Low-dose dobutamine nitrate-enhanced technetium 99m sestamibi gated SPECT versus low-dose dobutamine echocardiography for detecting reversible dysfunction in ischemic cardiomyopathy

Abstract

Background. The simultaneous assessment of perfusion and function with the use of technetium 99m sestamibi gated single photon emission computed tomography (SPECT) is helpful for the detection of myocardial viability, but its value in comparison with more established methods is not yet defined.Methods and Results. This study compared low-dose dobutamine (LDD) nitrate-enhanced gated SPECT with LDD echocardiography for predicting recovery of regional ventricular function after revascularization in 25 patients with ischemic cardiomyopathy. In both studies, regional function (wall motion and thickening) at rest, during inotropic stimulation, and after revascularization was scored by a 4-point scale. In LDD echocardiography, the prediction of reversible dysfunction was based on the recognition of contractile reserve in asynergic (hypokinetic or a-dyskinetic) segments. In LDD gated sestamibi SPECT, reversible dysfunction was predicted on the basis of perfusion quantification (sestamibi uptake > 50%) in a-dyskinetic segments and on the basis of contractile reserve in hypokinetic segments. LDD echocardiography predicted reversible dysfunction with sensitivity, specificity, and global accuracy of 57%, 85%, and 75%, respectively. The sensitivity and specificity of LDD gated SPECT for identifying dysfunctional segments capable of functional recovery were 77% and 88%, respectively, with a diagnostic accuracy of 84% (P < .02 vs LDD echocardiography).Conclusions. The combined use of 2 different markers of viability, such as cellular integrity in a-dyskinetic segments and contractile reserve in hypokinetic segments, as permitted by LDD gated sestamibi SPECT, showed higher predictive accuracy for reversible dysfunction than the assessment of contractile reserve in all asynergic segments with LDD echocardiography. (

Single Tc99m Sestamibi injection, double acquisition gated SPECT after stress and during low-dose dobutamine infusion: a new suggested protocol for evaluation of myocardial perfusion

“…Considering that viable myocardium may functionally improve in response to inotropic stimulation and contractile reserve elicited by LDD is a predictor of functional recovery in patients with chronic CAD [22], the above-mentioned dilemma is expected to be overcome using constant infusion of LDD during another session of image acquisition. With the same logical basis, LDD infusion was added to the routine procedures of echocardiography and rest gated SPECT, and it has been shown to result in higher diagnostic and prognostic value in patients with CAD [15,23]. In fact, our study confirmed that SIDAGS-LDD is superior to the gated stress-only protocol in detecting more reversibility in patients with previous MI.…”

“…Although, we found no identical study which has compared stress-phase gated images before and after LDD infusion for CAD diagnosis and viability assessment, some studies have used LDD infusion only during the rest phase imaging to improve test value in detection of the viable tissue. Leoncini et al [15] showed higher predictive accuracy for reversible dysfunction using LDD infusion at rest phase gated SPECT than with LDD echocardiography. Also the value of rest phase gated SPECT during LDD infusion plus nitrate for detection of more viability in hibernated myocardium has been reported by Entok et al [16].…”

Single Photon Emission Computed Tomography (SPECT) Myocardial Perfusion Imaging Guidelines: Instrumentation, Acquisition, Processing, and Interpretation

“…Redistribution of 201 Tl on 4-hour and 24-hour redistribution images in myocardial segments with severely reduced tracer uptake on rest 201 Tl images indicates viability. 143 Hypoperfused myocardial segments with unequivocal improvement following nitrate administration 139 or contractile reserve on low-dose dobutamine 140 are viable. When performing 201 Tl stress-redistribution-reinjection protocols or 99m Tc MPI protocols, it is encouraged to administer 0.4 to 0.8 mg sublingual nitroglycerin prior to reinjection to optimize identification of ischemic viable myocardium.…”

“…At present, there is no consensus regarding the acquisition protocol needed for SPECT MBF. Similar to PET protocols for MBF, 140 the initial temporal sampling of the dynamic series should be rapid (3 to 10 seconds) to allow an accurate image-based measurement of the arterial input function (AIF). Acquisition should begin immediately before injection to ensure that the entire AIF is captured.…”

“…Myocardial viability can be determined using SPECT ( 99m Tc and 39 In addition, evaluation of stress perfusion (ischemia implies viability), nitrate enhanced perfusion, 139 inotropic contractile reserve with changes in regional/global function with low-dose dobutamine 140 are important adjuncts to enhance the detection of myocardial viability. When available myocardial metabolic imaging with 18 F-FDG is a more sensitive means to detect viability.…”