Cardiac resynchronization therapy response in heart failure patients with different subtypes of true left bundle branch block
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Left bundle branch block (LBBB) configuration has been described as a predictor of response to cardiac resynchronization therapy (CRT). We investigated whether different subtypes of true LBBB configuration could help select patients with better response and clinical outcome.
This retrospective study included 198 consecutive LBBB patients implanted with a CRT. True LBBB was defined using the Strauss and the Predict study criteria. Echocardiographic response was evaluated by the reduction in left ventricular end-systolic volume (LVESV) and the increase in left ventricular ejection fraction (LVEF). Clinical response was defined as an improvement in one category of the NYHA functional class.
Patients with true LBBB had a greater improvement in both LVESV reduction (median = − 27.6%, interquartile range = [− 4.9, − 50.1]) and LVEF increase (median 10.8 ± 10) than those with non-true LBBB (− 19.7%, [16.7, − 48.0]) p = 0.04 and 5.1 ± 10, p = 0.03, respectively. No differences were exhibited between true LBBB Strauss group (− 26.7%, [− 11.0, − 46.9]) and true LBBB Predict group (− 26.6%, [− 15.9, − 39.4]). There were no statistically significant differences in the percentage of patients with clinical response, assessed by NYHA improvement, among all groups. In the Cox model for death, age, ischemic etiology, and ΔLVESV were independent predictors of mortality. True LBBB (Strauss + Predict) patients had a trend towards lower mortality than non-true LBBB [HR = 0.55, 95% CI = (0.22–1.15)], p = 0.08. In the Cox model for HF hospitalization, age, sex male, prior LVEF, and ΔLVESV were independent predictors. True LBBB (Strauss + Predict) patients had a significantly lower risk of developing HF hospitalization than those with non-true LBBB [0.45 (0.21–0.90)], p = 0.029.
Patients with true LBBB, either Strauss or Predict criteria, had greater echocardiographic response and lower incidence of HF hospitalization than non-true LBBB when implanted with CRT.
KeywordsLeft bundle branch block Cardiac resynchronization therapy Heart failure
J.G.S made primary contributions to the study conception and design, analysis, interpretation of results, and writing of the manuscript. B.A.A and D.I.A contributed to data collection and interpretation of results. F.G.S. contributed to design, statistical analysis and writing of the manuscript. All authors contributed to interpretation of results; all revised the manuscript critically for important intellectual content; and all approved the final manuscript.
Compliance with ethical standards
Conflict of interest
The authors report no relationships that could be construed as a conflict of interest for this publication. No funding was received for this research.
Ethical approval in research involving human participants
The study protocol was in accordance with the ethical standards of the regional research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.
Informed consent was obtained from every patient. The study protocol was approved by the Clinical Research Ethics Committee in Galicia, Spain.
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