The Impact of Response to Cardiac Resynchronization Therapy on Ventricular Arrhythmic Events in CUBIC Registry

Background: It is well known that CRT is effective to reduce heart failure hospitalization and prolong survival. However, the impact of response to CRT on ventricular arrhythmias (VA) is not well established. Methods: We investigated 436 patients without history of VA, who could obtain pre and 6 month echo data, from CUBIC study which is a Japanese multicenter CRT registry (age 70+/-11years, NYHA class 2.9+/-0.6, female 32%, ischemic etiology29%, LVEF 28+/-10%, LVEDD 62+/-9mm, QRS duration 151+/-37ms, CRT-D 54%) and divided into two groups, 262 (60%) CRT responders (R-group) and 174 (40%) CRT non-responders (NR group). Results: After mean follow up 26+/14 months, survival rate, event free survival rate from heart failure hospitalization and event free survival rate from combined death and heart failure hospitalization were all significantly higher in R group compared to NR group (95% vs. 78% at 2-year, Log-rank p<0.0001, 83% vs. 59% at 2-year, Log-rank p<0.0001, 81% vs. 53% at 2-year, Log-rank p<0.0001, respectively). Furthermore, event free survival rate from combined VT, VF, ICD therapy for VT or VF, and sudden cardiac death was also significantly higher in R group (90% vs. 81% at 2-year, Log-rank p=0.008). Conclusion: Response to CRT seems not only to reduce heart failure events or prolong survival, but also to prevent VA.