Abstract
The purpose of the present study was to evaluate the feasibility of gated blood pool single-photon emission computed tomography (GBPS) with low-dose dobutamine (LDD) stress test, performed on a single-photon emission computed tomography (SPECT) camera equipped with cadmium-zinc-telluride (CZT) solid-state detectors, in assessing of left ventricle (LV) contractile reserve in patients with ischemic cardiomyopathy (ICM). A total of 52 patients (age 59 ± 7.2years, 47 men and 5 women) with 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, 15µg/kg/min). The duration of each GBPS step was 5min. Stress-induced changes in LV ejection fraction (ΔLVEF), peak ejection rate, LV volumes, and mechanical dyssynchrony (phase histogram standard deviation, phase histogram bandwidth and entropy) obtained with GBPS were estimated. All GBPS indices except end-diastolic volume showed significant dynamics during stress test in both groups. The majority of parameters in ICM patients showed significant changes at a dobutamine dose of 10µg/kg/min as compared to the rest study. Seventeen percent of ICM patients, but none from the control group, showed a decrease in LVEF during stress, accompanied by a significant increase in entropy. The intra- and inter-observer 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. Low-dose dobutamine stress GBPS performed with high-efficiency CZT-SPECT cameras can be performed for evaluating stress-induced changes in LV contractility and dyssynchrony with lower acquisition time. A dobutamine dose of 10µg/kg/min can potentially suffice to detect stress-induced changes in patients with ICM during GBPS. ClinicalTrials.gov identifier: NCT04508608 (August 7, 2020).
Highlights
Equilibrium radionuclide angiography (ERNA) is a well-established imaging modality for the assessment of cardiac function due to its high accuracy and reproducibility [1]
Low-dose dobutamine stress gated blood pool SPECT performed with high-efficiency CZTSPECT cameras allow evaluation of stress-induced changes in LV contractility and dyssynchrony in patients with ischemic heart failure (HF)
Inclusion criteria for ischemic cardiomyopathy (ICM) patients were: reduced LV systolic function with an EF < 40% and an increase in LV volumes demonstrated by transthoracic echocardiography (TTE), history of myocardial infarction or revascularization, > 75% stenosis of left main or > 75% stenosis in the proximal left anterior descending artery, and/ or stenosis of > 75% of two or more epicardial vessels based on invasive coronary angiography results [9]
Summary
Equilibrium radionuclide angiography (ERNA) is a well-established imaging modality for the assessment of cardiac function due to its high accuracy and reproducibility [1]. Data are lacking regarding the use of ERNA with inotropic pharmacological stress tests. Published articles have demonstrated the prognostic value of planar stress ERNA and have shown that it may be used as an alternative to exercise testing for risk stratification [2, 3, 4]. Saliman S. et al have described stress gated blood pool SPECT (GBPS) in an experimental study on canine models [5]. The study duration was of approximately 140 min, which is inappropriate for clinical practice. Introduction of gamma cameras with solid-state semiconductor cadmium zinc telluride (CZT) detectors allows to significantly shorten the imaging time [6, 7, 8], an important feature which could be implemented in GBPS
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