Risk and predictors of dyssynchrony cardiomyopathy in left bundle branch block with preserved left ventricular
Sunita Sharma1, Harsh V Barot1, Andrew D Schwartzman1
1From the Division of Cardiovascular Medicine, Lahey Hospital and Medical Center, Burlington, Massachusetts, USA.
Insights
Seventeen percent of patients with left bundle branch block (LBBB) and preserved ejection fraction develop cardiomyopathy. Serial assessment of left ventricular function is recommended for this high-risk group.
Area of Science:
- Cardiology
- Cardiac Electrophysiology
- Cardiomyopathy Research
Background:
- Left bundle branch block (LBBB) can lead to left ventricular (LV) dyssynchrony and progressive systolic dysfunction.
- Initial evaluation of LBBB typically includes screening for structural heart disease and coronary artery disease (CAD).
- The long-term risk of cardiomyopathy in LBBB patients with preserved ejection fraction (EF) is not well-established.
Purpose of the Study:
- To determine the incidence of developing LV systolic dysfunction in LBBB patients with initially preserved LVEF.
- To identify predictors for the development of cardiomyopathy in this patient cohort.
- To establish the need for serial cardiac imaging in LBBB patients with preserved LVEF.
Main Methods:
- Retrospective review of 1000 LBBB patients' records.
- Inclusion criteria: preserved LVEF (≥45%) and absence of significant CAD or other cardiomyopathy causes.
- Follow-up imaging and clinical data were collected to assess for subsequent LV systolic dysfunction (LVEF ≤40%).
Main Results:
- 17% (37 of 216) of patients developed reduced LVEF (≤40%) over a mean follow-up of 55 months.
- Baseline LVEF ≤60% and LV end-systolic diameter ≥2.9 cm were associated with increased risk.
- A preserved LVEF >60% and LV end-systolic diameter <2.9 cm had a 98% negative predictive value.
Conclusions:
- A significant proportion of LBBB patients with preserved LVEF develop dyssynchrony cardiomyopathy.
- Serial assessment of LV systolic function is warranted in this high-risk population.
- Specific baseline parameters can help identify patients needing closer monitoring.
Background:
Left bundle branch block (LBBB) and left ventricular (LV) dyssynchrony likely contribute to progressive systolic dysfunction. The evaluation of newly recognized LBBB includes screening for structural heart abnormalities and coronary artery disease (CAD). In patients whose LV ejection fraction (EF) is preserved during initial testing, the incidence of subsequent cardiomyopathy is not firmly established.
Hypothesis:
The risk of developing LV systolic dysfunction among LBBB patients with preserved LVEF is high enough to warrant serial imaging.
Methods:
We screened records of 1000 consecutive patients with LBBB from our ECG database and identified subjects with an initially preserved LVEF (≥45%) without clinically relevant CAD or other cause for cardiomyopathy. Baseline imaging, clinical data, and follow-up imaging were recorded to determine the risk of subsequent LV systolic dysfunction (LVEF ≤40%).
Results:
(Data are mean + SD) 784 subjects were excluded, the majority for CAD or depressed LVEF upon initial imaging. Of the remaining 216, 37 (17%) developed a decline in LVEF(≤40%) over a mean follow-up of 55 ± 31 months; 94% of these patients had a baseline LVEF≤60% and LV end systolic diameter (ESD) ≥ 2.9 cm indicating that these measures may be useful to define which patients warrant longitudinal follow-up. The negative predictive value of a LVEF>60% and LVESD <2.9 cm was 98%.
Conclusions:
Seventeen percent of patients with LBBB and initial preserved LVEF develop dyssynchrony cardiomyopathy. We believe the risk of developing dyssynchrony cardiomyopathy is high enough to warrant serial assessment of LV systolic function in this high-risk population.
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