RESUMO
INTRODUCTION: Left bundle brunch block (LBBB) and right ventricular stimulation (RVS) may be associated with asynchrony and heart failure. Differences between these two entities and their response to cardiac resynchronization therapy (CRT) are not well defined. METHODS: Patients receiving CRT from 1999 to 2006 were analyzed for cardiac events and prognosis separated between primary implants for LBBB (n = 221) and upgrades from RVS (n = 107). A subgroup of 105 patients (LBBB = 69; RVS = 36) was studied in more detail (New York Heart Association [NYHA], quality of life, brain natriuretic peptide, peak VO2, left ventricular ejection fraction [LVEF], wedge pressure, Cardiac Index, QRS, left-right preejection period using pulsed wave doppler, septum-lateral wall motion delay using tissue doppler imaging) at baseline and after 1 year. RESULTS: Age (68.4 +/- 11 years vs 68.7 +/- 15 years, n. s.), NYHA class (3.1 vs 3.1, n. s.), LVEF (26.4 vs 28.1, n. s.), and clinical parameters were comparable between LBBB and RVS. The latter group consisted of more patients with chronic atrial fibrillation (14% vs 37%, P = 0.03). After 1 year, NYHA class (-0.8 +/- 0.8 vs -0.6 +/- 0.8, n. s.), LVEF (+13.7 +/- 14% vs +8.7 +/- 10%, n. s.), and clinical parameters improved similarly. After a median follow-up of 2.33 +/- 1.8 years in the LBBB versus 2.43 +/- 1.9 years in the RVS group, there was no difference in long-term prognosis or cardiac events in the total cohort (5-year event rate, 53% vs 55%, P = n. s.). CONCLUSION: Upgrade patients showed similar baseline parameters and response to CRT as to primary implants. No difference in events or long-term prognosis could be observed.
