REST AND TREADMILL EXERCISE FIRST-PASS RADIONUCLIDE VENTRICULOGRAPHY - VALIDATION OF LEFT-VENTRICULAR EJECTION FRACTION MEASUREMENTS

Background. To assess the accuracy of rest and treadmill exercise first-pass radionuclide ventriculographic measurements of left ventricular ejection fraction (LVEF), 40 patients underwent treadmill exercise first-pass and bicycle exercise equilibrium radionuclide ventriculography. To determine the frequency of technically adequate treadmill exercise first-pass studies, an additional 128 consecutive patients undergoing treadmill exercise first-pass procedures during stress Tc-99m-labeled sestamibi myocardial perfusion studies were assessed. Methods and Results. The treadmill exercise first-pass procedure used a multicrystal camera and an Am-241 point source to allow for correction of patient motion. Excellent correlations were observed between resting first-pass and resting equilibrium LVEF (r = 0.91; standard error of the estimate = 5.6). A high correlation was also observed between treadmill exercise first-pass and bicycle equilibrium exercise LVEF measurements (r = 0.85, standard error of the estimate = 7.6). Treadmill first-pass LVEF systematically underestimated the bicycle equilibrium LVEF. Intraobserver agreement for rest and exercise first-pass LVEF was high (r values of 0.98 and 0.91, respectively). Of the 168 consecutive treadmill exercise first-pass studies evaluated for technical adequacy, 21 (12.5%) were deemed technically inadequate, with most of the sources of error being avoidable. The frequency of technically adequate studies was as high (87%) in high levels of exercise (Bruce stages 3 and 4) as in lower levels (88%). The findings of this study validate the first-pass treadmill exercise LVEF measurement. Conclusion. This procedure now provides the option for combining the information of peak treadmill exercise LVEF with measurements of exercise myocardial perfusion from the same injection of radioactivity.