Biomedical subjects
Publications and source records attributed to R H Selvester.
A retrospective evaluation was performed of patients who underwent exercise tests and angiography and 50 ambulatory normal subjects who underwent only exercise testing. We found that when deltaST depression of 0.5 mm was combined with deltaR-wave decrease of 1 mm, the sensitivity and specificity were improved.
It is clinically important to estimate the size of a myocardial infarction (MI) to predict patient prognosis, to determine the ability of a therapy to limit its size, and to evaluate its effect on left ventricular function. Various electrocardiographic methods have been used for these purposes but their accuracies have not been compared with each other using an identical reference population of anatomically measured infarcts. The capability of 4 electrocardiographic scoring methods (the Selvester score, the Minnesota code, the Novacode, and the Cardiac Infarction Injury Score) to estimate MI size was compared using anatomic MI size in a group of 100 deceased patients. All patients had a standard 12-lead electrocardiogram of sufficient quality to perform manual waveform measurements and without confounding factors such as ventricular hypertrophy, fascicular block, or bundle branch block. The location and size of the left ventricular infarction was measured postmortem using the anatomic method of Ideker et al. All methods' size estimates correlated best with anatomic MI size in the anterior location (r = 0.65 to 0.89). The Selvester score was superior in estimating the sizes of inferior (r = 0.70) and posterolateral (r = 0.74) infarcts. For multiple infarcts all methods performed poorly (r = 0.18 to 0.44).
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BACKGROUND: The 32-point, 54-criteria Selvester QRS scoring system has been successfully used to estimate the size of nonacute myocardial infarction (MI). Three criteria of the system have been shown to be sensitive for the identification of nonacute MI and specific in normal control subjects. The validity of the system has not been tested in patients with cardiomyopathy of nonischemic origin. The purpose of this study was to examine the electrocardiographs (ECGs) of patients with abnormal left ventricular function but no presence of coronary disease to determine the diagnostic specificity of the MI screening criteria subset of the Selvester QRS scoring system. METHODS AND RESULTS: Six hundred ninety patients were considered. Exclusion criteria included age <10 years, cardiac transplantation, thrombolytic therapy, any angiographic evidence of coronary disease, left ventricular ejection fraction (LVEF) >60%, or history of myocardial revascularization. ECG exclusion criteria included left ventricular hypertrophy, right ventricular hypertrophy, left bundle branch block, right bundle branch block, ventricular pacing, left anterior fascicular block, left posterior fascicular block, ventricular preexcitation, and low voltage, because these confounding factors could mimic an infarct on the ECG. The 261 remaining patients were then examined for the presence of the MI screening criteria subset: (1) inferior location: Q > or =30 msec in aVF, (2) anterior location: either any Q or R< or =0.1 mV and < or =10 msec in V2, and (3) posterior location: R> or =40 msec in V1. Thirty-two of the 261 patients falsely met at least 1 of the 3 MI screening criteria, resulting in an overall specificity of 88% (vs 95% in normal control subjects, P=.0006). A specificity of 98% (n = 256) was achieved for the inferior MI screening criterion alone, whereas the anterior and posterior MI screening criteria alone achieved significantly lower specificities: 94% (n = 245) and 95% (n = 249), respectively. When the patient population was divided into LVEF <30% and LVEF > or =30%, no significant association was found between MI screening criteria and LVEF with specificities of 87% and 88%, respectively, for the 2 groups (P= .34). CONCLUSIONS: The MI screening criteria subset is relatively specific in patients with nonischemic cardiomyopathy, falsely identifying only 12% with nonacute MI. However, this specificity is lower than the 95% achieved in normal subjects. Regional accumulation of scarring caused by cardiomyopathy could result in false-positive indication of MI in the present population. Another possibility could be that some patients could have hypertrophy of the myocardium insufficient to produce positive ECG criteria for left ventricular hypertrophy or right ventricular hypertrophy but sufficient to mimic infarction.
BACKGROUND: Thrombolytic therapy can be life-saving in patients with acute myocardial infarction. However, if given too late or insufficiently selectively, it may provide little benefit but still cause serious complications and incur substantial costs. OBJECTIVE: To develop a thrombolytic predictive instrument for real-time use in emergency medical service settings that could 1) identify patients likely to benefit from thrombolysis and 2) facilitate the earliest possible use of this therapy. DESIGN: Creation and validation of logistic regression-based predictive instruments based on secondary analysis of clinical data. PATIENTS: 4911 patients who had acute myocardial infarction and ST-segment elevation on electrocardiogram; 3483 received thrombolytic therapy. MEASUREMENTS: Data were obtained from 13 major clinical trials and registries and directly from medical records, including electrocardiograms obtained at presentation. Input variables include presenting clinical and electrocardiography features; predictive models generate probabilities for acute (30-day) mortality if and if not treated with thrombolysis, 1-year mortality rates if and if not treated with thrombolysis, cardiac arrest if and if not treated with thrombolysis, thrombolysis-related intracranial hemorrhage, and thrombolysis-related major bleeding episode requiring transfusion. Together, these models constitute the thrombolytic predictive instrument. RESULTS: The predictive models generated the following mean predictions for patients in the Thrombolytic Predictive instrument Database: 30-day mortality rate, 7.1%; 1-year mortality rate, 10.9%; rate of cardiac arrest, 3.7%; rate of thrombolysis-related intracranial hemorrhage. 0.6%; and rate of other thrombolysis-related major bleeding episodes, 5.0%. They discriminated with between persons having and those not having the predicted outcome; areas under the receiver-operating characteristic (ROC) curve were between 0.77 and 0.84 for the five outcomes. Calibration between each instrument's predicted and observed served rates was excellent. Validation of the predictive instruments of 30-day and 1-year mortality, done on a separate test dataset, yielded areas under the ROC curve of 0.76 for each CONCLUSIONS: After the basic features of a clinical presentation are entered into a computerized electrocardiograph, the predictions of the thrombolytic predictive instrument can be printed on the electrocardiogram report. This decision aid may facilitate earlier and more appropriate use of thrombolytic therapy in patients with acute myocardial infarction.
BACKGROUND: Myocardial salvage is most likely to occur when thrombolytic therapy is administered within 4 to 6 hours of the onset of symptoms of myocardial infarction. The impact of delays within this early time period on final myocardial infarct size are unknown. The purpose of this study was to quantitate the relation between final myocardial infarct size and duration of symptoms before initiation of thrombolytic therapy in patients treated within 6 hours of symptom onset. METHODS AND RESULTS: The findings from patients in four prospective randomized trials of thrombolytic therapy were combined for analysis. The study population consisted of 432 patients presenting within 6 hours of onset of symptoms of first acute myocardial infarction who met ECG criteria that allowed estimation of myocardial area at risk before treatment with thrombolytic therapy and who had thallium-201 myocardial infarct-size measurements performed several weeks after infarction. ECG analysis revealed no difference in myocardium at risk for infarction as a function of duration of symptoms before initiation of thrombolytic therapy. In contrast, univariate and multivariate analysis showed that final infarct size was highly dependent on duration of symptoms before initiation of therapy. Each 30-minute increase in symptom duration before thrombolytic therapy was associated with an increase in infarct size of 1% of the myocardium. Final infarct size in patients treated 4 to 6 hours after symptom onset was indistinguishable from patients who did not receive thrombolytic therapy. CONCLUSIONS: These findings suggest that for patients treated within 4 to 6 hours of the onset of symptoms, there is a progressive decline in the extent of myocardium salvaged as the duration of symptoms before therapy increases. These results support efforts to minimize the time delay between symptom onset and initiation of reperfusion therapy in all eligible patients.
The authors have proposed a new four-step screening algorithm to detect asymptomatic coronary artery disease (CAD) in flight school candidates, cadets, and rated flyers of the Unites States Air Force (USAF). In step 1, the USAF Armstrong Laboratory (USAF/AL) risk profile and improved 16-lead high-resolution electrocardiogram/vectorcardiogram will be recorded at baseline. On routine follow-up evaluations, quantitative serial comparisons will be performed by the method of Kornreich. In step 2, beginning with flight school candidates and cadets, all three groups will be studied by the ultrafast computed tomograph (CT) protocol. Those candidates positive for coronary calcium will be studied by coronary angiography and ventriculography, and their eligibility for continued rated flight status will be determined by present criteria. In step 3, those candidates negative for coronary calcium by ultrafast CT will then be screened by the newly defined and improved high-sensitivity treadmill exercise test criteria. In step 4, candidates with a positive treadmill exercise test result, or who are also found in the upper quintile of the USAF/AL risk profile, wild also have exercise nuclear wall motion studies and perfusion scans. If these are abnormal and suggestive of myocardial ischemia, this subset will also be studied by heart catheterization and coronary angiography, and their eligibility for continued rated flight status will be determined by present criteria. The incidence of coronary calcium/no calcium for each degree of stenosis in the 6,000 flyers in each quintile was used to develop the following projections: (1) that more than 3 of 4 rated flyers with unsuspected CAD, and (2) more than 9 of 10 with severe flow-limiting CAD can be identified by these upgraded screening procedures. Evidence is herein presented that these enhancements will result in a major (5-8-fold) increase in case finding of this disease. Based on the estimate of four lost high-performance aircrafts per year from sudden incapacitation of the pilot due to CAD, when this four-step screen is fully operational, it can be expected to reduce the $80 million annual losses to the United States government from CAD by 85%, a savings of $68 million per year.
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OBJECTIVES: The purpose of this study was to determine the time course of the appearance of abnormal Q waves on the electrocardiogram (ECG) over the first 6 h of symptoms of myocardial infarction and to determine what implications, if any, such Q waves have for the efficacy of thrombolytic therapy. BACKGROUND: Severe myocardial ischemia can produce early QRS changes in the absence of infarction. Abnormal Q waves on the baseline ECG may not be an accurate marker of irreversibly injured myocardium. METHODS: Data from 695 patients who had no past history of myocardial infarction and whose admission ECG allowed prediction of myocardial infarct size in the absence of thrombolytic therapy (Aldrich score) were pooled from four prospective trials of thrombolytic therapy. The presence and number of abnormal Q waves on each patient's initial ECG were recorded. Four hundred thirty-six patients had left ventricular infarct size measured using quantitative thallium-201 tomography a mean (+/- SD) of 52 +/- 43 days after admission. RESULTS: Of patients admitted within 1 h of symptoms, 53% had abnormal Q waves on the initial ECG. Both predicted and final infarct size were larger in patients with abnormal Q waves on the initial ECG independent of the duration of symptoms before therapy (p < 0.001). Despite this finding, the presence of abnormal Q waves on the admission ECG did not eliminate the effect of thrombolytic therapy on reducing final infarct size (p < 0.0001). CONCLUSIONS: Abnormal Q waves are a common finding early in the course of acute myocardial infarction. However, there is no evidence that abnormal Q waves are associated with less benefit in terms of reduction of infarct size after thrombolytic therapy.
OBJECTIVES: This study sought to determine the accuracy of the initial 12-lead electrocardiogram (ECG) in predicting final infarct size after direct coronary angioplasty for myocardial infarction and to examine which physiologic variables known to be determinants of outcome the ST segment changes most closely reflect. BACKGROUND: Myocardium at risk, collateral flow and time to reperfusion have been shown to be independent physiologic predictors of infarct size in animal and clinical models. However, such measurements may be difficult to perform on a routine basis in patients with myocardial infarction. The standard 12-lead ECG is inexpensive and readily available. METHODS: Sixty-seven patients with acute myocardial infarction, ST segment elevation and duration of chest pain < 12 h had an initial injection of technetium-99m sestamibi. Tomographic imaging was performed 1 to 8 h later (after direct coronary angioplasty), and the images were quantified to measure perfusion defect size (myocardium at risk) and severity (a measure of collateral flow). Contrast agent injection and tomographic acquisition were repeated at hospital discharge to measure infarct size. The ST segment elevation score was calculated for each patient according to infarct location and using previously described formulas. RESULTS: ST segment elevation score correlated closest with the radionuclide measure of collateral flow (r = -0.44, p < or = 0.0001), as well as an angiographic measure of collateral flow (r = -0.38, p = 0.05). Although ST segment elevation score correlated weakly with the magnitude of myocardium at risk by technetium-99m sestamibi, it was not as strong as infarct location alone in predicting myocardium at risk ([mean +/- SD] anterior 51 +/- 13% left ventricle vs. inferior 17 +/- 10% left ventricle, p < 0.0001). ST segment elevation score was weakly associated with final infarct size (r = 0.34, p = 0.005). A multivariate ECG model was constructed with infarct location as a surrogate for myocardium at risk, ST segment elevation score as a surrogate for estimated collateral flow, and elapsed time to reperfusion from onset of chest pain. All three variables were independently associated with infarct size. CONCLUSIONS: The initial standard 12-lead ECG can provide insight into myocardium at risk and, to a greater extent, collateral flow and can consequently provide some estimate of subsequent infarct size. However, the confidence limits for such predictors are wide.
Consideration of increased T wave amplitude (tall T waves), either alone or in association with other electrocardiographic (ECG) parameters, may be beneficial for the early detection of acute transmural ischemia, and quantification of the increase might be used in quantifying the ischemic area. The primary purpose of this study was to quantify normal T wave amplitude limits according to ECG lead, sex, and age. One thousand nine hundred thirty-five subjects in two normal populations were analyzed, and the 98th percentile of the positive T wave amplitude for each ECG lead (including -aVR) was considered the upper limit of normal. Normal T wave amplitude was two times greater in the precordial than in the limb leads, and it was approximately 25% greater in men than in women in all leads. There was approximately a 10% decrease in normal T wave amplitude between 18-39- and 40-59-year-old patients and a 15% decrease between 40-59- and 60-79-year-old patients. The upper limit of normal T wave amplitudes identified in this study confirm those developed by Lepeschkin for use as means for each lead when age and sex are not considered. These limits might be incorporated into both normograms and automated ECG analysis systems to determine the presence or absence of tall T waves in patients presenting with symptoms of acute transmural ischemia.
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Therapies aimed at salvaging jeopardized myocardium in patients with acute myocardial infarction (MI) are now routine. The success of these therapies must often be estimated by non-invasive tests, such as the 12-lead electrocardiogram (ECG) or two-dimensional echocardiography. To monitor QRS changes and left ventricular (LV) function over time in patients who have received therapies aimed at myocardial salvage, it is important to know the 'spontaneous' evolution of these estimates. Consecutive MI survivors admitted in the pre-thrombolytic era with their first MI were re-studied at 4 years. Patients were excluded if they had experienced reinfarction, coronary revascularization or bundle branch block in the acute or follow-up period. A standard ECG and a two-dimensional echocardiogram were obtained prior to discharge and at follow-up. The quantitative ECG analysis was performed according to the Selvester QRS scoring method. During the two-dimensional echocardiogram each of the 20 segments of the LV were assessed to provide a wall motion score. Eighty patients with a median age of 64 years (range 40-79) were included in the study. Thirty-two had anterior and 48 inferior MI. A significant decrement in median QRS score-estimated AMI size occurred between pre-discharge and follow-up ECGs in the entire group (18.3% vs 10.5%; P<0.0001). This difference occurred in both anterior (21.6% vs 10.5%; P<0.0001) and inferior-posterior (16.5 vs 10.5%; P<0.0001) MI locations. In the anterior MI group ther was a trend towards a greater total decrease of QRS points than in the inferior-posterior MI group (42% vs 27%; P=0.10). Within the anterior MI group, more QRS points awarded in the anteroseptal leads (V1-V3) remained follow-up than in the anterosuperior and apical leads (I, aVL and V4-V6), (80% vs 49%; P=0,03).
The standard 12-lead electrocardiogram (ECG) has been developed over many years. The ECG has had a long and successful history of providing diagnostic information in clinical medicine. Cardiac arrhythmias have been elucidated by deductive reasoning from continuous ECG recordings with confirmation from electrophysiologic studies. Recently, there has been renewed interest in the morphology of the QRS complex, ST-segment, and T wave, which raises the important question of considering whether the usual method of display provides maximal diagnostic capabilities. The conventional display provides a logical visualization of precordial lead recordings representing the horizontal plane, but does not provide a logical visualization of the limb lead recordings representing the frontal plane. Many clinical problems require the consideration of serial ECGs necessitating the comparison of separate pages. An alternate format presenting serial recordings on a single page would be advantageous. Some automated ECG analysis systems already include the capability for multiple display formats, but these have not yet been widely used in clinical practice. This point of view paper introduces a new display format for the standard 12-lead ECG that includes: (1) a presentation of an orderly sequence of leads to facilitate scanning through different points in space and (2) a presentation of recordings of 12-lead sequences to facilitate scanning through different points in time. This display format could either replace or supplement the conventional ECG format.
In this early study of ongoing work with multiple regression modeling for mapping myocardial infarct (MI) into 12 left ventricular (LV) segments, promising results have been presented using electrocardiographic (ECG) QRS variables that are gender, age, and race insensitive (GARI), the GARI-QRS 12-segment multiple regression model. These include Q, R, and S duration, expressed as percentage total QRS duration, and R/Q duration, R/Q amplitude, R/S duration, and R/S amplitude variables. For version I, building 12 regression models using 68 single and 32 multiple MIs, the GARI-QRS variables correlated with pathoanatomic MI in each of 12 segments with r values ranging from .67 to .88. In version II of the model, using all MIs and 229 normal subjects, r = .73-.91. Version II predictions of MI in 12 LV segments for each subject were used to calculate the predicted total percentage LV infarct, which correlated well with that found at autopsy. The r values found were .81 for all single MIs, .73 for multiple MIs, and .80 for all MIs taken together. With refinements of the input ECG variables to include (1) improvement in the GARI-QRS variables, (2) adding a significant number of subjects with hypertrophies and conduction defects with and without MI to an expanded learning set, and (3) applying the enhanced 12-LV-segment regression models to a similar test set, it is to be expected that these regression models can be improved even further in such a way as to be applicable to general clinical populations using routine computerized ECG analysis programs.
This study reports preliminary results on 45 patients who underwent percutaneous transluminal coronary angioplasty (PTCA); 120-lead data (including the 12-lead standard electrocardiogram [ECG]) were recorded before, during, and after balloon inflation. Twenty-one patients underwent PTCA for left anterior descending coronary disease, 13 for right coronary artery disease, and 10 for left circumflex; 1 patient had combined left anterior descending and right coronary artery disease. In each patient, voltage data recorded during the various phases of the procedure were compared with the patient's own baseline data. In 18 patients, 120 leads were also recorded 24 hours after PTCA. In this study, the usefulness of the standard 12-lead ECG was investigated in locating the coronary artery being occluded, in elucidating the mechanisms of the QRS changes, and in identifying changes occurring 24 hours after completion of the procedure. Results indicate that the observation of ST elevation in the 12-lead ECG may lead to ambiguous interpretation. Also, limiting observation to ST-T patterns alone instead of including QRS changes further hampers correct identification of the involved vessel. QRS modifications during inflation are interpreted as conduction disturbances, although other mechanisms are evoked: study of surface maps may contribute to the understanding of these mechanisms. Changes present 24 hours later are visible in the standard leads, but again, in the absence of the thoracic potential distribution, these are difficult to interpret. These changes were different from those observed after cessation of inflation at the end of the procedure. It is hypothesized that next-day changes may reflect reperfusion injury and/or represent myocardial stunning. Presence of injury and reversibility of changes require further investigation. Also, biochemical markers such as creatine kinase-MB mass, creatine kinase-MB activity, myoglobin, and troponin-T may help elucidate the significance of these findings.
Previous work has shown that the ST-segment of acute myocardial infarction (MI) on the admitting electrocardiogram (or vectorcardiogram) is predictive of the final predischarge QRS score (or loss of QRS spatial vector magnitude), in terms of MI size, ejection fraction, acute MI mortality, and prognosis. Patients in the GISSI I randomized multicenter trial were risk stratified by the ECG. The relative risk (RR) of mortality in the group treated with thrombolytic therapy compared to control subjects was as follows: anterior, 0.75; inferior, 0.94; multiple, 0.61; lateral, 1.22; and prior MI 1.03, thus, indicating subsets with no benefit from thrombolysis (RR > or = 1). The RR was also 1.00 in an overlapping group of 3,539 out of 11,712 patients (30%) with ST elevation limited to two or three leads, indicating a final MI size < 10% of the left ventricle. A similar RR was demonstrated in the European Cooperative Group trial of recombinant tissue-type plasminogen activator. This study examines published data from two randomized control trials, ISIS II (n = 17,187) and GISSI II (n = 12,490), for evidence of a similar relationship. The known distribution of MI size, right ventricular infarction, and mortality data in each electrocardiographic trial subset was used to develop a risk predictive model for RR as a function of the initial ST-segment predicted MI size in each location. This further subsetting of the data revealed that 37%, that is, over 10,000 patients, in these two large trials, who did not have a prior MI or evidence of right ventricular infarction, had small MIs.(ABSTRACT TRUNCATED AT 250 WORDS)