Search PubMed⌕ Search

Biomedical subjects

F E Harrell

Publications and source records attributed to F E Harrell.

At least 91 records · Page 5Linked to original sources
PubMed1987

Outcome in suspected acute myocardial infarction with normal or minimally abnormal admission electrocardiographic findings.

Seven hundred seventy-five consecutive patients with symptoms suggestive of acute myocardial infarction (AMI) who were admitted to the cardiac care unit from the emergency room were studied; 107 had normal electrocardiographic findings and 73 had only minimal nonspecific changes. AMI subsequently evolved in 11 patients (10%) with normal electrocardiographic findings and in 6 (8%) with minimal changes, compared with 245 (41%) with frankly abnormal emergency room findings. Only 1 (1%; 95% confidence limits 0.02 to 5%) and 4 (6%; 95% confidence limits 2 to 15%) of those with normal and nonspecific initial electrocardiographic findings, respectively, had a complication for which they potentially benefited from intensive care unit intervention, although many patients received prophylactic therapy. Thus, the initial emergency room electrocardiogram can effectively separate patients into high- and low-risk groups for AMI and serious complications. Admission to a monitored intermediate care ward may be an acceptable practice in patients with chest pain and a normal or minimally changed initial electrocardiogram.

Age Factors↗
PubMed1987

Familial occurrence of accessory atrioventricular pathways (preexcitation syndrome).

Accessory atrioventricular pathways, the anatomical structures responsible for the preexcitation syndromes, may result from a developmental failure to eradicate the remnants of the atrioventricular connections present during cardiogenesis. To study whether preexcitation syndromes could also be transmitted genetically, we determined the prevalence of preexcitation in the first-degree relatives of 383 of 456 consecutive patients (84 percent) with electrophysiologically proved accessory pathways. We compared the observed prevalence of preexcitation among the 2343 first-degree relatives with the frequency reported in the general population (0.15 percent). For 13 of the 383 index patients (3.4 percent), accessory pathways were documented in one or more first-degree relatives. At least 13 of the 2343 relatives identified (0.55 percent) had preexcitation; this prevalence was significantly higher than that in the general population (P less than 0.0001). Identification of affected relatives may have been incomplete because clinical information was obtained only about symptomatic relatives. Patients with familial preexcitation have a higher incidence of multiple accessory pathways and possibly an increased risk of sudden cardiac death. Our data suggest a hereditary contribution to the development of accessory pathways in humans. The pattern of inheritance appears to be autosomal dominant.

Death, Sudden↗
PubMed1987

Prognostic effect of bundle branch block related to coronary artery bypass grafting.

The incidence and prognostic effect of the development of new perioperative ventricular conduction abnormalities were examined in all patients undergoing coronary artery bypass surgery at Duke University Medical Center between 1976 and 1981. Of the 913 patients included, transient (resolved before discharge) ventricular conduction abnormalities developed in 156 (17%) and persistent (until discharge) changes developed in 126 (14%). Complete right bundle branch block (BBB) was the most frequent type of new ventricular conduction abnormality, followed by left anterior hemiblock and incomplete right BBB (found in 60%, 26%, and 9%, respectively, of all patients with transient changes and 29%, 33% and 26% of all patients with persistent changes). Development of new ventricular conduction abnormalities was most strongly related to date of operation (p less than 0.0001, univariate chi 2 = 122), increasing from 2% transient and 7% persistent in 1976 to 36% transient and 22% persistent in 1981. The incidence was also higher in older patients. Preoperative ejection fraction and number of diseased vessels were related to development of perioperative ventricular conduction abnormalities but were not independently related after adjustment for other baseline characteristics. Contrary to findings in other studies, development of new perioperative ventricular conduction abnormalities, including isolated new left BBB, did not worsen the survival rate in patients followed up to 3 years after surgery.

Adult↗
PubMed1987

Effects of different paced heart rates on canine coronary occlusion and reperfusion arrhythmias.

Little information exists regarding the effect of heart rate on arrhythmias induced by coronary reperfusion. We therefore evaluated the effects of different heart rates on arrhythmias following canine coronary artery occlusion and reperfusion. Dogs were paced at either 350 msec cycle length (171 bpm; n = 30) or 480 msec cycle length (125 bpm; n = 30). They were then subjected to a 20-minute occlusion of the proximal left anterior descending coronary artery, followed by sudden reperfusion. Ligated vessel perfusion bed size (myocardial "at risk") was measured with monastral blue and red dyes. The incidence of both occlusion and reperfusion arrhythmias correlated with the myocardium at risk. Dogs paced at 171 bpm had more ventricular ectopic depolarizations (37/1000 beats vs 8/1000 beats, p less than 0.01) and a higher incidence of ventricular tachycardia during occlusion than those paced at 125 bpm (67% vs 33%, p less than 0.05). Dogs paced at the faster rate also had a higher incidence of ventricular tachycardia (83% vs 60%, p = 0.08) and ventricular fibrillation (70% vs 40%, p less than 0.05) after reperfusion. Thus, heart rate can have a substantial effect on occlusion and reperfusion arrhythmias and should be considered when making therapeutic interventions and risk assessments in this setting.

Animals↗
PubMed1987

The seasonal risk of pediatric/juvenile acute lymphocytic leukemia in the United States.

Acute lymphocytic leukemia (ALL) occurring in pediatric and juvenile patients of nine U.S.A. locations during 1973 through 1980 was investigated by epidemiologic methodology. Time series periodic regression analysis of the monthly cumulative risk for ages 0-19 years revealed evidence of trimodal periodicity at seven of the nine locations tested. Combined analyses revealed a significant effect of latitude in causing asynchrony of the trimodal patterns observed. The average risk maxima occurred in April, August, and December for U.S.A. locations with latitude above 40 degrees (Seattle, Nebraska, Iowa, Detroit, and Connecticut), and in February, July, and October for other locations (San Francisco, Utah, New Mexico, and Atlanta). Because periodic regression analysis is a complex method, independent validation tests were performed to supplement the original results. Here, the best symmetric trimodal sine curve model of each location was utilized to predict the average pattern among the remaining locations of similar latitude. These validation tests supported the existence of similar trimodal patterns for all of the southern locations, and all of the northern locations except Connecticut. The observed peaks in monthly ALL risk coincide with seasonal elevations in the rates of allergenic and infectious diseases, elements of which are capable of promoting lymphocytic proliferation and transformation. Annual disease rates were significantly lower in populations with a high proportion of Blacks or American Indians compared to predominantly Caucasian populations. The possibility that seasonal factors (environmental allergens and/or infectious agents) promote leukomogenesis via indirect mechanisms is briefly discussed.

Adolescent↗
PubMed1987

Comparison of survival of amiodarone-treated patients with coronary artery disease and malignant ventricular arrhythmias with that of a control group with coronary artery disease.

Although amiodarone is effective in the treatment of ventricular arrhythmias, it is associated with serious toxic effects. In addition, the prognosis of patients with malignant ventricular arrhythmias and coronary artery disease treated with amiodarone remains poor. The survival of 54 consecutive patients with angiographically documented coronary artery disease and symptomatic ventricular tachycardia or ventricular fibrillation treated with amiodarone was compared with that of 5,125 medically treated patients with coronary artery disease. The amiodarone group was older, with worse left ventricular function and more peripheral and cerebrovascular disease. The 1 year survival probability was 0.73 for the amiodarone group and 0.94 for the control coronary artery disease group. At 2 years of follow-up, the survival probabilities were 0.60 and 0.90 for the amiodarone and the control group, respectively. When the survival curves were adjusted for group differences in baseline prognostic characteristics (integrated as a previously published hazard score), there was no difference in the prognosis of the two groups. These findings suggest that treatment with amiodarone of malignant ventricular arrhythmias associated with coronary artery disease maintains patients on an underlying survival curve determined by the degree of myocardial dysfunction, clinical characteristics and coronary anatomy, and that amiodarone does not have a deleterious effect on survival.

Aged↗
PubMed1987

Localizing coronary artery obstructions with the exercise treadmill test.

To determine if patterns of ST depression or elevation during exercise testing provide reliable information about the location of an underlying coronary lesion, we studied 452 consecutive patients with one-vessel disease who underwent treadmill testing. Exercise ST changes were classified as elevation or depression and by lead groups involved. The ST depression occurred most commonly in leads V5 or V6 regardless of which coronary artery was involved. In contrast, anterior ST elevation indicated left anterior descending coronary disease in 93% of cases, and inferior ST elevation indicated a lesion in or proximal to the posterior descending artery in 86% of cases. Furthermore, anterior ST elevation in leads without diagnostic Q waves usually indicated a high-grade, often proximal, left anterior descending stenosis, whereas anterior ST elevation in leads with Q waves usually indicated a totally occluded left anterior descending coronary artery. Thus, ST elevation during exercise testing, although uncommon, is a reliable guide to the underlying coronary lesion, whereas ST depression is not.

Constriction, Pathologic↗
PubMed1987

Exercise treadmill score for predicting prognosis in coronary artery disease.

To determine the prognostic value of the treadmill exercise test, we evaluated 2842 consecutive patients with chest pain who had both treadmill testing cardiac catheterization. The population was randomly divided into two equal-sized groups and the Cox regression model was used in one to form a treadmill score that was then validated in the other group. The final treadmill score was calculated as follows: exercise time--(5 X ST deviation)--(4 X treadmill angina index). Using this treadmill score, 13% of the patients were found to be at high risk; 53%, at moderate risk; and 34%, at low risk. The treadmill score added independent prognostic information to that provided by clinical data, coronary anatomy, and left ventricular ejection fraction: patients with three-vessel disease with a score of -11 or less had a 5-year survival rate of 67%, and those with a score of +7 or more had a 5-year survival rate of 93%. The treadmill score was useful for stratifying prognosis in patients with suspected coronary artery disease who were referred to us for catheterization, and may provide a useful adjunct to clinical decision making in the larger population of patients being evaluated for chest pain.

Adult↗
PubMed1987

The changing survival benefits of coronary revascularization over time.

Previous comparisons of medical and surgical therapy for coronary artery disease were performed in the 1970s and may need to be updated to reflect current treatment efficacy. The purpose of this investigation was to determine the impact on long-term patient survival of changes over time in medical and surgical therapy. Among 5125 patients referred for catheterization between 1969 and 1984, 2261 underwent surgery, and 2864 received medical therapy. Survival in both medically and surgically treated patients improved over time. The improvement in medical patients was due to less sick patients being treated (a decreasing baseline risk), while that observed in surgical patients was due to refinements in care. The rate of improvement in survival over time was much greater in surgical patients, and the difference as compared with medical therapy was highly significant (treatment interaction with time p less than .0001). Estimates of 5 year survival adjusted for baseline risk factors for a patient in 1977 with one-, two-, or three-vessel disease and an ejection fraction of 0.40 were 0.88, 0.80, and 0.64 in medically treated, and 0.88, 0.87, and 0.80 in surgically treated patients. Corresponding projected estimates for 1984 were unchanged for medical patients but improved for surgical patients (0.93, 0.92, and 0.90). Thus, the projected survival benefits of surgery in 1984 appear more significant for all categories of coronary artery disease because of a differential improvement in surgical therapy. These data are relevant to therapeutic decision making for current patients and emphasize the importance of continued analysis of this topic as treatment efficacies change over time.

Coronary Artery Bypass↗
PubMed1986

Prognostic implications of angiographically normal and insignificantly narrowed coronary arteries.

The clinical presentation and prognosis of 1,977 consecutive patients with normal coronary arteries or "insignificant" coronary artery disease (CAD) (no major epicardial artery with 75% or more luminal diameter narrowing) were examined. Compared with patients with significant CAD, these patients had a lower frequency of traditional cardiac risk factors and abnormalities on the rest and exercise electrocardiogram. Cardiac survival was 99% at 5 years of follow-up and 98% at 10 years for patients with normal or insignificantly narrowed coronary arteries. Patients with normal coronary arteries differed from those with insignificant CAD in their myocardial infarction free survival rate: 99% at 5 years and 98% at 10 years for patients with normal coronary arteries, compared with 97% at 5 years and 90% at 10 years for patients with insignificant CAD. A strong relation occurred between the amount of insignificant CAD and follow-up cardiac events (chi 2 = 21.5, p less than 0.0001). Cardiac risk factors were statistically related to the risk of follow-up cardiovascular events when considered alone (chi 2 = 4.93, p = 0.026), but this relation lost significance after adjusting for the effect of coronary anatomy. Patients in both groups continued to have cardiac symptoms that resulted in frequent hospitalizations, medication use and job disability. Almost 50% in any given year of follow-up could not perform activities of high metabolic equivalent requirement and 70% had continuing symptoms of chest discomfort. Although these patients are at low risk of death, many remain functionally impaired for years.

Coronary Angiography↗
PubMed1986

Relation between electrocardiographic and enzymatic methods of estimating acute myocardial infarct size.

The extent of initial acute myocardial infarction (AMI) and subsequent patient prognosis were studied using 2 independent indicators of AMI size. Two inexpensive, readily available techniques, the complete Selvester QRS score from the standard 12-lead electrocardiogram and the peak value of the isoenzyme MB of creatine kinase (CK-MB), were evaluated in 125 patients with initial AMI. The overall correlation between peak CK-MB and QRS score was fair (0.57), with marked difference according to anterior (0.72) or inferior (0.35) location. The prognostic capabilities of each measurement varied. Peak CK-MB provided significant information concerning hospital morbidity or early mortality (within 30 days) for both anterior (chi 2 = 9.83) and inferior (chi 2 = 7.68) AMI locations; however, the QRS score was significant only for anterior AMI (chi 2 = 9.50). For total 24-month mortality, the QRS score alone provided the most information (chi 2 = 10.0, p = 0.0016), which was not improved with the addition of CK-MB (chi 2 = 0.07, p = 0.79). This study shows a good relation between these 2 independent estimates of AMI size for patients with anterior AMI location. Both QRS and CK-MB results are significantly related to early morbidity and mortality; however, only the QRS score is related to total 24-month prognosis.

Aged↗
PubMed1986

Predicting outcome in coronary disease. Statistical models versus expert clinicians.

To study the accuracy with which long-term prognosis can be predicted in patients with coronary artery disease, prognostic predictions from a data-based multivariable statistical model were compared with predictions from senior clinical cardiologists. Test samples of 100 patients each were selected from a large series of medically treated patients with significant coronary disease. Using detailed case summaries, five senior cardiologists each predicted one- and three-year survival and infarct-free survival probabilities for 100 patients. Fifty patients appeared in multiple samples for assessing interphysician variability. Cox regression models, developed using patients not in the test samples, predicted corresponding outcome probabilities for each test patient. Overall, model predictions correlated better with actual patient outcomes than did the doctors' predictions. For three-year survival, rank correlations were 0.61 (model) and 0.49 (doctors). For three-year infarct-free survival predictions, correlations with outcome were 0.48 (model) and 0.29 (doctors). Comparisons by individual doctor revealed Cox model three-year survival predictions were better than those of four of five doctors (model predictions added significant [p less than 0.05] prognostic information to the doctor's predictions, whereas the converse was not true). For infarct-free survival, the Cox model was superior to all five doctors. Where predictions were made by multiple doctors, the interphysician variability was substantial. In coronary artery disease, statistical models developed from carefully collected data can provide prognostic predictions that are more accurate than predictions of experienced clinicians made from detailed case summaries.

Coronary Disease↗
PubMed1985

Randomized trials of coronary artery bypass surgery: impact on clinical practice at Duke University Medical Center.

Trends in practice patterns at Duke University Medical Center were assessed in patient groups comparable to those enrolled in the three major randomized trials of coronary artery bypass grafting (CABG). In addition, changes in practice patterns that appeared unrelated to the randomized trials were examined. Most patients with 75% or greater left main stenosis have been treated surgically after publication of the Veterans Administration Cooperative Study, but little change was noted in the proportion of patients with 50% left main stenosis who have been treated surgically. A trend towards selection of surgical therapy for patients with three-vessel disease and normal left ventricular function was evident before the publication of the European Coronary Surgery Study, although one-third of patients in this category continue to be treated nonsurgically after publication of the results of the trial. For the past decade, most patients who would have been eligible for the Coronary Artery Surgery Study have been treated nonsurgically. We have also documented trends in practice patterns that are independent of the results of randomized trials. The advent of percutaneous transluminal angioplasty has provided another therapeutic alternative that has been used increasingly. In addition, growing numbers of patients with advanced age, unstable angina, or markedly depressed left ventricular ejection fraction are being evaluated with cardiac catheterization despite the lack of supporting randomized trials. Randomized trials have placed our understanding of the effects of CABG on a sound foundation, but it is evident that clinicians continue to consider many other factors when therapeutic decisions are made.

Academic Medical Centers↗
PubMed1985

Regression models for prognostic prediction: advantages, problems, and suggested solutions.

Multiple regression models have wide applicability in predicting the outcome of patients with a variety of diseases. However, many researchers are using such models without validating the necessary assumptions. All too frequently, researchers also "overfit" the data by developing models using too many predictor variables and insufficient sample sizes. Models developed in this way are unlikely to stand the test of validation on a separate patient sample. Without attempting such a validation, the researcher remains unaware that overfitting has occurred. When the ratio of the number of patients suffering endpoints to the number of potential predictors is small (say less than 10), data reduction methods are available that can greatly improve the performance of regression models. Regression models can make more accurate predictions than other methods such as stratification and recursive partitioning, when model assumptions are thoroughly examined; steps are taken (ie, choosing another model or transforming the data) when assumptions are violated; and the method of model formulation does not result in overfitting the data.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1984

"Left main equivalent" coronary artery disease: its clinical presentation and prognostic significance with nonsurgical therapy.

The clinical characteristics and nonsurgical prognosis of 55 patients with "left main (LM) equivalent" coronary artery disease (CAD) were evaluated and defined as: (1) greater than or equal to 75% diameter reduction of the left anterior descending coronary artery (LAD) before the takeoff of any large septal perforator or anterolateral (diagonal) branches; (2) greater than or equal to 75% diameter reduction of the left circumflex artery (LC) before the takeoff of any large marginal branch; and (3) absence of greater than or equal to 50% stenosis of the LM coronary artery. Compared with nonsurgically treated patients with greater than or equal to 75% stenosis of the LM artery, patients with LM equivalent CAD had a shorter duration of symptoms (median of 51 months vs 66 months) and more often had a Q wave on the electrocardiogram (60 vs 39%). Survival in patients with LM equivalent CAD (78% at 1 year and 55% at 5 years) was better than that in patients with LM disease with nonsurgical therapy (65% at 1 year and 40% at 5 years) (p = 0.02), although the rate of freedom from cardiovascular events was not significantly different. Compared with other nonsurgically treated patients with 2- or 3-vessel CAD involving the LAD and LC (28 and 42%, respectively, with progressive angina), patients with LM equivalent CAD had more severe anginal symptoms (55% with progressive angina) and a longer duration of symptoms (medians of 20 months in 2-vessel CAD, 36 months in 3-vessel CAD and 51 months in LM equivalent CAD).(ABSTRACT TRUNCATED AT 250 WORDS)

Constriction, Pathologic↗