, and EKG variables based on the odds ratio (OR) and 95% confidence interval (CI). A Pearson analysis was also performed to examine correlations between the NYHA classification and the UCG and EKG variables.Based on the NYHA assessment, 140, 147, 138, and 111 patients were identified as class I, II, III and IV, respectively. A comparison of UCG and EKG variables based on T2DM status showed that CO and Tp-e differed significantly between all NYHA classes (P < .05 for all), with values of each increasing with increasing NYHA class regardless of T2DM status. Multivariate logistic regression analysis showed that the disease course (OR: 1.30; 95% CI: 1.20-1.40), heart rate (OR: 1.16; 95% CI: 1.12-1.21), T wave peak to endpoint (Tp-e; OR: 1.22; 95% CI: 1.18-1.27), dispersion of the QT interval (OR: 0.98; 95% CI: 0.95-1.22), left ventricular fractional shortening (OR: 0.82; 95% CI: 0.78-0.87), cardiac output (CO; OR: 5.58; 95% CI: 3.08-10.13) were significantly associated with the NYHA class (P < .0001 for all). A Pearson correlation analysis showed that Tp-e (r = 0.75982, P < .0001), CO (r = 0.56072, P < .0001), and stroke volume (r = -0.14839, P = .0006) significantly correlated with the NYHA class.An index consisting of Tp-e and CO will be useful for corroborating the results of the NYHA assessment of ICM patients.

Relationship between the enzymatically estimated infarct size and clinical findings in acute myocardial infarction

In 580 patients with a definite myocardial infarction (MI) and no previous MI, the enzymatically estimated infarct size was related to the clinical course including various complications. In all patients, heat-stable lactate dehydrogenase activity (EC 1.1.1.27, LD) was analyzed every 12 hours for 48-108 hours and in a subgroup (n = 170) creatine kinase activity (EC 2.7.3.2, CK) and creatinine kinase subunit B (CK B) were analyzed every 6 hours for 48 hours. The highest recorded enzyme activity was used as a rough estimate of infarct size. A positive correlation was found between serum enzyme activity and most of the clinical variables studied, such as incidence of congestive heart failure, treatment with furosemide, incidence of hypotension, cardiogenic shock, pericarditis, post myocardial infarction syndrome, AV block III, and the duration of hospitalization. We conclude that the enzymatically estimated infarct size determined by heat-stable LD, CK and CK B closely reflects the severity of the infarction.

Left ventricular function after myocardial infarction: relation between systolic time intervals and quantitative ischaemic ECG changes

Twentyfour male patients with sustained myocardial infarction (MI) were studied with 12-lead ECG and systolic time intervals (STI) 5 months after the acute episode. From the ECGs were calculated the summed voltages of the R wave (sigma R), the Q wave (sigma Q), and the ST segment deviation (sigma ST). These ischaemic ECG variables were correlated with the STI parameters of left ventricular function: LVETI, PEP and PEP/LVET. Statistically significant regression equations relating the ECG changes to the STI variables were found in anterior MI, for sigma ST in the entire series, but not in inferior MI. Thus a simple and rapid inspection of the resting 12-lead ECG gives an indirect but reliable quantitative estimate of left ventricular function in patients with a sustained myocardial infarction.

Estimation of anterior infarct size with body surface QRST integral maps in the presence of abnormal ventricular activation sequence in dogs

The possibility of estimating infarct size with body surface QRST integral (IQRST) maps was investigated in dogs. IQRST maps were constructed from 87-lead body surface ECGs, which were recorded 1 week after the production of anterior myocardial infarction during artificial pacing that simulated normal conduction, left bundle branch block, and Wolff-Parkinson-White syndrome in 11 dogs. Small differences were observed between the IQRST maps of the normal conduction and left bundle branch block models (r = 0.93, root mean square difference = 8.71 mVmsec) and between the normal conduction and Wolff-Parkinson-White models (r = 0.96, root mean square difference = 6.03 mVmsec). Summation of the QRST integral values over the body surface leads (QRST index) inversely correlated with infarct size in all three conductions models: r = 0.91 (p < 0.001) in the normal conduction model; r = -0.81 (p < 0.001) in the left bundle branch block model; and r = -0.86 (p < 0.001) in the Wolff-Parkinson-White model. These results show that IQRST maps permit noninvasive estimation of infarct size, even in the presence of abnormal activation sequences.

Correlation between various parameters derived from body surface maps and ejection fraction in patients with anterior myocardial infarction

To determine the best map parameter to predict cardiac function, various map parameters were correlated with the left ventricular ejection fraction (EF) in patients with a previous (between 3 months and 1 year) anterior myocardial infarction, but without overt congestive heart failure or ventricular dyssynergy. From 300 consecutive patients with a previous myocardial infarction, 82 patients with only an anterior infarction and who underwent cardiac catheterization and body surface mapping were selected for this study. The maps from 100 healthy subjects were used as normal controls. Body surface maps using 87 unipolar electrodes were recorded and various parameters were derived from the Q map, the QRS departure maps, the QRS isointegral (IQRS) map, and the QRST isointegral (IQRST) maps. They were compared with the angiographically determined EF. The EF was correlated with nQ (r = -0.72), four parameters derived from the QRS departure map (r ranged from -0.73 to -0.79), two parameters derived from the IQRS map (r = -0.90 and -0.86), and two parameters derived from the IQRST map (r = -0.84 and -0.85). Some parameters derived from body surface maps were found to have a very high correlation with the EF in patients who had a previous anterior myocardial infarction.

Echocardiographic prediction of left ventricular volume after myocardial infarction

Left ventricular volume is a strong determinant of survival after acute myocardial infarction. The aim of this study was to determine which clinical and echocardiographic criteria assessed early after myocardial infarction would predict later left ventricular dilation. Forty-eight patients with uncomplicated transmural myocardial infarction had echocardiography 5 to 10 days after myocardial infarction and assessment of clinical variables including peak creatine kinase and sum of electrocardiographic ST segment elevation. Left ventricular dimensions were measured from the echocardiogram in the parasternal view and also in the apical four and two chamber views at the level of the mitral leaflets, papillary muscles and apex. A cardiac wall motion score was obtained by segmental analysis of the apical views. Echocardiographic left ventricular volume was measured after 1 year from the apical views with use of a Simpson's rule method. Initial clinical and echocardiographic variables were correlated with the left ventricular volume at 1 year. There was a significant relation between the initial four and two chamber end-diastolic dimensions and the left ventricular volume at 1 year, particularly for dimensions measured at the apical level (four chamber R2 = 0.66, p = 0.0001, two chamber R2 = 0.61, p = 0.0001). Other clinical variables, parasternal left ventricular dimensions and cardiac wall motion score were not significantly related to left ventricular volume. A powerful three variable model obtained by multiple regression and including the initial two chamber apical dimension, cardiac wall motion score and body surface area accounted for 82% of the variation in left ventricular volume at 1 year.

The electrocardiographic diagnosis of acute myocardial infarction in the thrombolytic era

The 12-lead ECG remains a simple and inexpensive technique to diagnose AMI in its early phases. The diagnostic accuracy of the ECG depends upon the extent of myocardial necrosis and its localization. The ECG is most sensitive in patients with occlusion of the LAD artery, followed by the RCA and the left CFA. In 10% to 20% of patients with AMI the initial ECG either shows nonspecific changes or is normal. The correlation between the ECG and infarct-related artery varies according to the involved vessel. Classic ECG changes are seen in 90% of the LAD artery, in 70% to 80% of RCA, and in only 50% of CFA occlusions. A second important issue is the mechanism and clinical significance of reciprocal ST segment changes, which usually indicate larger MI, more impaired ventricular function, worse prognosis, and in some patients, significant disease of a noninfarct-related artery. Furthermore, the value of the ECG in estimating myocardial injury and infarct size remains controversial. The ECG plays an important role in coronary reperfusion. ST segment elevation is one of the principal criteria for instituting thrombolytic therapy, and helps predict those who will most likely benefit from coronary reperfusion. The role of the ECG in evaluating the reperfusion status after coronary thrombolysis is not clear. Rapid return to baseline or normalization of the ST segment suggests opening of the occluded vessel, though a small or negligible change does not exclude successful reperfusion.

Value of normal electrocardiographic findings in predicting resting left ventricular function in patients with chest pain and suspected coronary artery disease

PURPOSE

Characterization of left ventricular function is important in managing patients with coronary artery disease. Although many methods are available to assess left ventricular function, most are either expensive, invasive, or both. In this study, we examined the ability of normal or near-normal resting electrocardiographic findings to predict resting left ventricular ejection fraction, measured by resting radionuclide angiography, in 874 patients with chest pain and suspected coronary artery disease.

PATIENTS AND METHODS

A retrospective review was undertaken of 4,410 Mayo Clinic patients who underwent rest and exercise radionuclide ventriculography for the evaluation of chest pain and known or suspected coronary artery disease; of these, 874 patients met the inclusion criteria for the current study. A 15-lead electrocardiogram, which was interpreted by the cardiologist or cardiology trainee working in the laboratory, was obtained at the same evaluation as the radionuclide study.

RESULTS

In 590 patients with no previous history of a myocardial infarction and entirely normal resting electrocardiographic results without nonspecific ST-T wave abnormalities, the mean left ventricular ejection fraction was 0.63 +/- 0.004, and 559 patients (95%) had a normal resting ejection fraction (defined as 0.50 or more). Both nonspecific ST-T wave abnormalities (p less than 0.001) and, to a lesser degree, a history of myocardial infarction (p = 0.06) were independent predictors of an abnormal resting ejection fraction. In 185 patients with nonspecific ST-T wave abnormalities and no history of myocardial infarction, the mean left ventricular ejection fraction was 0.61 +/- 0.009, and 85% had a normal resting ejection fraction. In 36 patients with nonspecific ST-T wave abnormalities and a history of myocardial infarction, the mean left ventricular ejection fraction was 0.53 +/- 0.021, and 72% had a normal resting ejection fraction.

CONCLUSION

Thus, an entirely normal result on a resting 12-lead electrocardiogram in patients with suspected coronary disease but no history of a previous myocardial infarction is a reliable (95%) predictor of normal left ventricular function. If nonspecific ST-T wave abnormalities are noted, particularly if there is a history of a previous infarction, the predictive value of the electrocardiographic findings is diminished.

A comparison of serial 49-lead precordial ECG maps and standard 6-lead precordial ECGs in patients with acute anterior Q wave myocardial infarction

A comparison of 265 pairs of standard ECGs and 49-lead precordial maps in 20 patients with ST-segment elevations in anterior ECG leads on admission who eventually were diagnosed as having suffered an anterior Q wave myocardial infarction was carried out to investigate the diagnostic performance provided by the standard ECG in serial studies. Ten patients received intravenous methylprednisolone and 10 were given placebo on admission, and paired map-standard ECG studies were done. ST-segment elevations were taken as an index of ischemic injury and reduction of R wave amplitude or development of Q waves as a marker of developing necrosis. Methods of measurements and derivation of ECG parameters used in the analysis were the same for the standard ECGs and maps. Comparisons of percent change of five ECG-derived variables between 13 time points and admission, as assessed by the six precordial leads of the standard ECGs and the paired 49-lead maps, were made for the entire data base. A separate analysis to assess the performance of the standard ECG was carried out in a comparison of the methylprednisolone and placebo subgroups. In this latter assessment results of comparisons of the standard ECGs from the treatment and placebo cohorts were similar to the conclusions from the comparisons of the corresponding 49-lead maps. Comparisons for the entire 265 pairs of tracings by the two ECG systems demonstrated that the standard ECG is adequate to monitor quantitatively the ischemic injury and necrosis as reflected by the ECG in serial studies throughout the hospitalization and can be effectively employed in lieu of multilead precordial maps in the evaluation of therapeutic modalities for patients with anterior Q wave myocardial infarction.

Prolonged PR interval associated with an abnormal frontal plane QRS axis as an electrocardiographic criterion of left ventricular function

The aim of this study was to investigate whether, in patients who had had one or more myocardial infarctions, the electrocardiographic appearances of prolonged PR interval associated with an abnormal frontal plane QRS axis are correlated with the value of left ventricular ejection fraction. Seventy-three consecutive patients all of whom had had at least one myocardial infarction, were divided into 3 groups: Group A, 22 patients having on their electrocardiogram a prolonged PR interval and an abnormal frontal plane QRS axis; Group B, 15 patients having an abnormal QRS axis as a solitary conduction disturbance; and Group C, 36 patients without conduction abnormalities. The ejection fraction, determined in all patients by gated blood pool imaging, was found to be 30% +/- 8 (mean +/- 1 SD) in Group A, 53% +/- 21 in Group B, and 52% +/- 14 in Group C (P less than 0.001). An ejection fraction of less than 40% was found in 91% of patients in Group A, in 33.33% in Group B, and in 8.33% in Group C (P less than 0.01). Multiple segment ventricular wall contraction abnormalities were found in 50, 6.66, and 11.11%, respectively (P less than 0.001). It can be presumed, therefore, that in patients after one or more myocardial infarctions, this association of conduction abnormalities signifies a severe impairment of ventricular contractility and may identify a subgroup with a high prevalence of severely depressed ejection fraction.

QRS complex recovery during one year after acute myocardial infarction

The recovery of the ECG signs of anterior myocardial infarction has been studied in 70 patients. A significant increase in R-wave amplitude and decrease in Q-wave amplitude on 24-lead precordial mapping was observed during one year after infarction. Patients with lower initial heart rate showed a greater recovery of R- and Q-wave amplitudes, as did patients with smaller infarcts, as assessed by peak heat-stable lactate dehydrogenase (LDH).

Prediction of left ventricular function in acute anterior myocardial infarction by serum creatine kinase activity and precordial ECG mapping

Right cardiac catheterization, serial determination of creatine phosphokinase (CPK) and of CPK-MB activities, and precordial 35-lead ECG mapping were performed in 17 consecutive patients with a first anterior acute myocardial infarction (AMI) within 6 hours of the onset of symptoms. Left ventricular function as determined by the stroke index (SI, ml/m2) to mean pulmonary capillary wedge pressure (PCWP, mmHg) ratio inversely correlated either with the total CPK and CPK-MB released and with peak enzymatic activity, or with the entity of early (6th hour ECG) ST-segment elevation. Conversely, a direct correlation was found between the SI/PCWP ratio and the ratio of R to Q+S waves from late (48th hour) ECG. Residual left ventricular function after a first anterior AMI can therefore be estimated noninvasively in the individual patient by early precordial ECG mapping and by peak enzymatic activity.

Relationship between electrocardiographically estimated infarct size and morbidity during a two-year follow-up

In 587 patients with a first myocardial infarction (MI) the electrocardiographically (ECG) estimated infarct size was related to morbidity during a two-year follow-up. Patients with transmural MI (Q- or R-wave changes in standard ECG) were more often treated for heart failure and returned to work less frequently than patients with subendocardial MI (ST-T-wave changes only). There were trends indicating a higher reinfarction rate in patients with subendocardial MI, whereas angina pectoris was observed as frequently in both groups. In a subset of patients with anterior MI, infarct size was estimated from the total Q- and R-wave amplitude in 24 precordial leads 4 days after arrival in hospital. A positive relationship was observed between ECG-estimated infarct size and treatment for heart failure, and patients with smaller infarctions according to ECG criteria returned to work less frequently. A higher reinfarction rate was observed in patients with smaller infarctions. In patients with inferior MI there were mostly weaker correlations between ECG-estimated infarct size (Q- and R-wave changes in leads II, III, and a VF) and morbidity during the two-year follow-up.

The relationship between the electrocardiographically estimated infarct size and 1- and 2-year survival in acute myocardial infarction

In 587 patients with acute myocardial infarction (AMI) and no previous MI, electrocardiographically estimated infarct size was related to 1- and 2-year mortality. The overall mortality was higher in patients with transmural MI (Q- or R-wave changes in standard ECG) than in patients with subendocardial infarction (ST-T-wave changes in standard ECG) after 1 year (18.8% compared to 6.5% p less than 0.001) and after 2 years (22.2% compared to 13.8%, p = 0.049). When patients who were alive during primary hospitalization were analyzed separately, slightly higher mortality was found in patients with transmural MI than in subendocardial MI after 1 year (9.6% compared to 4.2%, p = 0.076) while no difference was found after 2 years (13.4% as compared to 11.7%, p greater than 0.2). In a subgroup of patients with anterior MI, precordial mapping with 24 chest leads was analyzed 4 days after arrival in hospital (n = 197). Patients were divided into quartiles according to the sum of R waves, the sum of Q waves, and the number of Q waves. There was a similar overall mortality in each quartile after 1 year and after 2 years regardless of ECG parameters studied. Neither did we find any correlation between the sum of R waves in leads II, III, and aVF on the fourth day in patients with inferior MI and overall 1- or 2-year mortality rate, although there was a trend towards higher mortality with more ECG changes.

Noninvasive assessment of left ventricular wall motion abnormalities by QRS isointegral maps in previous anterior infarction

In order to determine to what extent left ventriculographic abnormalities can be predicted from ECG changes in myocardial infarction (MI), 87 unipolar ECGs were simultaneously recorded in 22 patients with previous anterior MI with no conduction defects. We adopted a QRS isointegral mapping technique for analyzing body surface mapping data. Particular attention was given to the area where the QRS time-integral value was less than the lower limit (mean minus two standard deviations) of the normal, and this area was designated as the departure area. Left ventricular wall motion was assessed by left ventriculography and correlated with the departure area. The departure area demonstrated a close correlation with the left ventricular ejection fraction (r = -0.93) and the extent of asynergy (r = 0.74). It is suggested that the departure area reflects the loss of electromotive force due to MI. We conclude from this study that the QRS isointegral map is a useful method for evaluating left ventricular function in patients with anterior MI.

Relationship between electrocardiographically and enzymatically estimated size in anterior myocardial infarction

In 179 patients with anterior myocardial infarction the electrocardiographically estimated infarct size was related to serum enzyme activity. A precordial map containing 24 precordial positions and the peak activity of heat stable dehydrogenase (LD; EC 1.1.1.27) were used. A positive correlation was found between the area at risk (initial sum of ST-elevation) and the peak LD activity (r = 0.48 - 0.55; p less than 0.001). When the final Q-and R-wave amplitude were related to peak enzyme activity a better correlation was observed (r = 0.56 - 0.68; p less than 0.001). The sum of R-waves (sigma R) and the sum of Q-waves (sigma Q) in the 24 precordial leads were related to sigma R and sigma Q in five precordial standard leads. A good correlation was found between the two ECG methods (r = 0.75 - 0.83; p less than 0.001), indicating that an increased number of precordial leads gives information regarding the extent of infarction similar to that obtained with the routinely used standard leads. It is concluded that in the individual patient, serum enzyme activity and the final Q-and R-wave changes can give different information about infarct size. If, however, these two independent methods are used in a large number of patients in intervention studies they will probably give similar information about relative influence of the intervention on the mean infarct size.

Development of congestive heart failure after treatment with metoprolol in acute myocardial infarction

In a double blind study of metoprolol in the treatment of suspected acute myocardial infarction 698 patients (study group) received metoprolol and 697 a placebo (control group). Metoprolol was given in an intravenous dose of 15 mg as soon as possible after admission to hospital followed by 50 g by mouth four times a day for two days and thereafter 100 mg twice a day for three months. A placebo was similarly given. Congestive heart failure occurred in a similar percentage of patients in both the study (27%) and the control groups (30%). Its severity was estimated by calculating the total dose of frusemide given during the first four days in hospital. Less frusemide was given to patients treated with metoprolol compared with those given a placebo in the total series. An appreciably lower total dose of frusemide was given to patients included in the trial less than or equal to 12 hours after the onset of pain and treated with metoprolol compared with a placebo, while no difference was seen among patients treated later. The initial heart rate, systolic blood pressure, and infarct site affected the results.

Relationship between electrocardiographically estimated infarct size and clinical findings in inferior myocardial infarction

In 270 patients with acute inferior wall myocardial infarction (MI) and no previous MI, Q- and R-wave changes in leads II, III, and aVF in a 12-lead standard ECG were related to the clinical course during hospitalization and 3-month follow-up. Patients with ECG-defined transmural MI showed a higher incidence of tachycardia, high degree of AV block, congestive heart failure (CHF), and pericarditis than patients with nontransmural MI. In a subgroup including 226 patients, the series was divided into quartiles according to the sum of Q- and R-wave changes in leads II, III, and aVF 4 days after arrival in hospital. A weak correlation between ECG-determined infarct size and the incidence of complications such as congestive heart failure (CHF), need for furosemide, and pericarditis, as well as the duration of hospitalization was observed. It is concluded that ECG-determined infarct size from leads II, III, and aVF in inferior MI is associated with the clinical course, although it cannot predict the outcome in the individual patient.

Relationship between electrocardiographically estimated infarct size and clinical findings in anterior myocardial infarction

In 292 patients with anterior myocardial infarction (MI) and no previous MI the electrocardiographically estimated infarct size was correlated with clinical findings during hospitalization and 3-month follow-up. Patients with ECG-defined transmural MI had a higher incidence of different types of complications, such as congestive heart failure (CHF), hypotension, pericarditis, and a longer duration of hospitalization than patients with nontransmural MI. In a subgroup including 182 patients of the total series, a precordial map containing 24 electrodes was used. The sum of R waves (sigma R), the sum of Q waves (sigma Q), the number of Q waves, and sigma R - sigma Q were calculated 4 days after arrival in hospital to estimate the size of infarction. There was generally a correlation between these ECG variables and different clinical findings, such as incidence of CHF, hypotension, pericarditis, and the duration of hospitalization. It is concluded that the ECG determined infarct size in anterior MI in a majority of patients correlates with the incidence of different types of complications in acute myocardial infarction. In the individual patient, however, the risk of developing complications cannot be predicted by ECG changes.

The relationship between electrocardiographic changes and early mortality rate in acute myocardial infarction

In 587 patients with acute myocardial infarction (AMI) and no previous MI, electrocardiographically estimated infarct size was related to three-month mortality. Mortality was found to be higher in patients with transmural MI (Q or R-wave changes in standard ECG) than in patients with subendocardial infarction (ST-T wave changes in standard ECG). In patients with anterior MI, precordial mapping with 24 chest electrodes was analyzed four days after arrival in hospital (n = 197). Neither the sum of R-waves, the sum of Q-waves, nor the number of Q-waves correlated significantly with early mortality, although there was a trend towards higher mortality among patients with more pronounced ECG changes. Finally, in patients with inferior AMI (n = 230), neither the sum of R-waves nor the sum of Q-waves in leads II, III and aVF on the fourth day influenced three-month mortality. However, when subtracting the sum of Q-waves from the sum of R-waves, there was a significant correlation between the estimated infarct size and the early mortality.

Electrocardiographic changes after myocardial infarction as indicators of deranged regional left ventricular wall motion. A serial M mode echocardiographic mapping study

Electrocardiographic and echocardiographic findings were compared in 44 patients with a first transmural infarction. Each patient was investigated on days 1, 2, 10, and 360. The electrocardiogram was classified according to QRS and ST segment changes. Local left ventricular function was determined from mean systolic wall velocity measurements by an M mode echocardiographic mapping technique in 10 of 16 segments suitable also for electrocardiographic evaluation. Mean systolic wall velocity was corrected for differences in anterior and inferior wall motion. Wall motion was normal in segments without QRS or ST changes throughout the study. All segments with QRS or ST changes showed significantly lower corrected systolic wall velocity values during the acute stage. Segments with ST depression, alone or in combination with a minor Q wave, had corrected mean systolic wall velocity values similar to those of normal segments after one year. Segments with major Q waves and all segments with ST elevation showed reduced corrected mean systolic wall velocity values throughout the study. Segments with ST elevation, irrespective of Q waves, showed the most severely reduced wall motion with significantly lower corrected mean values than segments with minor or major Q waves without ST elevation on days 10 and 360. Thus when electrocardiograms are used for defining local left ventricular function, consideration must be given to the phase of illness, QRS morphology, and presence of ST segment elevation.

Isointegral analysis of body surface maps for the assessment of location and size of myocardial infarction

To estimate the location and size of myocardial infarction (MI), an isointegral mapping technique was adopted from among various body surface electrocardiographic mapping techniques. QRS isointegral and departure maps were made in 35 patients with MI. These patients were separated into 3 groups, based on the location of MI: anterior, inferior, and anterior plus inferior. The severity and location of MI were estimated by thallium-201 myocardial perfusion imaging and the degree of scintigraphic defect was represented by a defect score. The extent of MI was expected to be reflected on the QRS isointegral maps as a distribution of negative QRS complex time-integral values. However, the extent and the location of MI were hardly detectable by the original maps. A departure mapping technique was then devised to observe the distribution of departure index on the body surface. Particular attention was given to the area where the departure index was less than -2, and this area was expected to reflect the location and size of specific abnormality of isointegral map due to MI. There were strong correlations between departure area and defect score in the anterior and inferior MI cases (r = 0.88 and r = 0.79, respectively). However, patients with anterior MI plus inferior MI showed no such correlation. Q-wave mapping was compared with QRS isointegral mapping, and QRS isointegral mapping was found to be more accurate in the estimation of the location and size of MI than Q wave mapping. Thus, QRS isointegral mapping, especially departure mapping, is more useful and convenient for detecting the location and size of MI than methods such as isopotential and Q wave mapping.

The electrocardiogram as an index of left ventricular function in coronary heart disease

To determine the utility of conventional electrocardiographic criteria for the assessment of left ventricular function, we applied pre-determined criteria to the analysis of the ECGs of 171 patients with chronic coronary disease. Eighty patients had no criteria for infarction. Seventeen had a criterion for anterior, 59 a criterion for inferior, three for strict lateral, four for true posterior and eight for combined infarction. Of the 59 with inferior infarction, 25 had QaVF greater than or equal to 0.03 sec. These 25 together with the 25 with anterior or combined infarction constituted a subgroup of 50 patients which included 35 of the 44 (80 percent) of those with an ejection fraction less than 0.50. Among the remaining 121, only nine (7 percent) had a depressed ejection fraction. Thus, the ECG criteria identified correctly 147 (86 percent) patients with regard to the presence or absence of left ventricular dysfunction.

The QRS scoring system for estimating myocardial infarct size: clinical, angiographic and prognostic correlations

The relation between a QRS score derived from the routine electrocardiogram and left ventricular function was investigated in 181 patients after myocardial infarction. Patients with left ventricular hypertrophy and conduction defects were excluded. The QRS score correlated closely with the severity of wall motion abnormalities and left ventricular ejection fraction. The more severe the dyssynergy, the higher the QRS score (hypokinesia = 3.0; akinesia = 5.4; dyskinesia = 9.1). The left ventricular ejection fraction (percent) = 66 - (3.3 x QRS score) (correlation coefficient [r] = -0.81, probability [p] less than 0.001). With use of this regression equation, the QRS score predicted angiographic left ventricular ejection fraction to within 12% of the angiographic ejection fraction in 29 of 30 additional patients studied prospectively. The QRS score was also related to clinical functional class. The worse the clinical manifestation of left ventricular dysfunction, the higher the QRS score (Killip class I = 3.5; class II = 6.5; class III = 7.1). A QRS score greater than or equal to 7 had a specificity of 97% and a sensitivity of 59% for predicting an ejection fraction of less than 45%. Patients with a QRS score of 7 or greater had severe wall motion abnormalities, higher peak serum creatine kinase levels, higher prevalence of multivessel coronary disease, poor clinical functional class and an unfavorable outcome. The QRS score provides an inexpensive, clinically useful estimate of left ventricular function after myocardial infarction and can identify patients at high risk.

Limitations of electrocardiographic scoring systems for estimation of left ventricular function

Four electrocardiographic scoring systems for the assessment of left ventricular function or presence of myocardial infarction were evaluated in 231 patients with coronary artery disease. Electrocardiographic scores were compared with radionuclide ejection fraction and thallium perfusion studies. The correlation between Wagner's modified QRS score and ejection fraction was only fair (r = -0.60). Askenazi's sum of R wave voltage score correlated poorly with ejection fraction (r = 0.44), as did Gottwik's sum of voltage score from the Frank lead electrocardiogram (r = 0.44). Rautaharju's Cardiac Infarction Injury Score did not reliably predict presence of infarction in the patient group, nor did it correlate well with ejection fraction (r = -0.49). None of the correlations were significantly improved when only patients with a history of a myocardial infarction, a thallium defect compatible with a scar or a diagnostic Q wave were considered. Although Wagner's QRS score correlated best with ejection fraction, all scoring systems had limited clinical usefulness for estimating ejection fraction.

Effects of early administration of a highly purified hyaluronidase preparation (GL enzyme) on myocardial infarct size

79 patients with suspected myocardial infarction entered a randomised trial to establish the safety of early intravenous administration of a highly purified hyaluronidase preparation (GL enzyme) and to assess its effects on eventual infarct size as measured by electrocardiographic, enzymatic, and scintigraphic criteria. Of the 71 patients with infarction, 35 received GL enzyme and 36 placebo within 6 h of the onset of chest pain. GL enzyme injected into a peripheral vein produced no adverse changes in the clinical, haemodynamic, biochemical, or haematological variables studied. GL enzyme reduced precordial electrocardiographic indices of infarct size as reflected by a diminution (p less than 0.02) in the degree of both R wave loss and Q wave development. In addition, the number of leads developing pathological Q waves (N delta Q greater than or equal to 2), a sign of progression from ischaemia to necrosis, was reduced (p less than 0.05) after GL enzyme treatment. However, there were no significant differences in infarct size as measured by cumulative creatine kinase MB isoenzyme release or technetium-99m pyrophosphate scintigraphic infarct area, or in clinical outcome during the hospital stay. Interpretation of the enzymatic and scintigraphic data was complicated by chance bias in pre-treatment randomisation which resulted in more (p less than 0.05) patients with severe haemodynamic impairment (and hence probably larger infarct sizes) entering the GL enzyme group. Nonetheless, a favourable effect of GL enzyme on infarct size was demonstrated by precordial electrocardiographic QRS mapping, here each patient acts as his or her own control.

A QRS scoring system for assessing left ventricular function after myocardial infarction

A QRS scoring system for estimating the size of a myocardial infarct was evaluated in 55 patients who did not have left ventricular hypertrophy or conduction abnormalities. Serial 12-lead surface electrocardiograms were scored according to a 29-point system based on the duration of Q and R waves and on the ratios of R-to-Q amplitude and R-to-S amplitude. The scores were proportional to the severity of wall-motion abnormalities, which was determined by radionuclide blood-pool scanning and which correlated inversely with the radionuclide-determined left ventricular ejection fraction (LVEF). A score less than 3 was 93 per cent sensitive and 88 per cent specific for both severe regional dyssynergy and major depression of the global LVEF. The following equation was used to estimate the LVEF from the QRS score: LVEF (%) = 60 - (3 x QRS score). After acute myocardial infarction, an electrocardiogram can provide important indirect quantitative information about left ventricular function.

The influence of electrode placement in the reconstruction and analysis of body surface potential maps from limited thoracic arrays

Despite their capacity to indicate abnormality outside the scope of routine electrocardiography, body surface maps remain extensive, time-consuming research procedures. By contrast, a 35-electrode grid which sums precordial ST segment deviations has received wide attention as a clinical monitor of acute myocardial infarction. First, this study examined the feasibility of recovering essential data from a small electrode array to construct maps equal to those obtained from a much larger array. Such a small-array technique would offer economy, easy application, plus the comprehensiveness and clinical correlation of the large system. Second, the relationships between map, small-array and a 35-component equivalent multipolar generator were explored for a transformation system which both expands the small-array data to map displays and reduces such data to non-redundant waveforms. Comparisons were made between direct maps and those derived from two 35-electrode sets on normal subjects and patients with myocardial infarction or cardiomyopathy. Electrode placement did not conform to the conventional rectangular grid; for one, the electrodes encircled the thorax symmetrically; in the other they were statistically selected for signal information content. We found 1) symmetrical electrode placement and analytic reconstruction of maps from multipolar lead components consistently reproduced known maps well (.91 correlation, 120 microvolts error); but 2) empirical electrode placement and statistical prediction of known maps averaged .99 correlation and 20 microvolts error for the normal training population and .97 and 60 microvolts for the abnormal test sample. Worsening occurred when placement and prediction methods were mixed; however, maps reconstructed by the empirical-statistical approach reduced to a reasonable approximation of equivalent generator scalar leads.

Value of electrocardiogram in predicting and estimating infarct size in man

The value of the electrocardiogram in assessing infarct size was studied using serial estimates of the MB isomer of creatine kinase (CK MB) in plasma, serial 35 lead praecordial maps in 28 patients with anterior myocardial infarction, and serial 12 lead electrocardiograms in 17 patients with inferior myocardial infarction. In patients with anterior infarcts, sigma ST, sigma R, sigma Q, sigma R/(Q+S), and the number of sites with ST elevation more than 2 mm or with QS waves, were obtained from each map. Correlation between both maximum sigma Q and maximum sigma ST with cumulative CK MB was highly significant. There was also a significant correlation between sigma R and sigma R/(Q+S) with cumulative CK MB. There was no significant correlation between maximum number of sites with ST elevation or with Q or QS waves and cumulative CK MB. Maximum sigma ST and number of sites with ST elevation predicted maximum sigma Q and number of sites with QS or Q waves at a time when infarction was not complete. In patients with inferior infarcts, there was a significant correlation between maximum sigma Q and maximum sigma ST in leads II, III, and a VF, and cumulative CK MB. This study shows that all the waves in the electrocardiogram are useful in assessing infarct size. The fact that maximum sigma ST predicts final sigma Q may be used to assess the efficacy of interventions designed to salvage ischaemic myocardium.

The single precordial lead for ST segment monitoring: comparison with the multiple lead map

ST segment elevation, used as an index of the relative extent of myocardial ischemic injury, was measured using a single precordial lead located at the point of maximum ST elevation. ST changes were followed for two hours after acute coronary occlusion in pigs, and were compared to the sum of ST elevation recorded with an 18 lead precordial map. Some animals were subjected to Reperfusion (n = 12), others to infarct extension (n = 10), while a control group (n = 9) was followed without an ST-modifying intervention. Correlation between sigmaST and ST in the single lead was good, with a correlation coefficient of 0.844 at 360 points of comparison. Time to peak ST elevation using the single lead technique was comparable to that using the 18 lead map. Changes in the ST elevation using both techniques were similarly reduced following reperfusion, increased following extension, and followed a similar downslope pattern in the unmodified infarct group. This single lead technique offers the advantage of simplicity of use without sacrifice of accuracy. Its use can facilitate clinical studies of myocardial ischemic injury and its modification.