Patients with coronary artery disease, left ventricular dysfunction, and asymptomatic, unsustained ventricular tachycardia in whom sustained ventricular tachyarrhythmias cannot be induced have a significantly lower risk of sudden death or cardiac arrest and lower overall mortality than similar patients with inducible sustained tachyarrhythmias.

SUMMARY In this study we describe the ejection fraction response to upright exercise using first-pass radionuclide angiocardiography in a group of 60 patients with chest pain, normal coronary arteriograms and normal resting ventricular function. A wide range of resting function (heart rate and ejection fraction) and exercise function (heart rate, ejection fraction, peak work load and estimated peak oxygen uptake) were measured. The ejection fraction response to exercise demonstrated wide variation, ranging from a decrease of 23% to an increase of 24%. Six of 22 clinical and radionuclide angiocardiographic variables (resting ejection fraction, peak work load, age, sex, body surface area and the change in end-diastolic volume index with exercise) were significant univariate predictors of the ejection fraction response to exercise. Multivariable analysis identified resting ejection fraction, the change in end-diastolic volume index with exercise and either sex or peak work load as variables that provided significant independent predictive information. These observations indicate that the ejection fraction response to exercise is a complex response that is influenced by multiple physiologic variables. The wide variation in this population suggests that the ejection fraction response to exercise is not a reliable test for the diagnosis of coronary artery disease because of its low specificity.GATED EQUILIBRIUM and first-pass radionuclide angiocardiography (RNA) have been validated as accurate, noninvasive methods for measuring ejection fraction (EF).1--Using either technique, the changes in EF with exercise have been reported to be useful in the diagnosis of coronary artery disease.4 5 However, these studies have reported observations in only a small number of patients with chest pain and normal coronary arteriograms.4 6 The normal, healthy subjects that have been used for additional comparison to patients with coronary artery disease may not be representative in terms of age, sex or physical conditioning of the population in whom the noninvasive diagnosis of coronary artery disease is sought. The purpose of this study is to report our experience with upright rest and exercise first-pass RNA in a group of 60 patients with chest pain, normal coronary arteriograms and normal resting ventricular function and to identify factors other than coronary artery disease that influenced the EF response to exercise in this population. In patients under treatment with propranolol, the drug was generally tapered and discontinued 24 hours before the RNA study. However, eight patients (six females and two males) had taken propranolol within 24 hours of the study because of the severity of their symptoms. Study AcquisitionAll studies were performed with the patient sitting. A modified V5 electrocardiographic lead was monitored throughout and used to measure heart rate. Blood pressure was measured indirectly with a

SUMMARY We studied the ejection fraction (EF) response to upright exercise using first-pass radionuclide angiography (RNA) in 281 patients with chest pain, significant coronary artery disease and normal resting ventricular function. A wide range of resting function (heart rate and EF) and exercise function (heart rate, EF and peak work load) was measured in this population. The EF response to exercise (AEF) varied widely, ranging from a decrease of 36% to an increase of 26%. Twenty-eight clinical, catheterization and RNA variables were examined to determine their relationship to AEF. Considered individually, the variables showing the strongest relationship were resting pulse pressure, positive exercise ECG changes and adequate exercise. Multivariable analysis identified resting pulse pressure, adequate exercise, resting EF, the change in end-diastolic volume index with exercise, positive exercise ECG changes and, to a lesser degree, the number of diseased vessels as variables that were significant independent predictors of l\EF. These observations indicate that AEF is a complex response that is influenced by many pathophysiologic variables in the presence of coronary artery disease. Several of these variables are not related to the extent of coronary artery disease.

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