P4532PR interval prolongation, still a marker of worse outcome in patients treated with cardiac resynchronization therapy

Abstract Background Patients without left bundle branch block (non-LBBB) generally derive little benefit from CRT. Recently, CRT has been suggested to be beneficial in patients with prolonged PR interval. However in the general HF population, the presence of prolonged PR interval is associated with worse outcome. Purpose To evaluate the association of a prolonged PR interval with clinical outcome in CRT-treated LBBB and non-LBBB patients. Methods Pre-implantation 12-lead ECGs from 1.245 consecutive CRT patients without atrial fibrillation from 3 implanting centres in the Netherlands were evaluated for the presence of LBBB QRS morphology and PR interval prolongation (≥230ms). The primary endpoint was the combination of left ventricular assist device implantation, cardiac transplantation and all-cause mortality. Results Patients with LBBB (n=620) showed a significantly shorter mean PR interval than non-LBBB patients (n=625) (187ms vs 198ms, p<0.001). Prolonged PR interval was found in 12.6% of patients with LBBB and 19.2% of non-LBBB patients (P<0.001). In non-LBBB patients with PR prolongation event rate was significantly higher (54 vs 34%, p<0.001). In LBBB patients there was a non-significant difference (28 vs 20%, p=0.1). Regression analyses (figure 1) showed similar results, with a significantly higher odds of experiencing an event in non-LBBB patients with PR prolongation (HR 2.24 [1.68, 2.99], p<0.001), and a trend to significantly higher odds in LBBB patients with PR prolongation (HR 1.61 [1.02, 2.56], p=0.04) Figure 1 Conclusion In HF patients treated with CRT, PR prolongation is negatively associated with long term clinical outcome. The association seems to be stronger in non-LBBB patients than in LBBB patients. Acknowledgement/Funding None