Lateral Wall Dysfunction and Progressive Heart Failure in LBBB
Quick Takes
- LV lateral wall function is preserved in patients with LBBB and normal or moderately reduced LVEF, but reduced in patients with severely reduced LVEF.
- Progressive septal dysfunction eventually leads to LV lateral wall decompensation and reduced global LV function.
- It may potentially be beneficial to implant a CRT at a relatively early stage of LBBB-induced heart failure where LV lateral wall systolic function is preserved or compensatory increased, to achieve optimal recovery of LV function, but needs to be prospectively validated.
Study Questions:
What is the impact of lateral wall dysfunction on potential for recovery of left ventricular (LV) function with cardiac resynchronization therapy (CRT)?
Methods:
The investigators measured strain using speckle-tracking echocardiography and regional work using pressure-strain analysis in 76 nonischemic patients with left bundle branch block (LBBB) and 11 controls. Patients with LBBB were stratified according to LV ejection fraction (LVEF) ≥50% (EFpreserved), 36-49% (EFmid), and ≤35% (EFlow). Sixty-four patients underwent CRT and were re-examined after 6 months. Uni- and multivariate linear regression were used to identify predictors of LV systolic function and remodeling.
Results:
Septal work was successively reduced from controls, through EFpreserved, EFmid, and EFlow (all p < 0.005), and showed a strong correlation to LVEF (r = 0.84; p < 0.005). In contrast, LV lateral wall work was numerically increased in EFpreserved and EFmid versus controls, and did not significantly correlate with LVEF in these groups. In EFlow, however, LV lateral wall work was substantially reduced (p < 0.005). There was a moderate overall correlation between LV lateral wall work and LVEF (r = 0.58; p < 0.005). In CRT recipients, LVEF was normalized (≥50%) in 54% of patients with preserved LV lateral wall work, but only in 13% of patients with reduced LV lateral wall work (p < 0.005).
Conclusions:
The authors concluded that the advent of LV lateral wall dysfunction may be an optimal time-point for CRT.
Perspective:
This study reports that LV lateral wall function while preserved in patients with LBBB and normal or moderately reduced LVEF, is impaired in patients with severely reduced LVEF. These findings, together with stress and work analysis, indicate that progressive septal dysfunction eventually leads to LV lateral wall decompensation and reduced global LV function. Overall, these data suggest that it may be beneficial to implant a CRT at a relatively early stage of LBBB-induced heart failure where LV lateral wall systolic function is preserved or compensatory increased, to achieve optimal recovery of LV function. Additionally, prospective studies are indicated to determine if assessment of LV lateral wall function can improve selection of CRT candidates, including patients who are currently not included in the guidelines for CRT.
Clinical Topics: Arrhythmias and Clinical EP, Heart Failure and Cardiomyopathies, Noninvasive Imaging, Prevention, Implantable Devices, EP Basic Science, SCD/Ventricular Arrhythmias, Atrial Fibrillation/Supraventricular Arrhythmias, Acute Heart Failure, Echocardiography/Ultrasound
Keywords: Arrhythmias, Cardiac, Bundle-Branch Block, Cardiac Resynchronization Therapy, Diagnostic Imaging, Echocardiography, Heart Failure, Primary Prevention, Secondary Prevention, Stroke Volume, Systole, Ventricular Dysfunction, Left, Ventricular Function, Left
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