Radionuclide absolute left ventricular volumes during upright exercise: validation in normal subjects by simultaneous hemodynamic measurements.

A nongeometric radionuclide technique for the determination of absolute left ventricular volumes was validated during exercise in nine normal subjects. Simultaneous reference stroke volume and cardiac output measurements were obtained by the Fick method. The reference left ventricular volumes were calculated by combining the Fick stroke volume and the isotopic ejection fraction. Data were collected at rest in the supine and upright positions and during 60 degrees upright exercise, at three levels of increasing severity. At rest, from supine to upright position, the reference end-diastolic volume decreased significantly from 182 +/- 24 ml to 154 +/- 21 ml (mean +/- SD, P less than 0.005); during upright exercise of low intensity, end-diastolic volume increased to 176 +/- 24 ml (P less than 0.05); at maximal exercise, end-diastolic volume was not different from the resting value in upright position. The end-systolic volume gradually decreased at rest from 67 +/- 11 ml in the supine position to 54 +/- 8 ml in the upright position (P less than 0.05). Compared with these reference data, the scintigraphic measurements were significantly lower on average by 23% for stroke volume, 21% for cardiac output, 22% for end-diastolic volume, and 23% for end-systolic volume. The overall changes in stroke volume (P less than 0.05) and end-systolic volume (P less than 0.001) occurring at rest and during exercise were correctly detected by the scintigraphic method but the smaller changes in end-diastolic volume (less than 15%) were not (P less than 0.15) because they were within the range of the precision of the technique.(ABSTRACT TRUNCATED AT 250 WORDS)

Bayesian analysis of stress thallium scintigraphy for the detection of multivessel coronary disease.

This study was performed in 224 men to determine the respective contribution of history and thallium-201 stress myocardial scintigraphic imaging in the non-invasive prediction of the severity of coronary disease. Myocardial scintigraphic imaging had the better diagnostic accuracy (80%) for the detection of multivessel disease but the results emphasize the importance of the history in predicting the extent of coronary artery disease. In patients with myocardial infarction, the diagnostic accuracy of the history (80%) was similar to the diagnostic accuracy of myocardial scintigraphic imaging (79%); in the subgroup of patients with residual angina pectoris after infarction, the accuracy of the history was even greater (87%) than that of myocardial scintigraphic imaging (78%). Thus, after myocardial infarction, scintigraphy was useful only in the small subgroup of patients without residual angina pectoris when it had a diagnostic accuracy of 79%, slightly but insignificantly superior to that of the history (62%). In patients without previous myocardial infarction, but with typical angina, myocardial scintigraphy was clearly superior to the simple history (diagnostic accuracy of 78% versus 53%; P less than 0.001). In patients without myocardial infarction and with atypical angina the prevalence of multivessel disease was low (17%) and the diagnostic accuracy of history (83%) was barely different from the diagnostic accuracy of myocardial scintigraphic imaging (90%). Thus, when the likelihood of multivessel disease is very high (angina pectoris post myocardial infarction), or very low (atypical angina), the contribution of exercise testing is very limited. Important additional information is provided by maximal exercise testing and myocardial scintigraphic imaging only in the groups with an intermediate prevalence of multivessel disease, namely in the asymptomatic patients after myocardial infarction and in the patients with typical angina but no previous myocardial infarction.