Biventricular Pacing for Atrioventricular Block and Systolic Dysfunction

Biventricular Pacing for Atrioventricular Block and Systolic Dysfunction

Curtis AB, et al; Biventricular versus RV Pacing in HF Patients with Atrioventricular Block (BLOCK-HF) Trial Investigators

N Engl J Med. 2013;368:1585-93

Leonardo Paskah Suciadi, MD

Cardiology & Vascular Medicine, Universitas Padjadjaran-Bandung-Indonesia

BACKGROUND• Trials of CRT have included pts with advanced

systolic HF, sinus rhythm, and prolonged QRS excluded pts with AVB

• RV pacing restoring an adequate HR in pts with AVB

RV apical pacing may lead to progressive LV dysfunction

• Hypothesis: biventricular pacing is superior to RV pacing in AVB pts with mild-moderate HF in a composite outcome consisting of death from any cause, an urgent care visit for HF, or an increase of 15% or more in the LVES volume index

METHODS (1); Subjects

Inclusion:Pts with high-degree AVB indicated for pacemaker

+ systolic HF NHYA fc.I-III

Exclusion:-ACS- PCI within last 30 d- previous cardiac implantable electrical device- valvular disease indicated for surgery- indication for a CRT device (according to the guidelines)

NB: Some subjects underwent PCI implantation for the primary prevention of SCD

METHODS (2); Study Procedure• A prospective, multicenter, randomized double-blind

trial

High degree AVB indicated for pacemaker implantation

Baseline visit ;Randomization (1:1) to receive either RV pacing or biventricular pacing

The pts were followed every 3 months until a predefined trial-stopping rule was satisfied

Clinical assessment every 6 months; NYHA class, HF stage, QoL, device interrogations

Echocardiography evaluation (at baseline visit, 6, 12, 18, and 24 month);LVEF, LV end-systolic volume index

METHODS (3); Outcome Measures

• Primary outcome:– Death from any cause– Urgent care visit for HF symptoms– Increased in the LVES-volume index of 15% or more

• Secondary outcome:– Death or urgent care visit for HF– Death or hospitalization for HF– Death– Hospitalization for HF

METHODS (3); Statistical Analysis

• Adaptive Bayesian study design randomization

• An intention-to-treat analysis served as the primary analysis for all outcomes

• Hierarchical Bayesian proportional-hazards model was used for analysis of the primary and secondary outcomes

• Kaplan-Meier curves were generated for each outcome in each of the study groups

RESULTS (1)

• 58 centers in US + 2 centers in Canada• December 2003 – November 2011• A total of 918 pts was enrolled; 691 of them

underwent randomization• Implantation of a pacemaker or ICD was

attempted in 809 pts successful in 758 pts (93.7%)– Unsuccessful: inability to cannulate the coronary-

sinus ostium (16 pts), dislodgement (11), unacceptably high pacing threshold (11)

• Length of follow-up: mean of 37 months

RESULTS (2); Enrollment, randomization, follow-up

918 pts were assessed for eligibility

691 underwent randomization

349 biventricular pacing 342 RV pacing

42 withdrew or were lost to FU75 died13 crossed over to RV pacing

3 met primary end point before crossover

349 were included in the analysis83 had data censored for primary end point owing to missing LVES-VI data

50 withdrew or were lost to FU90 died84 crossed over to bivent pacing

50 met primary end point before crossover

342 were included in the analysis

71 had data censored for primary end point owing to missing LVES-VI data

- Implantation of a pacemaker or ICD was attempted in 809 pts and was successful in 758 (93.7%).

- 67 pts underwent implantation but didn’t undergo randomization

Freedom from a primary-outcome event

HR 0.74; 95% CI (0.60-0.90)

Freedom from the clinical components of the primary outcome, included death from any cause or an urgent care visit for HF.

HR 0.73; 95% CI (0.57-0.92)

DISCUSSION (1)

Pts with AVB + LV dysfunction + mild-moderate HF,

WITHOUT indication of CRT based on current guidelines

Biventricular pacing is superior than RV apical pacing; Lower incidence of HF symptoms deterioration,

progression of HF, and death

HR in the pacemaker and ICD groups showeda similar clinical effect, despite a marked

difference in the mean EF in these two groups

Biventricular pacing is unlikely to be tightly linked to the ejection fraction.

DISCUSSION (2)

• This study has shown another evidence that biventricular pacing in pts with AVB preserves LV systolic function

• Previous studies of RV pacing adverse outcomes related to HF;– The Mode Selection Trial in Sinus-Node Dysfunction

(MOST): >40% increased risk of HF hospitalization.1

– The Dual Chamber and VVI Implantable Defibrillator (DAVID): higher risk of a combined outcome of death of any cause or HF hospitalization.2

• Potential alternative sites of pacing: RVOT and His Bundle evidence ??

1. Lamas GA, Lee KL, Sweeney MO, et. N Engl J Med 2002;346:1854-62.2. Wilkoff BL, Cook JR, Epstein AE, et al.JAMA 2002;288:3115-23.

Study Limitations

High number of crossover pts (97 pts) Intention to treat design High number of data censoring and exclusion

because of missing of echocardiograms (154 pts)

Leonardo Paskah Suciadi, MD