Gated blood pool scintigraphic monitoring of doxorubicin cardiomyopathy: Comparison of camera and computerized probe results in 101 patients

Serial gated blood pool scintigraphic monitoring of cardiac function with both a nonimaging scintillation probe and a conventional gamma camera-computer imaging system was performed in 101 patients receiving doxorubicin hydrochloride (Adriamycin) chemotherapy. Comparision of probe- and camera-derived ejection fractions (n = 287) correlated significantly (r = 0.70, p < 0.005) as did the interstudy (n = 183) change in ejection fraction (r = 0.76, p > 0.005). Significant discordance in probe- and camera-derived ejection fraction change occurred in 3 (1.6%) of 183 interstudy intervals. Average intrastudy variability of absolute probe-derived ejection fraction was 2.9%. This variability was unrelated to the level of cardiac function. Thirteen patients (13%) developed clinical cardio-toxicity, including four at cumulative Adriamycin levels less than 450 mg/m². Mean absolute camera ejection fraction decline for these patients was 21 % from baseline evaluation, and mean absolute probe ejection fraction decline was 22%. The minimal absolute ejection fraction decline was 11% for patients with clinical congestive heart failure. Eight asymptomatic patients had therapy terminated before the development of clinical cardio-toxicity after a mean decline in absolute camera ejection fraction of 19 ± 4% (SD) and in probe ejection fraction of 19 ± 9% into abnormal ranges (a decline in magnitude equivalent to that in patients developing congestive failure). None of these five asymptomatic patients available for clinical follow-up at 6 months after termination of Adriamycin therapy subsequently developed signs of ventricular dysfunction. The majority of patients (83%) studied at 450 mg/m2 cumulative dose levels did not have a 15% or greater decline from baseline into the abnormal range. Thus, variability of a probe-derived ejection fraction measurement was similar to that derived from a conventional camera system and was within acceptable limits for characterization of clinical Adriamycin cardio-toxicity. The probe provides a less expensive alternative method for monitoring of Adriamycin toxicity with similar reliability to the more elaborate camera-computer system.