Results
The baseline characteristics during CRT upgrades exhibited no significant differences in the echocardiographic data between the three groups. After the CRT upgrade, responses regarding the ejection fraction (EF) and end-systolic volume (ESV) were significantly lower in CS patients than non-CS patients (ΔEF: group 1, 6.7% vs. group 2, 7.7% vs. group 3, 13.6%; p=0.039, ΔESV: 3.0 mL vs. -12.7 mL vs. -37.2 mL; p = 0.008). The rate of an echocardiographic response was lowest in group 1 (29%). There were, however, no significant differences in the cumulative freedom from a composite outcome among the three groups (p = 0.19). No cardiovascular deaths occurred in group 1.