Long-term outcomes of upgrading to cardiac resynchronization therapy in patients with left bundle branch block or...

Data comparing outcomes between cardiac resynchronization therapy (CRT) upgrade in patients with left bundle branch block (LBBB) or right ventricular (RV) pacing and de novo CRT in LBBB are limited.

To evaluate long-term outcomes of CRT upgrade in patients with LBBB or RV pacing compared with de novo CRT in LBBB.

We analyzed 395 consecutive patients who received CRT, classified into 3 groups: CRT upgrade for LBBB or RV pacing (Upgrade group, n = 111), de novo CRT for LBBB (LBBB group, n = 84), and CRT for non-LBBB (non-LBBB group, n = 200). The primary end point was a composite of all-cause mortality and heart failure hospitalization. The secondary end point was CRT response, defined as an improvement of ≥15% in left ventricular end-systolic volume.

During the follow-up of 778 days, the risk of primary end point was higher in the Upgrade group than the LBBB group (log-rank, P = .03), and lower than the non-LBBB group (P = .03). In the Upgrade group, Kaplan-Meier analysis revealed that patients with left atrial diameter >50 mm, determined by receiver operating characteristic analysis, had a higher risk of the primary end point (log-rank, P < .001). Left atrial diameter >50 mm was a negative predictor of CRT response and an independent predictor of primary end point (hazard ratio 2.31, 95% confidence interval 1.10-4.85, P = .03).

CRT upgrade for LBBB or RV pacing offers less prognostic benefit than de novo CRT for LBBB.