Abstract 3026: Usefulness of Quantitative Gated Myocardial Perfusion SPECT to Evaluate the Initial Effectiveness of Cardiac Resynchronization Therapy and to Predict Left Ventricular Reverse Remodeling
Background: Quantitative gated myocardial perfusion SPECT (QGS) is widely used to evaluate left ventricular (LV) volume and regional wall thickening (WT). In this study, we examined whether QGS is useful to evaluate the initial efficacy of cardiac resynchronization therapy (CRT) and to predict LV reverse remodeling.
Methods: Twenty-three patients with chronic heart failure due to systolic LV dysfunction underwent 16-interval ECG-gated SPECT with 99mTc-sestamibi before (pre) and 2 weeks after (post) CRT. The commercially available QGS software was used to determine LV end-diastolic (EDV) and end-systolic volume (ESV), ejection fraction (EF), and regional WT scores in 8 LV circumferential segments except the apex (each 2 segments from the anterior, lateral, inferior and septal regions of LV). Follow-up QGS was performed at 6 months after CRT in 15 patients to identify CRT responders who showed reverse remodeling (>10% decrease in ESV).
Results: CRT effectively improved the NYHA class (−1.0±0.1, mean±SE, P<0.001) and plasma BNP levels at hospital discharge (−276±89 pg/ml, P<0.01). After the initial 2 weeks with CRT, non-uniform WT as represented by the coefficient of variation of regional WT scores (CVWT) among the 8 LV segments was significantly reduced (pre: 0.54±0.05 vs. post: 0.42±0.04, P<0.05). Furthermore, the ratio of septal-to-lateral WT was increased by 304±101 % (P<0.05) but that of inferior-to-anterior WT was unchanged (P<0.84), suggesting that the amelioration of the non-uniform WT between the septal and lateral regions contributed to the efficacy of CRT. The acute pacing on/off study at the post-QGS showed similar results (n=14). After 6 months with CRT, follow-up QGS revealed that the responders (n=9) exhibited higher CVWT at the pre-QGS (0.68±0.09 vs. 0.36±0.04, P<0.05) and a more marked reduction in CVWT after the first 2 weeks with CRT (−25±17 vs. + 37±11 %; P<0.05) than the non-responders (n=6). At this chronic stage, the reduction in CVWT after the first 2 weeks of CRT was linearly correlated with the % decrease in ESV (r=0.57) and EDV (r=0.57), and the increase in EF (r=0.55) (all P<0.05).
Conclusions: These results suggest that QGS is a useful method to evaluate the initial efficacy of CRT and to predict LV reverse remodeling in the chronic phase.