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Biomedical subjects

W D Weaver

Publications and source records attributed to W D Weaver.

At least 55 records · Page 3Linked to original sources
PubMed1998

Risk factors for in-hospital nonhemorrhagic stroke in patients with acute myocardial infarction treated with thrombolysis: results from GUSTO-I.

BACKGROUND: Nonhemorrhagic stroke occurs in 0.1% to 1.3% of patients with acute myocardial infarction who are treated with thrombolysis, with substantial associated mortality and morbidity. Little is known about the risk factors for its occurrence. METHODS AND RESULTS: We studied the 247 patients with nonhemorrhagic stroke who were randomly assigned to one of four thrombolytic regimens within 6 hours of symptom onset in the GUSTO-I trial. We assessed the univariable and multivariable baseline risk factors for nonhemorrhagic stroke and created a scoring nomogram from the baseline multivariable modeling. We used time-dependent Cox modeling to determine multivariable in-hospital predictors of nonhemorrhagic stroke. Baseline and in-hospital predictors were then combined to determine the overall predictors of nonhemorrhagic stroke. Of the 247 patients, 42 (17%) died and another 98 (40%) were disabled by 30-day follow-up. Older age was the most important baseline clinical predictor of nonhemorrhagic stroke, followed by higher heart rate, history of stroke or transient ischemic attack, diabetes, previous angina, and history of hypertension. These factors remained statistically significant predictors in the combined model, along with worse Killip class, coronary angiography, bypass surgery, and atrial fibrillation/flutter. CONCLUSIONS: Nonhemorrhagic stroke is a serious event in patients with acute myocardial infarction who are treated with thrombolytic, antithrombin, and antiplatelet therapy. We developed a simple nomogram that can predict the risk of nonhemorrhagic stroke on the basis of baseline clinical characteristics. Prophylactic anticoagulation may be an important treatment strategy for patients with high probability for nonhemorrhagic stroke, but further study is needed.

Age Factors↗
PubMed1998

Randomized, controlled trial of RheothRx (poloxamer 188) in patients with suspected acute myocardial infarction. RheothRx in Myocardial Infarction Study Group.

BACKGROUND: Patients with acute myocardial infarction (AMI) who are not eligible for thrombolytic therapy or primary coronary angioplasty are distinguished by advanced age, complicated medical histories, relatively frequent use of prior revascularization procedures, and worse outcomes than their counterparts who are eligible for reperfusion therapy. METHODS AND RESULTS: The purpose of this randomized, controlled trial was to determine whether RheothRx, a hemorheologic agent, reduced myocardial infarct size and improved left ventricular function in patients who had suspected AMI at the time of hospital admission and were not eligible for reperfusion therapy. Patients were randomly assigned to RheothRx (n = 97) or placebo (n = 99). Patients in the two groups were similar with respect to age, sex, medical history, and clinical presentation. Enzyme evidence of AMI was present in 69% of the treatment group and 70% of the placebo group. Infarct size measured before hospital discharge was similar in the two groups (14.1% +/- 18.5% vs 11.7% +/- 14.1%, p = 0.60), although left ventricular ejection fraction was lower in the treatment group (47 +/- 14 vs 52 +/- 11, p = 0.026). Hospital mortality rate was 11.3% and 7.1% in patients receiving RheothRx and patients receiving placebo, respectively (p = 0.30). There was a higher occurrence of acute renal dysfunction in the RheothRx group (12% vs 2%, p = 0.005). Because of changes in drug dosage necessitated by the occurrence of acute renal dysfunction, the trial was stopped. CONCLUSIONS: In this study of patients who had suspected AMI and were not eligible for thrombolytic therapy, RheothRx did not decrease infarct size or favorably alter outcome. The need for effective treatment for this large patient population remains largely unmet.

Acute Kidney Injury↗
PubMed1998

Utility of the prehospital electrocardiogram in diagnosing acute coronary syndromes: the Myocardial Infarction Triage and Intervention (MITI) Project.

OBJECTIVES: We sought to determine whether the prehospital electrocardiogram (ECG) improves the diagnosis of an acute coronary syndrome. BACKGROUND: The ECG is the most widely used screening test for evaluating patients with chest pain. METHODS: Prehospital and in-hospital ECGs were obtained in 3,027 consecutive patients with symptoms of suspected acute myocardial infarction, 362 of whom were randomized to prehospital versus hospital thrombolysis and 2,665 of whom did not participate in the randomized trial. Prehospital and hospital records were abstracted for clinical characteristics and diagnostic outcome. RESULTS: ST segment and T and Q wave abnormalities suggestive of myocardial ischemia or infarction were more common on both the prehospital and hospital ECGs of patients with as compared with those without acute coronary syndromes (p < or = 0.00001). Those with prehospital thrombolysis were more likely to show resolution of ST segment elevation by the time of hospital admission (14% vs. 5% in patients treated in the hospital, p = 0.004). In patients not considered for prehospital thrombolysis, both persistent and transient ST segment and T or Q wave abnormalities discriminated those with from those without acute coronary ischemia or infarction. Compared with ST segment elevation on a single ECG, added consideration of dynamic changes in ST segment elevation between serial ECGs improved the sensitivity for an acute coronary syndrome from 34% to 46% and reduced specificity from 96% to 93% (both p < 0.00004). Overall, compared with abnormalities observed on a single ECG, consideration of serial evolution in ST segment, T or Q wave or left bundle branch block (LBBB) abnormalities between the prehospital and initial hospital ECG improved the diagnostic sensitivity for an acute coronary syndrome from 80% to 87%, with a fall in specificity from 60% to 50% (both p < 0.000006). CONCLUSIONS: ECG abnormalities are an early manifestation of acute coronary syndromes and can be identified by the prehospital ECG. Compared with a single ECG, the additional effect of evolving ST segment, T or Q waves or LBBB between serially obtained prehospital and hospital ECGs enhanced the diagnosis of acute coronary syndromes, but with a fall in specificity.

Bundle-Branch Block↗
PubMed1998

Thrombolysis-related intracranial hemorrhage: a radiographic analysis of 244 cases from the GUSTO-1 trial with clinical correlation. Global Utilization of Streptokinase and Tissue Plasminogen Activator for Occluded Coronary Arteries.

BACKGROUND AND PURPOSE: Intracranial hemorrhage (ICH) is a serious complication of thrombolytic therapy. We systematically reviewed the radiographic features of 244 cases of symptomatic ICH complicating thrombolysis for acute myocardial infarction in the Global Utilization of Streptokinase and Tissue Plasminogen Activator for Occluded Coronary Arteries (GUSTO-1) trial, correlated these observations with clinical data, and speculated on hemorrhage pathogenesis. METHODS: CT scans from 244 patients suffering symptomatic ICH were systematically reviewed for selected radiographic features, including ICH type, location, hematoma characteristics, mass effect features, hydrocephalus, and preexisting lesions. Hematoma volume was estimated by computer-assisted volumetric analysis. Data from this analysis were correlated with clinical data including hypertension, anticoagulation, age, thrombolytic regimen, and ICH timing. RESULTS: Most hemorrhages were large (median [25th, 75th percentile] volume, 72 mL [39, 118]), solitary (66%), lobar (77%), confluent (80%), and intraparenchymal (82%) with a blood/fluid level (82%) and little edema (median [25th, 75th percentile] volume, 9 mL [5, 16]). Hydrocephalus (P<.001), any one mass effect feature (P<.001), intraventricular hemorrhage (P=.022), mottled hematoma appearance (P=.050), and hematoma blood/fluid level (P<.001) were associated with higher hemorrhage volume in the radiographic analysis, as were older age (P=.005), treatment with combined streptokinase and tissue plasminogen activator (P=.034), and hemorrhage onset 8 to 13 hours after treatment (P=.008) in the clinical analysis. Subdural hemorrhage was a high-volume subgroup whose risk increased with antecedent trauma (P=.026) or syncope (P=.006). Deep intraparenchymal hemorrhage was associated with hypertension (P=.016), and multifocal ICH occurred significantly earlier after treatment (P=.002). CONCLUSIONS: Although the majority of postthrombolytic ICH are large, solitary, and supratentorial, the spectrum is diverse. Features of mass effect reflected the large volumes, and hematoma characteristics of mottling and blood/fluid levels were frequent. Thrombolysis-related coagulopathy and age appear to be the most important identifiable factors in the genesis of postthrombolytic ICH, but the hemorrhage subtype seen may reflect an interaction with other factors such as hypertension, ICH timing, antecedent head trauma, and syncope.

Cerebral Hemorrhage↗
PubMed1997

Comparison of primary coronary angioplasty and intravenous thrombolytic therapy for acute myocardial infarction: a quantitative review.

OBJECTIVE: To provide a quantitative review of the treatment effects of primary coronary angioplasty vs intravenous thrombolysis for acute myocardial infarction. DATA SOURCES: Ten randomized trials were identified through computerized bibliographic search of MEDLINE from January 1985 through March 1996 and by queries of principal investigators. STUDY SELECTION: Single-center and multicenter randomized trials comparing primary angioplasty with intravenous thrombolytic therapy among 2606 patients were included. Four trials compared angioplasty with streptokinase, 3 compared angioplasty with a 3- to 4-hour infusion of tissue-type plasminogen activator, and 3 compared angioplasty with "accelerated" administration of tissue-type plasminogen activator over 90 minutes. DATA EXTRACTION: Each investigator provided definitions and exact data for outcome events. Odds ratios (ORs), 95% confidence intervals (CIs), and P values were calculated using exact tests for categorical data. DATA SYNTHESIS: Mortality at 30 days or less was 4.4% for the 1290 patients treated with primary angioplasty compared with 6.5% for the 1316 patients treated with thrombolysis (34% reduction; OR, 0.66; 95% CI, 0.46-0.94; P=.02). The effect was similar among thrombolytic regimens, and no subgroup demonstrated a significant reduction in death. The rates of death or nonfatal reinfarction were 7.2% for angioplasty and 11.9% for thrombolytic therapy (OR, 0.58; 95% CI, 0.44-0.76; P<.001). Angioplasty was associated with a significant reduction in total stroke (0.7% vs 2.0%; P=.007) and hemorrhagic stroke (0.1% vs 1.1%; P<.001). CONCLUSIONS: Based on outcomes at hospital discharge or 30 days, primary angioplasty appears to be superior to thrombolytic therapy for treatment of patients with acute myocardial infarction, with the proviso that success rates for angioplasty are as good as those achieved in these trials. Data evaluating longer-term outcomes, operator experience, and time delay before treatment are needed before primary angioplasty can be universally recommended as the preferred treatment.

Angioplasty, Balloon, Coronary↗
PubMed1997

Patient-specific predictions of outcomes in myocardial infarction for real-time emergency use: a thrombolytic predictive instrument.

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.

Cerebral Hemorrhage↗
PubMed1997

Long-term outcome in acute myocardial infarction patients admitted to hospitals with and without on-site cardiac catheterization facilities. MITI Investigators. Myocardial Infarction Triage and Intervention.

BACKGROUND: Previous studies have documented the strong association between availability of on-site cardiac catheterization facilities and increased use of coronary angiography in patients with acute myocardial infarction (AMI). Although these studies have shown little influence of the availability of catheterization labs on hospital mortality, no long-term follow-up has been reported. METHODS AND RESULTS: From a cohort of 12,331 AMI patients admitted to 19 Seattle area hospitals, we compared long-term outcome in 7985 patients admitted to hospitals with and 4346 patients admitted to hospitals without on-site catheterization labs. During the index hospitalization, patients admitted to hospitals with on-site catheterization were more likely to undergo coronary angiography (67.1% versus 39.3%, P<.0001), coronary angioplasty (32.5% versus 13.2%, P<.0001), or coronary bypass surgery (12.5% versus 9.5%, P<.0001). At 3-year follow-up, patients admitted to hospitals with on-site catheterization labs were more likely to undergo postdischarge angiography (19.2% versus 15.2%, P=.0001) and coronary angioplasty (11.6% versus 8.2%, P<.0001). This was associated with approximately $2500.00 per patient in higher cumulative costs. Despite this higher rate of procedure use, there was no association between admission to a hospital with on-site catheterization facilities and lower long-term mortality (multivariate hazard ratio, 1.0; 95% CI, 0.93 to 1.1., the hazard being associated with admission to hospitals with on-site catheterization facilities). CONCLUSIONS: In an urban area with unconstrained patient transfer mechanisms and high overall cardiac procedure use rates, AMI patients admitted to hospitals without on-site catheterization facilities were managed with fewer procedures during hospitalization and follow-up. This more conservative treatment approach was not associated with any observed increase in long-term mortality.

Aged↗
PubMed1997

Association of gender and survival in patients with acute myocardial infarction.

BACKGROUND: During the last 5 years, many studies have produced conflicting results concerning the survival of women hospitalized with acute myocardial infarction (AMI). OBJECTIVE: To determine if gender is associated with hospital mortality and long-term survival in individuals with AMI. METHODS: This prospective study included 4255 consecutive women (34%) and 8076 (66%) men who developed AMI in 19 Seattle, Wash, area hospitals between January 1988 and June 1994. Key information was abstracted from hospital records and entered in the Myocardial Infarction Triage and Intervention registry database. In addition, data concerning survival and rehospitalization were obtained from the state of Washington and linked to the Myocardial Infarction Triage and Intervention registry. RESULTS: In comparison with men, women were 8 years older, more often had history of congestive heart failure, hypertension, or diabetes mellitus, and less often had history of myocardial infarction or coronary surgery. During hospitalization, women were less likely to undergo coronary angiography, thrombolytic therapy, coronary angioplasty, or bypass surgery. After adjustment for covariates, women were 20% more likely to die in the hospital (odds ratio, 1.22; 95% confidence interval, 1.06-1.39), yet long-term survival was similar in the 2 groups (hazard ratio, 0.97; 95% confidence interval, 0.90-1.05). The use of thrombolytic therapy or revascularization during the index hospitalization did not change the association between gender and survival. CONCLUSIONS: All things being equal, women with AMI were more likely to die in the hospital, yet survival after hospital discharge did not differ according to gender. Appropriate treatment to reduce hospital mortality in women is needed.

Aged↗
PubMed1997

Absence of association between insurance copayments and delays in seeking emergency care among patients with myocardial infarction.

BACKGROUND: The requirement of copayments for emergency care is thought to control costs by reducing "inappropriate" visits to the emergency department. However, requiring copayments may lead to adverse outcomes if patients delay seeking care for emergency conditions. To determine whether such requirements are associated with delays in seeking care, we examined the length of time from the onset of symptoms to arrival at the hospital among patients with myocardial infarction who did or did not have required insurance copayments. METHODS: All patients were enrolled in a single health maintenance organization (HMO) and presented with myocardial infarction at 1 of 19 hospitals in King County, Washington, from 1989 through 1994. There were 602 patients whose health insurance required a copayment for emergency department care (range, $25 to $100) and 729 patients with no copayment requirement. Data on the time to presentation were obtained from a review of ambulance and hospital records. RESULTS: The median length of time from the onset of symptoms to arrival at the hospital, as adjusted for age, sex, and race, was 135 minutes for the copayment group and 137 minutes for the group with no copayment (95 percent confidence interval for the difference, -19 to +16 minutes). There was no significant association between the presence or absence of a copayment requirement and the time to arrival at the hospital after adjustment for calendar year, income, educational level, cardiac history, or clinical symptoms. Since some patients may be unaware of their copayment requirement, we performed a subgroup analysis of data on patients who had a previous visit to the emergency department with the same copayment status - that is, of patients who were likely to know about their copayment. This analysis also showed no significant association between the requirement for a copayment and delays in seeking treatment. CONCLUSIONS: For privately insured patients in this HMO, the requirement of modest, fixed copayments for emergency services did not lead to delays in seeking treatment for myocardial infarction.

Adult↗
PubMed1997

The physician's role in minimizing prehospital delay in patients at high risk for acute myocardial infarction: recommendations from the National Heart Attack Alert Program. Working Group on Educational Strategies To Prevent Prehospital Delay in Patients at High Risk for Acute Myocardial Infarction.

Physicians and other health care professionals play an important role in reducing the delay to treatment in patients who have an evolving acute myocardial infarction. A multidisciplinary working group has been convened by the National Heart Attack Alert Program (which is coordinated by the National Heart, Lung, and Blood Institute of the National Institutes of Health) to address this concern. The working group's recommendations target specific groups of patients: those who are known to have coronary heart disease, atherosclerotic disease of the aorta or peripheral arteries, or cerebrovascular disease. The risk for acute myocardial infarction or death in such patients is five to seven times greater than that in the general population. The working group recommends that these high-risk patients be clearly informed about symptoms that they might have during a coronary occlusion, steps that they should take, the importance of contacting emergency medical services, the need to report to an appropriate facility quickly, treatment options that are available if they present early, and rewards of early treatment in terms of improved quality of life. These instructions should be reviewed frequently and reinforced with appropriate written material, and patients should be encouraged to have a plan and to rehearse it periodically. Because of the important role of the bystander in increasing or decreasing delay to treatment, family members and significant others should be included in all instruction. Finally, physicians' offices and clinics should devise systems to quickly assess patients who telephone or present with symptoms of a possible acute myocardial infarction.

Algorithms↗
PubMed1997

The prehospital electrocardiogram in acute myocardial infarction: is its full potential being realized? National Registry of Myocardial Infarction 2 Investigators.

OBJECTIVES: This study sought to examine the management and subsequent outcomes of patients with a prehospital electrocardiogram (ECG) in a large, voluntary registry of myocardial infarction. BACKGROUND: The prehospital ECG has been proposed as a means of rapidly identifying patients with acute myocardial infarction who might be eligible for reperfusion therapy. METHODS: The characteristics and outcomes of patients with a prehospital ECG were compared with those without a prehospital ECG in the National Registry of Myocardial Infarction 2 data base. Included in the analysis were those patients who presented to the hospital within 12 h of an acute myocardial infarction. Excluded were patients with an in-hospital infarction, transferred-in referrals and self-transported patients. RESULTS: Prehospital ECGs were obtained in 3,768 (5%) of 66,995 National Registry of Myocardial Infarction 2 patients meeting study criteria. Median time from myocardial infarction symptom onset until hospital arrival was longer among those having a prehospital ECG (152 vs. 91 min, p < 0.001). However, once in the hospital, the prehospital ECG group experienced a shorter median time to the initiation of either thrombolysis (30 vs. 40 min, p < 0.001) or primary angioplasty (92 vs. 115 min, p < 0.001). The prehospital ECG group was more likely to receive thrombolytic therapy (43% vs. 37%, p < 0.001) and to undergo primary angioplasty (11% vs. 7%, p < 0.001). Also, the prehospital ECG group was more likely to undergo coronary arteriography (55% vs. 40%, p < 0.001), angioplasty (24% vs. 16%, p < 0.001) or bypass surgery (10% vs. 6%, p < 0.001). The in-hospital mortality rate was 8% in patients with a prehospital ECG and 12% in those without a prehospital ECG (p < 0.001). After adjusting for baseline covariates utilizing multiple logistic regression analysis, this mortality difference remained statistically significant (odds ratio 0.83, 95% confidence interval 0.71 to 0.96, p = 0.01). CONCLUSIONS: The prehospital ECG is infrequently utilized for diagnosing myocardial infarction, and among patients with a prehospital ECG, is associated with a longer time from symptom onset to hospital arrival. Despite these shortcomings, the prehospital ECG is a test that may potentially influence the management of patients with acute myocardial infarction through wider, faster in-hospital utilization of reperfusion strategies and greater usage of invasive procedures, factors that may possibly reduce shortterm mortality. Efforts to implement the prehospital ECG more widely and more rapidly may be indicated.

Aged↗
PubMed1997

Use and accuracy of state death certificates for classification of sudden cardiac deaths in high-risk populations.

In a large cohort of patients with known or suspected coronary disease, we evaluated the characteristics of 407 patients who died after hospital discharge and tested whether the state death certificate can be used to classify deaths as sudden cardiac versus nonsudden. Compared with a paramedic classification system based on heart rhythm, the death certificate-based classification resulted in a sensitivity that ranged from 78% to 85% and a specificity that ranged from 25% to 58%. We conclude that the death certificate can be used to identify cases of sudden cardiac death in patients at high risk; however, there is a substantial rate of false-positive sudden death classification.

Aged↗
PubMed1997

Selection of thrombolytic therapy for individual patients: development of a clinical model. GUSTO-I Investigators.

We developed a logistic regression model with data from the GUSTO-I trial to predict mortality rate differences in individual patients who received accelerated tissue plasminogen activator (TPA) versus streptokinase treatment for acute myocardial infarction. A nomogram was developed from a reduced version of this model that approximated the underlying risk of patients treated with streptokinase, and thus the benefit of TPA. The 30-day mortality rate with accelerated TPA was 0.063 versus 0.073 with streptokinase and subcutaneously administered heparin and 0.074 with streptokinase and intravenously administered heparin. No baseline patient characteristics were significantly associated with a different relative effect of TPA. Older patients and those with anterior infarction, higher Killip classification (except Killip class IV), lower blood pressure, and increased heart rate had the greatest absolute benefit with accelerated TPA. Patients with acute myocardial infarction who had more high-risk characteristics derived a greater absolute benefit from treatment with accelerated TPA versus streptokinase.

Age Factors↗
PubMed1997

Long-term implications of racial differences in the use of revascularization procedures (the Myocardial Infarction Triage and Intervention registry).

The purpose of this study was to determine if less intensive use of revascularization procedures in black patients influenced the long-term survival of patients hospitalized for acute myocardial infarction (AMI) in metropolitan Seattle. From January 1988 through June 1994, AMI developed in 420 (4%) black and 10,834 white patients before hospital discharge or death. Black patients were 6 years younger, more socioeconomically disadvantaged, and had more hypertension, diabetes, and less prior coronary surgery. Similar proportions of black and white patients received thrombolytic therapy or cardiac catheterization. However, during hospitalization, 18% of black patients underwent coronary angioplasty compared with 26% of white patients (p = 0.0004); coronary artery bypass surgery was also used less frequently in black patients (7% vs 12%, p = 0.002). Unadjusted 2-year survival was 79% for black patients and 77% for white patients (p = 0.12). After adjusting for age, clinical variables, and the use of cardiac catheterization, thrombolytic therapy, and revascularization, race was not associated with long-term survival (hazard ratio = 0.92, 95% confidence interval = 0.73 to 1.17). Despite the less intensive use of revascularization procedures in black patients in Seattle, long-term survival after AMI was similar in the two groups of patients.

Age Factors↗
PubMed1997

Admission prediction of expected final myocardial infarct size using weighted ST-segment, Q wave, and T wave measurements.

Formulas for predicting final acute myocardial infarction (MI) size from ST-segment deviation on an initial electrocardiogram were proposed by Aldrich et al. for anterior and inferior infarct locations. This study of 529 patients who did not receive thrombolytic therapy was performed to determine the effectiveness of the Aldrich formulas for predicting final QRS MI size; to propose new formulas for predicting final MI size using ST-segment deviation, Q wave, and T wave information in a development population of 322 patients; and to evaluate the new formulas in a randomly selected population of 207 patients. The Aldrich formulas achieved correlations with final infarct size of r = .40 for anterior and r = .43 for inferior MI locations in the present population which are weaker than those previously reported. Formulas that consider electrocardiographic parameters in addition to ST-segment deviation were proposed for both anterior and inferior final MI size. In the test set of 207 patients, these models explained 16.9% and 15.2% of the variation in final MI size for anterior and inferior locations respectively. They may prove useful in assessing the extent of myocardial salvage where interventions are to be tested.

Electrocardiography↗