Background: Technetium-labeled myocardial perfusion tracers allow simultaneous assessment of myocardial perfusion and left ventricular function by electrocardiography (ECG)-gated myocardial single photon emission computed tomography (SPECT). The purpose of this study was to evaluate left ventricular performance during dobutamine stress by means of ECG-gated myocardial perfusion SPECT with short-time data collection.
Methods and results: After administration of Tc-99m sestamibi or tetrofosmin (600-740 MBq), 67 patients with ischemic heart disease, including 35 with prior myocardial infarction, were examined by ECG-gated myocardial perfusion SPECT at rest and during dobutamine stress (at dosages of 4, 8, 12, 16, and 20 microg/kg/min, with increments every 8 minutes). The ECG-gated data collection time was 5 minutes for each dobutamine dosage. After acquisition of gated SPECT data at the highest dose, thallium 201 chloride (111 MBq) was injected, and dual-isotope SPECT was also performed to assess the myocardial ischemia. In 32 patients without prior myocardial infarction, the sensitivity of individual stenosed-vessel detection with dual-isotope perfusion SPECT, with wall motion abnormality obtained from gated SPECT, and with the combined method was 55.9%, 52.9%, and 73.5%, respectively, based on coronary angiography. ECG-gated SPECT during dobutamine infusion revealed regional wall motion abnormalities (worsening or biphasic response) in 19 (57.6%) of 33 infarcted areas with culprit coronary arterial stenosis. The prevalence of reversible perfusion defects on dual-isotope SPECT was higher in segments with wall motion abnormalities than in segments with normal wall motion response (89.5% vs 42.9%, P <.02).
Conclusions: Myocardial perfusion and left ventricular function during dobutamine infusion were analyzed in a single examination by means of the combined method. This procedure has the potential to provide comprehensive information with which to evaluate patients with ischemic heart disease.