October 9, 2023Open Access
View Full PaperLBBB and heart failure—Relationships among QRS amplitude, duration, height, LV mass, and sex
Key Result
Female sex was associated with a greater CRT response rate compared to men (84% vs. 58%, p<0.001) in patients with true LBBB, and QRS duration correlated strongly with LV mass.
Study Design
Type
Cohort (n=220)
Structured PICO
How do QRS amplitude and duration correlate with height, LV mass, and sex in heart failure patients with true LBBB undergoing CRT?
P
Population
220 patients with 'true' LBBB and heart failure (mean LVEF 21%, mostly NYHA II-III).
E
Exposure
Cardiac resynchronization therapy (CRT)
O
Outcome
Correlation of QRS duration and amplitude with patient height and LV mass, and CRT response rate (LVEF increased ≥5%)surrogate
In heart failure patients with true LBBB, QRS duration correlates with LV mass rather than height, and women have higher CRT response rates despite shorter QRS durations, suggesting LV mass is a significant non-electrical modifier of QRS duration.
Main Result
Absolute Event Rate: 84% vs 58%
p-value: p=<.001
Abstract
BACKGROUND: Height, left ventricular (LV) size, and sex were proposed as additional criteria for patient selection for cardiac resynchronization therapy (CRT) but their connections with the QRS complex in left bundle branch block (LBBB) are little investigated. We evaluated these. METHODS: Among patients with "true" LBBB, QRS duration (QRSd) and amplitude, and LV hypertrophy indices, were correlated with patient's height and LV mass, and compared between sexes. RESULTS: In this study cohort (n = 220; 60 ± 12 years; left ventricular ejection fraction LVEF 21 ± 7%; mostly New York Heart Association II-III, QRSd 165 ± 19 ms; 57% female; 70% responders LVEF increased ≥5%), LV mass was increased in all patients. QRS amplitude did not correlate with LV mass or height in any individual lead or with Sokolow-Lyon or Cornell-Lyon indices. QRSd did not correlate with height. In contrast, QRSd correlated strongly with LV mass (r = .51). CRT response rate was greater in women versus men (84% vs. 58%, p < .001) despite shorter QRSd 7% shorter (p < .0001). QRSd normalized for height resulted in a 2.7% and for LV mass 24% greater index in women. CONCLUSION: True LBBB criteria do not exclude HF patients with increased LV mass. QRS amplitudes do not correlate with height or LV mass. Height does not affect QRSd. However, QRSd correlates with LV size. QRSd normalized for LV mass results in 24% greater value in women in the direction of sex-specific responses. LV mass may be a significant nonelectrical modifier of QRSd for CRT.