The possible role of nuclear imaging in assessment of the cardiac resynchronization therapy effectiveness in patients with moderate heart failure

Background: The aim of the study was to elucidate the role of nuclear medicine imaging in the selection of candidates for cardiac resynchronization therapy (CRT) and in the evaluation of CRT effectiveness Methods: We studied 28 patients (19 male and 9 female) with dilated cardiomyopathy (DCM) and heart failure (HF). Before implantation of CRT device, all patients underwent SPECT with ^99mTc-MIBI at rest to evaluate the myocardial perfusion, ¹²³I-BMIPP to evaluate the myocardial metabolism, and gated cardiac blood-pool SPECT (GBPS) to assess the myocardial contractile function. Following CRT, all patients were examined with 99mTc-MIBI SPECT and GBPS 12 ± 3 months after the intervention. Results: All patients after CRT were divided into three groups. The first group included 10 patients with LVEF increased by more than 10 % (hyperresponders), the 2nd group included 11 patients with an increase in EF of more than 5 % but less than 10 % (responders) and third group consisted of 7 males whose LVEF remained unchanged or worsened compared with pre-operative values (nonresponders). Prior to CRT, no statistically significant differences were found between groups in hemodynamic parameters (EF, EDV, ESV, SV), intra- and interventricular dyssynchrony, as well as in the midsize of perfusion defects. Following long-term CRT, we found increase in LVEF and decrease in average size of perfusion defects in groups of hyperresponders and responders (p < 0.05). Results of SPECT with ¹²³I-BMIPP, performed prior to CRT, showed that nonresponders had more pronounced disturbance of myocardial metabolism compared with the group of hyperresponders (20 vs. 14.7 %, p < 0.05). Conclusion: The radionuclide methods can be used as possible indicators in the evaluation effectiveness and selection of candidates on the CRT.