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 (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).
Conclusion: In HF patients treated with CRT, PR prolongation is negatively associated with long term clinical outcome. This association seems to be stronger in non-LBBB patients than in LBBB patients.