P3346Dynamic single photon emission computer tomography in assessment of myocardial flow reserve in patients with coronary artery disease

Abstract

Background: Coronary artery disease is currently number one cause of morbidity and mortality from cardiovascular diseases. According to the ESC recommendations, 50-90% coronary artery stenosis requires surgical restoration of blood flow only in case of verified ischemia which can be confirmed by determining FFR. Single-photon emission computed tomography (SPECT) plays an important role in diagnosing ischemia of the myocardium with high values of sensitivity and specificity. Purpose(s): The purpose of this study was to assess the myocardial flow reserve in patients with MVCAD by dynamic SPECT using semiconductor (cadmium-zinctelluride)- based gamma camera. Material(s) and Method(s): The study comprised 22patients (15 males and 7 females; mean age of 60.7+/-10.5 years) with MVCAD with the presence of coronary artery stenosis greater than 70% according to CAG. Control group consisted of 7 men and 3 women (26+/-5 years) without any cardiac diseases (healthy volunteers). All patients and volunteers underwent myocardial SPECT using semiconductor (cadmium-zinc-telluride)-based gamma camera. We used 99mTc-MIBI as a radiopharmaceutical. Acquisition protocol was as follows: (1) rest radiopharmaceutical injection (volume of 1 mL; dose of 185 MBq); 5-min list-mode acquisition; (2) stress radiopharmaceutical injection (volume of 1 mL; dose of 740 MBq) followed by four-adenosine injection protocol (160 mcg/kg/min). List-mode (5-min duration) was started simultaneously with the injection of the radiopharmaceutical. All scintigraphic images were acquired with the hybrid SPECT/CT unit (GE Discovery NM/CT 570C). To assess myocardial flow reserve, we calculated the ratio of mean counts from the left ventricular myocardial region to the area under the curve from the left ventricular cavity. The index of myocardial blood flow reserve was calculated by dividing the ratio acquired in stress test by the ratio obtained at rest. Result(s): The average value of the global myocardial flow reserve (gMFR) index was lower in a MVCAD group. The gMFR indexes were 1.41+/-0.48 versus 1.88+/-0.43 in patients with three-vessel coronary artery disease and healthy volunteers, respectively (p<0.05). Regional myocardial blood flow reserve (rMFR) indexes also significantly (p<0.05) differed between patients with MVCAD and control group: 1.34+/-0.43 versus 1.88+/-0.38 for the apex; 1.44+/-0.41 versus 1.95+/-0.45 for the lateral wall; 1.32+/-0.44 versus 1.63+/-0.43 for the anterior wall; and 1.44+/-0.77 versus 2.06+/-0.38 for the septal wall, respectively. ROC analysis showed that the gMFR = 1.77 allowed for identifying MVCAD with the sensitivity and specificity rates of 81.8% and 66.7%, respectively. Conclusion(s): Dynamic myocardial rest-stress SPECT using semiconductor (cadmium-zinc-telluride)-based gamma camera allowed for identifying low myocardial flow reserve in patients with MVCAD. This approach can be helpful in assessment of the severity of myocardial perfusion abnormalities in these patients.