Low-dose Dobutamine Stress Gated Blood Pool SPECT Assessment of Left Ventricular Contractile Reserve in Ischemic Cardiomyopathy: a Feasibility Study

Purpose: The purpose of present study was to assess the feasibility of GBPS with low-dose dobutamine (LDD) stress test, performed on a SPECT camera equipped with Cadmium-Zinc-Telluride (CZT) solid state detectors in evaluation of patients with ischemic heart failure (HF). Methods. A total of 52 patients with ischemic cardiomyopathy (ICM) and a control group of 10 patients without obstructive coronary artery lesion underwent GBPS and transthoracic echocardiography (TTE) at rest and during LDD stress test (5, 10, 15 µg/kg/min). The duration of each GBPS step was 5 minutes. Stress-induced changes (∆) in LV ejection fraction (LVEF), peak ejection rate, LV volumes and dyssynchrony (phase histogram standard deviation, phase histogram bandwidth and entropy) obtained with GBPS were estimated. Results. All GBPS indices except end-diastolic volume showed significant dynamics during stress test in both groups. 17% of ICM patients, but none from control group, showed a decrease in EF during stress, accompanied by a significant increase in entropy. The inter-rater reproducibility was excellent for both rest and stress studies. There was a moderate correlation (r=0.5, p=0.01) between GBPS and TTE, with a mean difference value of -1.7 (95% confidence interval -9.8; 6.4; p=0.06) in ΔLVEF. Conclusion. Low-dose dobutamine stress gated blood pool SPECT performed with high-efficiency CZT-SPECT cameras allow evaluation of stress-induced changes in LV contractility and dyssynchrony in patients with ischemic HF. The high sensitivity of the semiconductor detectors provides an opportunity to perform GBPS with lower acquisition time and a decrease in patient radiation exposure. ClinicalTrials.gov identifier: NCT04508608 (August 7, 2020)