Background:
Among patients with heart failure (HF), cardiac resynchronization therapy (CRT) combined with a defibrillator (CRT-D) reduces HF events and mortality compared with a defibrillator (ICD) alone. Whether these benefits extend to all age-groups during long-term follow-up is unclear.
Hypothesis:
We hypothesized that CRT-D would benefit all age groups with respect to reductions in HF events and all-cause mortality.
Methods:
We assessed the effect of age on HF events and death among patients in the MADIT-CRT long-term follow up study. 1281 patients with class I or II heart failure and left-bundle branch block (LBBB) were randomized to CRT-D or ICD alone. Patients were divided into 3 age groups: <60, 60-74 or ≥75 years and evaluated over 7 years for mortality and HF events. We compared cumulative events using the log-rank test and adjustments were made using a multivariate logistic regression model with various pre-specified covariates.
Results:
Overall 761 patients received CRT-D and 520 received ICD alone. The median age was 65 years. Among the three age groups, <60, 60-74 and ≥75 there were 399, 651 and 231 patients respectively. Multivariate analysis (Table) revealed that CRT-D compared to ICD alone significantly reduced the composite outcome of HF or death across all age groups: <60 years relative risk reduction (RRR)=39%, p=0.0236; 60-74 years RRR=59%, p<0.001; ≥75 years RRR=55%, p<0.001. CRT-D also significantly reduced HF events in all age groups <60 years RRR=52%, p=0.003; 60-74 years RRR=61%, p<0.001; ≥75 years RRR=73%, p<0.001. CRT-D was associated with significant mortality reduction only in the 60-74 year age group RRR 58%, p<0.001.
Conclusion:
Among patients with asymptomatic or mild heart failure, reduced LVEF and LBBB, CRT-D results in significant reduction of HF events and in the composite of all-cause mortality and HF events during long-term follow-up. All-cause mortality was significantly reduced with CRT-D only in the 60-74 year age group.
P5478QRS axis and benefit of cardiac resynchronization therapy in heart failure patients with non-Left bundle branch block, from long term follow up
