"Biventricular Pacing in Patients with Atrioventricular Block and Heart Failure".The New England Journal of Medicine. ClinicalTrials.gov number, NCT00267098.

Clinical Question

In patients with atrioventricular block and left ventricular systolic dysfunction with NYHA class I, II, or III heart failure, is biventricular pacing superior to conventional right ventricular pacing in reducing mortality, morbidity, and adverse left ventricular remodeling?

Bottom Line

For patients with atrioventricular block, mild-to-moderate heart failure, and abnormal left ventricular systolic function, biventricular pacing was found to be superior to right ventricular apical pacing in preventing death, heart failure visits requiring intravenous therapy, or significant increases in left ventricular end-systolic volume index_gpt.

Major Points

Prior studies, such as MOST and DAVID, have highlighted potential adverse outcomes associated with right ventricular pacing, including hospitalization for heart failure. This has led to the hypothesis that biventricular pacing, as used in CRT, may be a better alternative. BLOCK HF sought to compare these two pacing strategies in patients with established needs for ventricular pacing and accompanying left ventricular dysfunction.

Guidelines

Current guidelines do not explicitly recommend biventricular pacing over standard right ventricular pacing for this specific patient population; however, this trial provides evidence that may influence future recommendations.

Design

Multicenter, randomized, double-blind trial.

Population

918 patients enrolled with a successful device implantation attempted in 809 patients and successful in 758 (93.7%). Randomization occurred for 691 patients.
Inclusion Criteria:
- Atrioventricular block requiring pacing
- NYHA class I, II, or III heart failure
- Left ventricular ejection fraction ≤50%
Exclusion Criteria:
- Previous cardiac implantable electrical device
- Unstable angina, acute myocardial infarction, or recent coronary intervention
- Valvular disease requiring surgery
- Indication for CRT based on guidelines

Interventions

Patients received cardiac-resynchronization pacemakers or ICDs and were randomized to either standard right ventricular pacing or biventricular pacing.

Outcomes

Primary Outcome:
- Time to death from any cause, urgent care visit for heart failure requiring intravenous therapy, or a ≥15% increase in left ventricular end-systolic volume index_gpt.

Secondary Outcomes:
- Combined outcome of death from any cause or urgent care visit for heart failure.
- Combined outcome of death from any cause or hospitalization for heart failure.
- Separate outcomes of death from any cause and hospitalization for heart failure.

Criticisms

- A large number of patients switched from right ventricular pacing to biventricular pacing, which could have skewed the results, potentially in favor of right ventricular pacing.
- A fair number of missing echocardiograms resulted in the censoring and exclusion of some patient data from the analysis of the primary outcome.

Funding

Supported by Medtronic.

Further Reading

- Additional details provided in the Supplementary Appendix available at NEJM.org.