No abstract

, p<0.001; ESV: 401 ± 154 mL vs. 220 ± 85 mL, p<0.001, G2 and G1, respectively). Myocardial 99m Tc-MIBI uptake was lower in G2 compared with G1 in the anterior wall (60 ± 10% vs. 67 ± 7%, p=0.049, at rest) and inferior wall (48 ± 10% vs. 59 ± 11%, at rest, and 47 ± 10% vs. 58 ± 9%, p=0.003, after adenosine stress). Summed stress score was significantly higher in G2 compared to G1 (14 ± 9 vs. 9 ± 4, G2 and G1, respectively, p=0.039). By multivariate analysis, EDV was the only independent predictor of LVEF increase posttherapy, p=0.01. By ROC curve, optimal EDV cutoff point was 315mL with 89% of sensitivity and 94% of specificity. Conclusions: CRT increased myocardial 99m Tc-MIBI uptake, improved HF functional class, and reduced QRS width independently of LV performance improvement. Post-CRT, LVEF increase occurred in hearts less dilated showing higher regional myocardial 99m Tc-MIBI uptake, mainly in the inferior wall. Descriptors: 1. Artificial pacemaker; 2. Heart failure; 3. Emission computed tomography; 4. Bundle-branch block; 5. Technetium 99mTc Sestamibi