Echocardiographic Response
A comparison of the echocardiographic changes following the CRT upgrade between the 3 groups is shown in Figure 2 . A decrease in the LVESV (ΔLVESV) and increase in the LVEF (ΔLVEF) was most often seen in group 3. Also, the rate of an echocardiographic response rate was the highest in group 3 and lowest in group 1 (group 1: 2 of 7 patients [29%] vs. group 2: 5 of 10 patients [50%] vs. group 3: 21 of 27 patients [78%], p = 0.029).
Figure 3 shows the echocardiographic change between that before and six months after the upgrade to CRT in each group. There was a significant reduction in the ESV in group 3 (from 126 ± 34 mL to 91 ± 39 mL, p < 0.0001) but not in groups 1 and 2. There was a significant improvement in the EF in groups 2 and 3 (from 26 ± 7% to 34 ± 8%, p = 0.002 and from 26 ± 7% to 39 ± 9%, p < 0.0001, respectively) but not in groups 1.