Left Bundle Branch Pacing Versus Biventricular Pacing for Cardiac Resynchronization Therapy
Condition: Chronic Heart Failure
MeSH terms: Heart Failure
Study type: Interventional

Summary: 
      The present study will recruit 40 symptomatic heart failure patients with left ventricular
      ejection fraction (LVEF) below 35% and complete left bundle branch block(QRSd≥130 ms). Each
      patient was randomized to either left bundle branch pacing(LBBP) or biventricular
      pacing(BivP) and was followed up for at least 6 months. The objective is to compare the
      effects of LBBP and BivP on cardiac resynchronization in the treatment of heart failure by
      measurable clinical parameters.
    

Detailed description: 
      The traditional biventricular pacing (BivP) is an established treatment to corrected the
      cardiac dyssynchrony in heart failure patients with left bundle branch block(LBBB). It has
      been proved that BivP can improve clinical symptoms and reduce all-cause mortality in heart
      failure. However, BivP is subject to the variable coronary sinus(CS) anatomy and LV-pacing
      lead fail to be implanted in 5%-10% of patients due to the lack of appropriate target branch,
      high threshold or phrenic nerve stimulation. Almost 30%-40% of patients with successful
      implantation show no response. What's more, BivP just corrects the mechanical dyssynchrony
      caused by LBBB not corrects the LBBB. Recent studies have demonstrated that His bundle pacing
      (HBP) can correct LBBB, achieve physiological pacing and realize the cardiac
      resynchronization. But HBP has high technical requirements, lower sense value and higher
      threshold of correcting LBBB, which may be further increased in long-term follow-up.

      The lastest research shows that pacing left ventricular septum using a transseptal approach
      can reduce left ventricular(LV) electrical dyssynchrony. Huang et al first confirmed that
      left bundle branch pacing(LBBP) can correct LBBB and improve cardiac function. LBBP has been
      reported to offer higher success rate with higher sense value and lower pacing thresholds
      compared with HBP. In chronic heart failure patients with LBBB that need cardiac
      resynchronization therapy(CRT), LBBP can achieve the similar electrical and mechanical
      resynchronization as well as HBP.

      There is to date no randomized studies between LBBP and BivP in HFrEF patients with complete
      LBBB that need CRT. The purpose of this study is to compare the therapeutic effects of LBBP
      and conventional BivP on LV function and clinical endpoints in such patients. The present
      study will randomize 40 patients in two centres to LBBP or BivP. Baseline assessments
      including echocardiography parameters[left ventricular ejection fraction(LVEF ), left
      ventricular end-systolic volume(LVESV), left ventricular end-diastolic volume(LVEDV)],
      electrocardiogram(ECG), N-terminal pro B-type natriuretic peptide(NT-proBNP) level, New York
      Heart Association(NYHA) class, 6-minute walking distance(6MWD) and quality of life score(QOL)
      will be obtained. At the same time, the LBBP and BivP success rate, intraoperative and
      postoperative complications are recorded.
    

Intervention name(s): Left bundle branch pacing; Biventricular pacing
Intervention type(s): Procedure; Procedure
Intervention description(s): Successful LBBP was defined as (1) LBBP lead is located at 1.5-2cm from His-bundle towards right ventricular apex; (2) Paced QRS morphology of right bundle branch delay(CRBBD) in lead V1; (3) Stimulus to the peak of R wave in V5 and V6 QRS wave, which represents left ventricular activation time(Stim-LVAT), is less than 100ms and constant at high and low output pacing; (4) Unipolar pacing threshold<1.5V/0.5ms; (5) Recording P potential when narrow QRS escape rhythm or CRBBB escape rhythm(not essential).; Implantation of a LV pacing lead is attempted using the standard-of-care technique first.
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Double (Care Provider, Outcomes Assessor)
Primary purpose: Treatment
Keywords: cardiac resynchronization therapy; chronic heart failure; left bundle branch pacing; biventricular pacing