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Biomedical subjects

R M Califf

Publications and source records attributed to R M Califf.

At least 487 records · Page 27Linked to original sources
PubMed1989

Coronary bypass surgery in chronic stable angina.

Over the last 20 years, operative mortality has decreased and late survival has improved for patients with chronic stable angina who have coronary artery bypass surgery. However, this favorable trend may not continue because the operation is now extended to elderly and high-risk patients. The most powerful predictors of operative mortality include indexes of left ventricular function, age, and the number of associated medical conditions. Female gender, severity of angina, and extent of coronary artery disease appear to be predictors of operative mortality in some series but not in all. Indexes of left ventricular dysfunction remain the most powerful predictors of late death, but the extent of coronary disease, older age, and presence of associated diseases (including noncardiac vascular disease) remain important determinants. Analyses of the randomized trials and registry studies reveal a consistent trend: in patients at high risk on the basis of clinical, functional, and anatomic characteristics, coronary artery bypass surgery prolongs survival in comparison with medical therapy alone. In patients determined to be at low risk, medical therapy is initially recommended with the realization that revascularization may be necessary subsequently if symptoms worsen or the severity of ischemia increases.

Angina Pectoris↗
PubMed1989

Clinical experience and predicting survival in coronary disease.

To study the accuracy with which long-term prognosis can be predicted in patients with coronary artery disease, prognostic predictions obtained from a large, diverse sample of practicing cardiologists were compared with predictions from a multivariable statistical model. Test samples of 10 patients each were selected from a large series of medically treated patients with significant coronary disease. Using detailed clinical summaries, 49 cardiologists each predicted the probability of 3-year survival and infarction-free survival for 10 patients. Cox regression models, developed using patients who were not in the test samples, were also used to predict corresponding outcome probabilities for each test patient. Overall, the model estimates of prognosis were significantly better than the doctors' predictions. The rank correlation of model predictions with 3-year survival was 0.60, compared with 0.52 for the physicians. Model predictions added significant prognostic information to the doctors' predictions, whereas the converse was not true. Where predictions were made by multiple doctors, the inter-physician variability was substantial. Neither practice characteristics nor extent of clinical experience significantly affected the physicians' predictive accuracy. 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↗
PubMed1988

Helicopter transport of patients during acute myocardial infarction.

Initial experience with a regional system of emergency helicopter transport of patients with acute myocardial infarction (AMI) referred for emergent cardiac catheterization and percutaneous transluminal coronary angioplasty (PTCA) is described. Two hundred fifty patients with AMI were transported from within a 150-mile radius to Duke University Medical Center over a 15-month period. All patients were within 12 hours of onset of symptoms. Thrombolytic therapy was administered to 240 (96%) patients (72% before or in-flight). The time to administration of thrombolytic therapy ranged from 30 to 120 minutes (median 180), while the time to arrival in the interventional catheterization laboratory ranged from 105 to 815 minutes (median 300). The flight time was 12 to 77 minutes (median 31). Most patients had 1- or 2-vessel coronary artery disease; the baseline ejection fraction ranged from 27 to 70% (median 42). Transient hypotension was the most common complication both pre-flight and in-flight. Third-degree atrioventricular block and nonsustained ventricular tachycardia were the next most common complications. Ventricular fibrillation or sustained ventricular tachycardia occurred before takeoff in 38 patients (15%). No patients had ventricular fibrillation, asystole or respiratory arrest during transport. Fluid boluses for hypotension were the most common intervention. Five patients required cardiopulmonary resuscitation in-flight; 3 before lift-off and 2 required a brief period of cardiopulmonary resuscitation during sustained ventricular tachycardia. Fourteen patients had pressor therapy, military antishock trousers or both to maintain adequate blood pressure. Neither cardioversion, defibrillation nor intubation were performed in-flight. Thus, inflight complications are infrequent and can be managed en route to an intervention center.(ABSTRACT TRUNCATED AT 250 WORDS)

Aircraft↗
PubMed1988

Comparison of two dose regimens of intravenous tissue plasminogen activator for acute myocardial infarction.

Two dosing schedules of intravenous tissue plasminogen activator (t-PA) for acute myocardial infarction were compared in a multicenter trial. At 2.95 +/- 1.1 hours from onset of chest pain, 386 patients received 150 mg of intravenous t-PA. For the first 178 patients (group A), 60 mg were given in the first-hour dose and the remaining 90 mg were infused over 7 hours. In the subsequent 208 patients (group B), the first-hour dose was 1.0 mg/kg and the remaining 150 mg were given over 5 hours. At initial angiography 94 +/- 30 minutes into therapy, the infarct vessel patency was 64% in group A versus 75% in group B (p = 0.02). By final angiography with up to 4 selective contrast injections, patency was 68% versus 77%, respectively (p = 0.06). Repeat angiography at 7 to 10 days demonstrated reocclusion in 17% of group A and 13% of group B patients (p = 0.35). There was no difference in fibrinogen nadir or mean hematocrit drop between the 2 groups: 120 mg/dl and 11 points, respectively, in group A compared with 120 mg/dl and 10 points in group B. However, bleeding was reduced in group B patients as evident by a decrease in requirement for greater than or equal to 2 units of packed red blood cell transfusion (group A 36%, group B 27%, p = 0.05) and lower incidence of gastrointestinal bleeding (group A 12%, group B 4%, p = 0.002). To further study the importance of weight adjustment, patients were divided into 2 groups according to weight (less than or equal to 90 kg versus greater than 90 kg).(ABSTRACT TRUNCATED AT 250 WORDS)

Angioplasty, Balloon↗
PubMed1988

Adoption of thrombolytic therapy in the management of acute myocardial infarction.

A national survey of 1,065 physicians was carried out to document current use of thrombolytic therapy for acute myocardial infarction (AMI). In early 1987, thrombolytic therapy was used by 66% of respondents. Among those who used thrombolytic therapy, 92% used streptokinase, 13% used tissue-type plasminogen activator and 3% used urokinase. Most (72%) used intravenous administration exclusively and only 5% used intracoronary administration exclusively. Despite widespread acceptance of thrombolytic therapy, most physicians gave it to less than 25% of their patients. Duration of symptoms was rated as the single most important factor affecting the decision to use thrombolytic therapy; 45% had a time limit of less than 4 hours and 85% had a time limit of less than 6 hours. Complications of AMI and electrocardiographic findings were factors also considered in the decision to give this therapy. A physician's adoption of thrombolytic therapy was significantly associated with several characteristics: specialty type, number of AMI patients treated, physician age and access to cardiac catheterization. In addition, physicians using thrombolytic therapy had a significantly different use of medications and laboratory tests for all patients with AMI. This survey documents rapid acceptance of thrombolytic therapy for AMI, particularly in patients with short duration of symptoms or evidence of high risk.

Cardiac Catheterization↗
PubMed1988

Trends in physician management of uncomplicated acute myocardial infarction, 1970 to 1987.

To document current management of uncomplicated acute myocardial infarction (AMI), a national survey of 1,065 physicians was performed. Items from previous surveys in 1970 and 1979 were included to permit analysis of time trends in management. Median hospital stay dropped from 21 days in 1970 to 9 days in 1987. Use of beta blockers and aspirin doubled between 1979 and 1987, while use of anticoagulation and sulfinpyrazone dropped 4- to 10-fold. In 1987, coronary angiography was used commonly, especially in younger patients or those with either a non-Q-wave AMI, intravenous thrombolytic therapy or a positive exercise test. These findings document the increasingly aggressive approach to the management of patients with uncomplicated AMI.

Activities of Daily Living↗
PubMed1988

Hemorrhagic complications associated with the use of intravenous tissue plasminogen activator in treatment of acute myocardial infarction.

PURPOSE: Little attention has been paid to the importance of clinical factors associated with bleeding complications caused by the use of thrombolytic agents. The goal of our study was to examine clinical and hematologic factors associated with an increased risk of bleeding in a prospectively observed population that received intravenous tissue plasminogen activator for acute myocardial infarction. PATIENTS AND METHODS: Bleeding complications were evaluated in 386 consecutive patients treated with 150 mg of tissue plasminogen activator over six to eight hours for acute myocardial infarction. All patients also underwent immediate cardiac catheterization. RESULTS: Quantitation of blood loss during the patients' hospital stay included a median drop in hematocrit of 11.4 points, a median nadir hematocrit of 31.2, a 14 percent rate of significant clinically evident bleeding, and a 31 percent rate of transfusion of two or more units of blood. All of these parameters were much more severe in patients treated with coronary artery bypass surgery. Access site hematoma was the most common source of bleeding (45 percent of patients), whereas 8 percent had gastrointestinal bleeding, two patients had retroperitoneal bleeding, and two patients had intracranial bleeding. The median nadir fibrinogen was 1.3 g/liter. Multiple linear regression models were used to investigate the relationship between clinical variables, including multiple hematologic measurements, and measures of the amount of blood loss. The use of coronary artery bypass grafting was the variable most closely associated with hemorrhage. Other invasive procedures (angioplasty and intra-aortic balloon pumping) were also associated with increased bleeding. Among the patient descriptors examined, lighter weight, older age, female sex, and history of hypertension were associated with greater blood loss. Of laboratory coagulation parameters, only nadir fibrinogen levels were significantly associated with more bleeding. CONCLUSION: Careful clinical evaluation may improve assessment of the risk/benefit ratio of thrombolytic therapy.

Age Factors↗
PubMed1988

Comparison of predictions based on observational data with the results of randomized controlled clinical trials of coronary artery bypass surgery.

Clinical decisions are most secure when based on findings from several large randomized clinical trials, but relevant randomized trial data are often unavailable. Analyses using clinical data bases might provide useful information if statistical methods can adequately correct for the lack of randomization. To test this approach, the findings of the three major randomized trials of coronary bypass surgery were compared with predictions of multivariable statistical models derived from observations in the Duke Cardiovascular Disease Databank. Clinical characteristics of patients at Duke University Medical Center who met eligibility requirements for each major randomized trial were used in the models to predict 5 year survival rates expected for medical and surgical therapy in each randomized trial. Model predictions agreed well with randomized trial results and were within the 95% confidence limits of the observed survival rates in 24 (92%) of 26 clinical subgroups. The overall correlation between predicted and observed survival rates was good (Spearman coefficient 0.73, p less than 0.0001). These results suggest that carefully performed analyses of observational data can complement the results of randomized trials.

Angina Pectoris↗
PubMed1988

Importance of clinical measures of ischemia in the prognosis of patients with documented coronary artery disease.

To examine the value of clinical measures of ischemia for stratifying prognosis, 5,886 consecutive patients who had symptomatic significant (greater than or equal to 75% stenosis) coronary artery disease were studied. Using the Cox regression model in a randomly selected half of the patients, the prognostically independent clinical variables were weighted and arranged into a simple angina score: angina score = angina course X (1 + daily angina frequency) + ST-T changes, where angina course was equal to 3 if unstable or variant angina was present, 2 if the patient's angina was progressive with nocturnal episodes, 1 if it was progressive without nocturnal symptoms and 0 if it was stable; 6 points were added for the presence of "ischemic" ST-T changes. This angina score was then validated in an independent patient sample. The score was a more powerful predictor of prognosis than was any individual anginal descriptor. Furthermore, the angina score added significant independent prognostic information to the patient's age, sex, coronary anatomy and left ventricular function. Patients with three vessel disease and a normal ventricle (n = 1,233) had a 2 year infarction-free survival rate of 90% with an angina score of 0 and a 68% survival rate with an angina score greater than or equal to 9. With an ejection fraction less than 50% and three vessel disease (n = 1,116), the corresponding infarction-free survival figures were 76 and 56%.(ABSTRACT TRUNCATED AT 250 WORDS)

Angina Pectoris↗
PubMed1988

Prognostic value of the simplified Selvester QRS score in patients with coronary artery disease.

The relation of the simplified Selvester QRS scoring system for the estimation of myocardial infarct size to survival was studied in 1,915 nonsurgically treated patients with documented coronary artery disease. Electrocardiograms (ECGs) were scored according to a simplified 29 point QRS scoring system. Using Cox model analyses, QRS scores were found to provide strong prognostic information by themselves (p less than 0.0001). Higher QRS scores were associated with lower survival rates. Patients with a score of 0 had a 1 year survival rate of 95% and a 5 year survival rate of 88%; patients with a score of 10 or more had survival rates of 81 and 52%, respectively, at the same intervals. Directly compared with the presence or absence of Q waves on the ECG, QRS scores provided greater prognostic information (p less than 0.001). When compared with 13 individual factors previously shown to provide the greatest independent prognostic information, the QRS score was the third most powerful individual prognostic factor. It did not contribute independent prognostic information in combination with the whole group, but did provide independent information in combination with the six most predictive factors. Its prognostic information overlapped mostly with clinical factors related to heart failure, and combined best with clinical factors related to the severity of ongoing myocardial ischemia. Because it is inexpensive and simple and maximizes the prognostic information from the ECG, the simplified Selvester QRS scoring system can be a useful clinical descriptor for practitioners and clinical investigators.

Cardiac Catheterization↗
PubMed1988

Survival and cardiac event rates in the first year after emergency coronary angioplasty for acute myocardial infarction.

One year survival and event-free survival rates were analyzed in 342 patients with acute myocardial infarction who were consecutively enrolled in a treatment protocol of early intravenous thrombolytic therapy followed by emergency coronary angioplasty. Ninety-four percent of the patients achieved successful reperfusion, including 4% with failed angioplasty whose perfusion was maintained by means of a reperfusion catheter before emergency bypass surgery. The procedural mortality rate was 1.2% and the total in-hospital mortality rate was 11%. Ninety-two percent of surviving nonsurgical patients who underwent repeat cardiac catheterization were discharged from the hospital with an open infarct-related artery. The related cumulative 1 year survival rate for all patients managed with this treatment strategy was 87%, and the cardiac event-free survival rate was 84%. The 1 year survival for hospital survivors was 98% and the infarct-free survival rate was 94%. Multivariable analysis identified the following factors as independent predictors of subsequent cardiovascular death: cardiogenic shock, greater age, lower ejection fraction, female gender and a closed infarct-related vessel on the initial coronary angiogram. Among patients with cardiogenic shock, despite a 42% in-hospital mortality rate, only 4% died during the first year after hospital discharge. Similarly, the in-hospital and 1 year postdischarge mortality rates were 19 and 4%, respectively, for patients with an initial ejection fraction less than 40, and 25 and 3%, respectively, for patients greater than 65 years. An aggressive treatment strategy including early thrombolytic therapy, emergency cardiac catheterization, coronary angioplasty and, when necessary, bypass surgery resulted in a high rate of infarct vessel patency.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

Insights derived from the thrombolysis and angioplasty in myocardial infarction (TAMI) trials.

In the first three phases of Thrombolysis and Angioplasty in Myocardial Infarction (TAMI) multicenter trials, 708 patients received intravenous recombinant tissue-type plasminogen activator (rt-PA) and underwent detailed assessment of clinical, angiographic and ventriculographic outcomes. The cumulative experience and data base afford the opportunity to address several important questions regarding aggressive therapy of myocardial infarction. These include predictive factors of in-hospital mortality, improvement of left ventricular function and the occurrence of recurrent ischemia. Consideration of practical issues, such as thrombolytic therapy for patients with cardiopulmonary resuscitation or previous stroke, use of coronary artery bypass surgery and the effect of operator experience on angioplasty success rate, has also been made possible. The major accomplishments as well as the deficiencies of the current approach to patient management after thrombolysis are reviewed, and the new TAMI trials currently underway are discussed.

Angioplasty, Balloon↗
PubMed1988

Administration of thrombolytic therapy in the community hospital: established principles and unresolved issues.

In patients with acute myocardial infarction presenting to community hospitals, thrombolytic therapy should be initiated as rapidly as possible under the supervision of a physician. Paramedic or nurse-initiated pre-hospital therapy is currently investigational. Each hospital must have a detailed evaluation and treatment protocol for acute myocardial infarction that specifies the timetable for patient evaluation, who should or should not receive thrombolytic therapy and the proper dose and mode of administration of the agent or agents to be used. Monitoring after the administration of thrombolytic therapy should focus on arrhythmias, hemodynamic problems, recurrent ischemia and bleeding. The role of early cardiac catheterization to detect patients who have unsuccessful thrombolysis or who require mechanical revascularization procedures is under active investigation. The design of the Thrombolysis and Angioplasty in Acute Myocardial Infarction (TAMI) 5 study, which addresses the role of acute interventional catheterization in the treatment of patients with acute myocardial infarction, is described.

Angioplasty, Balloon↗
PubMed1988

Experience with the use of tPA in the treatment of acute myocardial infarction.

Early experience with the use of tissue plasminogen activator (tPA) in acute myocardial infarction is reviewed, including comparisons with other thrombolytic agents, a summary of hemorrhagic complications associated with its use, and the rationale for adjunctive therapeutic strategies. The use of tPA has been associated with improvement in left ventricular function, a lower mortality, and a decrease in congestive heart failure signs and symptoms. A protocol for evaluation of patients with possible myocardial infarction for thrombolytic therapy is presented. Consideration must be given to other possible diagnoses, and the ECG must be evaluated carefully to ensure that appropriate criteria are met. Risk factors for hemorrhagic complications include recent trauma, surgery, gastrointestinal and genitourinary bleeding, stroke, and focal neurologic findings. Greater benefit of therapy is expected in patients with larger infarcts who have more marked ST segment changes or evidence of hemodynamic compromise, especially when they are treated early after the onset of symptoms (within the first several hours). Adjunctive measures that can be considered in the emergency department include prophylactic lidocaine, IV nitroglycerin, beta blockade, aspirin, volume replacement and monitoring for dysrhythmias, bleeding, and recurrent ischemia. A comprehensive understanding of these rapidly evolving concepts will assist the emergency physician in the evaluation and management of patients with acute myocardial infarction.

Angioplasty, Balloon↗
PubMed1988

Emergency coronary artery bypass surgery preserves global and regional left ventricular function after intravenous tissue plasminogen activator therapy for acute myocardial infarction.

Emergency coronary bypass surgery was performed in 24 (6.2%) of 386 consecutive patients enrolled in the Thrombolysis and Angioplasty in Myocardial Infarction (TAMI) Multicenter Trial. Intravenous tissue plasminogen activator was administered 2.6 +/- 0.7 h and bypass surgery was performed 7.3 +/- 1.9 h after the onset of infarction. Infarct artery patency was achieved in 21 (88%) of the 24 patients (pharmacologically in 18 or mechanically with coronary angioplasty in 3) in the catheterization laboratory before bypass surgery. The indication for surgery was left main or equivalent coronary artery disease in 7 patients, coronary anatomy unsuitable for angioplasty in 4 patients and unsuccessful coronary angioplasty in 13 patients. A coronary perfusion catheter was inserted before surgery in 11 of 13 patients with unsuccessful angioplasty. All three deaths occurred postoperatively in patients with preoperative cardiogenic shock. Three patients required surgical reexploration for postoperative hemorrhage. Comparison of preoperative and predischarge contrast left ventriculograms demonstrated significant preservation of global (left ventricular ejection fraction 49 +/- 6 to 56 +/- 6%; p = 0.008) and regional (standard deviation/chord -2.6 +/- 0.5 to -1.5 +/- 1.1; p = 0.001) left ventricular function. Emergency coronary bypass surgery can be performed with a low morbidity and mortality in patients treated with intravenous tissue plasminogen activator therapy for acute myocardial infarction. Such therapy is associated with significant preservation of global and regional (infarct zone) left ventricular function.

Adult↗
PubMed1988

Comparison of time domain and frequency domain variables from the signal-averaged electrocardiogram: a multivariable analysis.

The relative values of the unprocessed signal-averaged electrocardiogram (ECG) and time domain analysis and frequency domain analysis of the signal-averaged ECG were compared in 36 patients with sustained monomorphic ventricular tachycardia and a remote myocardial infarction, in 29 asymptomatic patients with a remote myocardial infarction and in 23 normal subjects. Area ratios of the energy spectra derived from fast Fourier transform analysis were calculated using six separate 140 ms intervals starting at 0, 40, 50 and 60 ms after QRS onset; 40 and 50 ms before QRS end and a variable length interval starting 40 ms before QRS end and extending to the T wave. Total filtered QRS duration, late potential duration and root mean square voltage of the terminal QRS complex were measured from the filtered vector magnitude signal-averaged ECG. The total QRS duration was also measured from the X, Y, Z leads of the unfiltered signal-averaged ECG. Seven variables were significantly different in univariate tests between myocardial infarction patients with and without ventricular tachycardia: three fast Fourier transform area ratios with the sampling interval starting at 1) QRS onset (p = 0.007), 2) 40 ms after QRS onset (p = 0.02), and 3) 60 ms after QRS onset (p less than 0.0001); and all four time domain variables at 1) total filtered QRS duration (p less than 0.0001), 2) late potential duration (p = 0.0001), 3) root mean square terminal QRS voltage (p = 0.0001), and 4) QRS duration from the unprocessed signal-averaged ECG (p less than 0.0001). Of these seven variables, only the fast Fourier transform area ratio starting at QRS onset was significantly different between patients with myocardial infarction without ventricular tachycardia and normal subjects. In multi-variable analysis, the total filtered vector magnitude QRS duration, a time domain variable that includes the late potential, was the only independent factor that separated patients with myocardial infarction with and without associated ventricular tachycardia.

Analysis of Variance↗
PubMed1988

Characteristics and outcome of patients in whom reperfusion with intravenous tissue-type plasminogen activator fails: results of the Thrombolysis and Angioplasty in Myocardial Infarction (TAMI) I trial.

To examine the outcome of patients with persistent coronary artery occlusion despite treatment with intravenous tissue-type plasminogen activator (t-PA), the clinical course of 96 patients with persistent occlusion after 90 min of therapy was evaluated. All patients underwent cardiac catheterization 90 min after initiation of intravenous t-PA. Immediate coronary angioplasty (PTCA) was attempted when the infarct-related artery failed to reperfuse unless the vessel was technically unsuitable or the infarct was thought to be small. No baseline differences could be found between these 96 patients and 288 patients who achieved perfusion with the same protocol. Although patients with and without successful perfusion after t-PA had similar clinical courses before cardiac catheterization, those without perfusion had more complications (ventricular fibrillation, severe bradycardia, hypotension) during catheterization. PTCA achieved reperfusion with less than 50% residual stenosis in 73% of the 86 patients in whom it was attempted, while 16% were left with a high-grade (greater than 50%) residual stenosis and PTCA failed in 11%. Mortality was highest in the nine patients with complete PTCA failure (44%), compared with a 6% mortality in the 63 patients with an insignificant residual stenosis after PTCA and a 14% mortality in the 14 patients with reperfusion, but a greater than 50% residual stenosis after PTCA. In 10 patients with small infarcts (six), unsuitable anatomy (two), or "spontaneous" drug induced (but later) opening before contemplated PTCA (two), PTCA was not attempted and no mortality occurred. The in-hospital reocclusion rate after successful PTCA was 29%, despite the use of heparin and antiplatelet agents.(ABSTRACT TRUNCATED AT 250 WORDS)

Angioplasty, Balloon↗