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A cohort of 1472 patients who underwent both exercise stress testing and coronary angiography within six weeks was examined. The data indicated that a combination of exercise parameters is both diagnostically and prognostically important. Almost all patients (greater than 97%) who had positive exercise tests at Stage I or Stage II had significant coronary artery disease. More than half of these (greater than 60%) had three vessel disease and over 25% had significant narrowing (greater than 50%) of the left main coronary artery. Patients who achieved Stage IV or greater exercise durations with either negative or indeterminate ST-segment response had less than a 15% prevalence of three vessel disease and less than a 1% prevalence of left main coronary artery disease. A low risk subgroup (75% of all non-operated patients) was identified with a twelve month survival greater than 99%. A high risk subgroup (11% of all nonoperated patients) was identified with a twelve month survival of less than 85%. The exercise test is a noninvasive, reproducible method to assess the presence and extent of anatomic disease and the prognosis when significant disease has been defined. It should be used in conjunction with other noninvasive tests to determine optimal management in patients evaluated for ischemic heart disease.

Sixty-seven consecutive patients who had suffered an acute myocardial infarction but no serious complications during the first to fourth hospital days were considered for a trial of hospital discharge at one week. Thirty-three of the 67 patients were discharged at one week, the remainder having a mean hospital stay of 11 +/- 2 days. The incidence of late complications and recurrent infarctions, as well as mortality and functional status, were determined in all patients six months after discharge. No serious complications occurred in either subgroup within three weeks after discharge. There were no deaths in either subgroup and no difference in functional status at six months. Patients without serious complications during the four days after an acute myocardial infarction can be spared the economic costs and psychologic stress of prolonged hospitalization.

A simulated randomized clinical trial in coronary artery disease was conducted to illustrate the need for clinical judgment and modern statistical methods in assessing therapeutic claims in studies of complex diseases. Clinicians should be aware of problems that occur when a patient sample is subdivided and treatment effects are assessed within multiple prognostic categories. In this example, 1073 consecutive, medically treated coronary artery disease patients from the Duke University data bank were randomized into two groups. The groups were reasonably comparable and, as expected, there was no overall difference in survival. In a subgroup of 397 patients characterized by three-vessel disease and an abnormal left ventricular contraction, however, survival of group 1 patients was significantly different from that of group 2 patients. Multivariable adjustment procedures revealed that the difference resulted from the combined effect of small imbalances in the distribution of several prognostic factors. Another subgroup was identified in which a significant survival difference was not explained by multivariable methods. These are not unlikely examples in trials of a complex disease. Clinicians must exercise careful judgment in attributing such results to an efficacious therapy, as they may be due to chance or to inadequate baseline comparability of the groups.

Summary This analysis attempts to utilize natural history controls to answer the question as to whether coronary surgery prolongs life in comparison to medical management. Selected natural history studies are compared and contrasted in an effort to obtain an average survival curve for patients with coronary artery disease comparable to those presently being operated. The Duke University Medical Center series of concurrent operated and non-operated patients is reviewed to demonstrate the difference of prognosis of patients with coronary artery disease and the complexities involved in answering the question. It is concluded that, on average, coronary surgery does not prolong life in comparison to medical management over the span of 2-5 years. There may be certain higher risk patients whose lives may be prolonged by aortocoronary bypass surgery but more patients and more prolonged follow-up are needed fully to answer the question.

This report represents our experience with 522 consecutive patients with acute myocardial infarction admitted directly to the Duke Coronary Care Unit. Fifty items of information were used to characterize the patients, their hospital course and follow-up. Serious complications included death, ventricular tachycardia or fibrillation, second- or third-degree heart block, pulmonary edema, cardiogenic shock, persistent sinus tachycardia or hypotension, atrial flutter or fibrillation, and extension of infarction. Forty-nine percent of the patients (252 of 522) experienced a serious complication. All patients who experienced any serious complications had at least one of the above during the first four days of hospitalization. Patients who survived through day 4 were subgrouped on the basis of the occurrence (complicated) or lack of occurrence (uncomplicated) of the above on day 5. Complicated patients had a subsequent hospital mortality of 14% and an incidence of late serious complications of 51%. Patients who were uncomplicated through day 4 had a subsequent hospital mortality of zero and an incidence of late serious complications of zero. These data suggest that it would be feasible and ethically justified to conduct a prospective clinical trial of early discharge (7th day) in patients who meet the above criteria for uncomplicated. The potential economic savings through earlier discharge in uncomplicated patients are of major significance.

The effect of four frequency functions was evaluated with respect to a decision rule used to select treatment in patients with coronary artery disease. Of the four functions tested, it was found that the multinomial and product functions provided an estimated improvement in treatment selection over current clinical decision procedures. The linear and quadratic provided no improvement. In chronic disease, where the time between intervention and response is long, the computer can be used to store patient descriptors, their treatment, and long-term responses. Using these data, decision rules can be constructed for prospective treatment selection. The effectiveness of the multinomial and product models illustrates the applicability of such an approach to treatment selection in chronic disease.

Three-year survival for 163 consecutive medically treated patients with 50% or greater left main stenosis was 50%. Survival was significantly higher for patients with 50 to 70% left main stenosis (one and three-year survivals of 91% and 66%) than for patients with 70% or greater left main stenosis (one and three-year survivals of 72% and 41%). In fact, left main lesions of less than 70% were not associated with the increased risk usually attributed to patients with left main stenosis. A number of noninvasive and catheterization characteristics were significant predictors of survival for patients with 70% or greater left main stenosis. Noninvasive descriptors defined a low risk subgroup (one and three-year survivals of 97% and 74%) and a high risk subgroup (one- and three-year survivals of 59% and 25%). These observations have important implications both in assessing therapeutic interventions and in managing individual patients.

A data bank containing our clinical experience with more than 3,000 patients with suspected and documented ischemic heart disease is being used to expand our ability to care for patients. This report describes how the experience is documented, stored, and retrieved so that it can be used in patient management. Data acquisition is integrated with patient care by means of forms that are part of the patient record. Follow-up information is obtained at six months, one year, and yearly thereafter. All data are stored in a computer information system that allows the doctor to recall the experience of patients like his new patient. Prognostic information is available on each new patient both on-line and in the form of a printed laboratory report. The data bank represents an initial chapter of a computer textbook of medicine.