Bundle branch block and QRS width in ICD patients. Morphology is more important than length

QRS width is a well known prognostic factor in ICD patients, however there is less information regarding bundle branch block morphology. Umbrella is a Spanish multicenter, prospective, observational registry sponsored by Medtronic including ICD patients from 39 centers followed by CareLink System. To analyze the influence of QRS width and morphology of bundle branch block in ventricular tachycardia (VT) or fibrillation (VF) recurrences, we studied patients from 27 participating centers followed between 1/04/2007 and 01/07/2012. Results: We included 568 patients (age 63.8±14, EF 33.1±9.4, QRS width 109±27ms), 77 (13.6%) of them with left bundle branch block (LBBB), and 49 (8.6%) with right bundle branch block (RBBB), and followed them during 23.3±18 months. LBBB was associated with more episodes of VT/VF, more shocks related to VT/VF and the occurrence of more than 3 episodes of VT/VF during follow-up (Table 1). Neither ejection fraction nor RBBB had any significant association to shocks or arrhythmia incidence. Width of QRS complex was only associated with a higher number of shocks (109±29 vs 120±25, p=0.002) and more than 3 episodes of VT/VF (109±29 vs 120±27, p=0.003) during follow-up. View this table: Table 1 Conclusion: Patients with LBBB had significantly more arrhythmic events compared to patients without LBBB. In our study EF and RBBB do not have prognostic relevance. QRS width has limited value. Further studies are needed to contrast these findings.