Age, prognostic impact of QRS prolongation and left bundle branch block, and utilization of cardiac resynchronization therapy: findings from 14713 patients in the Swedish Heart Failure Registry

AimsAge is not a contraindication to cardiac resynchronization therapy (CRT), but the prevalence and prognostic impact of QRS prolongation with intraventricular conduction delay (IVCD) and left bundle branch block (LBBB), as well as CRT utilization, may differ with age. We tested the hypotheses that in the elderly: (i) IVCD and LBBB are more prevalent, (ii) IVCD and LBBB are more harmful, and (iii) CRT is underutilized. Methods and resultsWe studied 14713 patients with ejection fraction 39% in the Swedish Heart Failure Registry and divided into age groups 65years, 66-80years and >80years. Among 13782 patients without CRT, IVCD was present in the three age groups in 11% vs. 15% vs. 19% and LBBB was present in 20% vs. 27% vs. 28%, respectively, (P<0.001). The multivariable hazard ratio (HR) for all-cause mortality over a median (interquartile range) follow-up of 29 (12-53) months for IVCD vs. narrow QRS was 1.31 (1.06-1.63, P=0.013) in the 65year group, 1.32 (1.17-1.47, P<0.001) in the 66-80year group, and 1.26 (1.21-1.41, p<0.001) in the >80year group. For LBBB vs. narrow QRS it was 1.29 (1.07-1.56, P=0.009), 1.17 (1.06-1.30, P=0.002), and 1.10 (0.99-1.22, P=0.091), respectively. The adjusted P for interaction between age and QRS morphology was 0.664. In the three age groups, CRT was present in 6% vs. 8% vs. 4% and absent but with indication in 23% vs. 32% vs. 37%, respectively (P<0.001). ConclusionsBoth IVCD and LBBB were more common with increasing age and were similarly strong independent predictors of mortality and in all ages. The underutilization of CRT was worse with increasing age.