Abstract
Cardiac resynchronization therapy (CRT) has been utilized for patients with advanced heart failure since 2004 in Japan. However, it has been regarded as the problem that about 30% of the patients with CRT show poor functional improvement. For the prediction of CRT response, the importance of the quantitative assessment of left ventricular (LV) dyssynchrony has been reported. Therefore, we developed novel algorithm for quantitative assessment of LV dyssynchrony with radionuclide imaging; ECG-gated myocardial perfusion SPECT imaging (NCVC method).
We applied “partial volume effect” in SPECT system for detecting regional systolic timing. Measuring the sequential change of regional myocardial counts in cardiac cycle, we determined “time to end-systole (TES)” which was the time from R-wave to maximum counts phase in each region. Then, we calculated maximum difference of TES between regions, named as “Dissynchrony Index (DI).”
For the verification of this NCVC methods, we evaluated the patients with CRT implantation. Responders showed significantly higher DI than non-responder, and also showed significant reduction of DI after CRT, however, non-responder did not show such reduction. Moreover, DI showed significant correlation to the index of LV dyssyncrhony evaluated by “phase analysis” of commercially available software: QGS (quantitative gated SPECT). From these results, our novel algorithm “NCVC method” might be useful for CRT management; such as decision of indication and evaluation of therapeutic response similar with other software.
