Guidelines for clinical use of cardiac radionuclide imaging report of the American College of Cardiology/American Heart Association Task Force on Assessment of Diagnostic and Therapeutic Cardiovascular Procedures (Committee on Radionuclide Imaging), developed in collaboration with the American Society of Nuclear Cardiology

New England Journal of Medicine, 327(10), 685-691

To assess visual interpretation of the coronary arteriogram as a means of predicting the physiologic effects of coronary obstructions in human beings, we compared caliper measurements of the degree of coronary stenosis with the reactive hyperemic response of coronary flow velocity studied with a Doppler technique at operation, after 20 seconds of coronary arterial occlusion. In 39 patients (44 vessels) with isolated, discrete coronary lesions varying in severity from 10 to 95 per cent stenosis, measurement of the percentage of stenosis from coronary angiograms was not significantly correlated (r = -0.25) with the reactive hyperemic response. Results were the same for obstructions in the left anterior descending, diagonal, and right coronary arteries. Underestimation of lesion severity occurred in 95 per cent of vessels with greater than 60 per cent stenosis of the diameter by arteriography. Both overestimation and underestimation of lesions with less than 60 per cent stenosis were common. These results, together with the high interobserver and intraobserver variability of standard visual analysis of angiograms, suggest that the physiologic effects of the majority of coronary obstructions cannot be determined accurately by conventional angiographic approaches. The need for improved analytical methods for the physiologic assessment of angiographically detected coronary obstructions is apparent.

Many asymptomatic patients with aorta regurgitation and normal left ventricular systolic function remain clinically stable for many years, but others ultimately develop symptoms or left ventricular dysfunction and require operation. To identify indexes of left ventricular function predictive of symptomatic and functional deterioration during the long-term course of asymptomatic patients, we studied 104 asymptomatic patients with chronic severe aortic regurgitation and normal left ventricular ejection fraction at rest. Serial echocardiographic (average, 7.8 per patient) and radionuclide angiographic (average, 5.0 per patient) studies were obtained over a mean follow-up period of 8 years (range, 2-16 years). By Kaplan-Meier life table analysis, 58 +/- 9% of patients remained asymptomatic with normal ejection fraction at 11 years, an average attrition rate of less than 5% per year; two patients died suddenly, four developed asymptomatic left ventricular dysfunction, and 19 underwent operation because symptoms developed. By univariate Cox regression analysis, many variables on initial study were associated with death, ventricular dysfunction, or symptoms, including age, left ventricular end-systolic dimension and end-diastolic dimension, fractional shortening, and both rest and exercise ejection fraction (all p less than 0.001). The average rates of change of rest ejection fraction, fractional shortening, and end-systolic dimension were also associated with death or symptoms by univariate Cox analysis (all p less than 0.01). However, when all variables were included in a multivariate Cox analysis, only age (p less than 0.05), initial end-systolic dimension (p less than 0.001), and rate of change in end-systolic dimension and rest ejection fraction during serial studies (both p less than 0.05) predicted outcome. Thus, in addition to indexes of left ventricular function determined on initial evaluation, serial long-term changes in systolic function identify patients likely to develop symptoms and require operation. Patients have a higher risk of symptomatic deterioration if there is progressive change in end-systolic dimension or resting ejection fraction during the course of serial studies.