Left-bundle branch block, an alert for cardiac resynchronization therapy Characteristics of an unselected population with LBBB in Stockholm County.

BACKGROUND: The left bundle branch block (LBBB) might be the first finding of cardiovascular diseases but also the prerequisite for cardiac resynchronization therapy (CRT) in heart failure (HF) with reduced ejection fraction (HFrEF). The prognosis for patients with LBBB and the implications of CRT in an unselected real-world setting are of great interest.

METHODS: A central ECG database and national registers have been screened to identify patients with LBBB. Predictors of HF and use of CRT were identified with Cox models. The hazard ratios (HR) of death, cardiovascular death (CVD) and HF hospitalization (HFH) were estimated according to CRT use.

RESULTS: Of 5,359 patients with LBBB and QRS>150ms, median age 76 years, 36% were female. At the time of index ECG, 41% had a previous history of HF and 27% developed HF. Among 1053 patients with a class I indication for CRT, only 60% received the CRT with a median delay of 137 days and it was associated with a lower risk of death (HR: 0.45 95% CI: 0.36-0.57), CVD (HR: 0.47 95% CI: 0.35-0.63) and HFH (HR: 0.56 CI: 0.48-0.66). The age over 75 years and the diagnosis of dementia and chronic obstructive pulmonary disease were predictors of CRT non-use while having a pacing/defibrillator device independently predicted CRT use.

CONCLUSION: In an unselected LBBB population, CRT is underused but of great value for HF patients. Therefore, it is crucial to find ways of better implementing and understanding CRT utilization and characteristics that influence the management of our patients.