"Dual-Chamber versus Ventricular Pacing in Sinus-Node Dysfunction"The New England Journal of Medicine. [Year]. [Volume](Issue):[Pages].PubMed•Full text•PDFContents1Clinical Question2Bottom Line3Major Points4Guidelines5Design6Population6.1Inclusion Criteria6.2Exclusion Criteria6.3Baseline Characteristics7Interventions8Outcomes8.1Primary Outcome8.2Secondary Outcomes9Funding10Further ReadingClinical QuestionIn patients with sinus-node dysfunction, is dual-chamber pacing superior to ventricular pacing in improving stroke-free survival?Bottom LineIn patients with sinus-node dysfunction, dual-chamber pacing did not significantly improve stroke-free survival compared to ventricular pacing. However, dual-chamber pacing was associated with reduced incidence of atrial fibrillation, fewer heart failure symptoms, and a slight improvement in quality of life.Major PointsSinus-node dysfunction often necessitates pacemaker implantation to treat bradycardia. While dual-chamber pacing preserves atrioventricular synchrony and is physiologically more similar to normal conduction, it is more expensive and complex than ventricular pacing. Earlier small trials and non-randomized studies suggested potential benefits, including reduced mortality with dual-chamber pacing, but results were inconclusive.GuidelinesExisting guidelines for the selection of pacing systems were primarily based on small clinical studies and retrospective analyses.DesignMulticenter, double-blind, randomized controlled trialN=2,010 patients with sinus-node dysfunctionDual-chamber pacing (n=1,014)Ventricular pacing (n=996)Median follow-up: 33.1 monthsPrimary outcome: Death from any cause or nonfatal strokeSecondary outcomes: A composite of death, stroke, or hospitalization for heart failure; atrial fibrillation; heart failure score; pacemaker syndrome; quality of lifeAnalysis: Intention-to-treatPopulationInclusion CriteriaPatients aged ≥21 yearsScheduled for initial dual-chamber, rate-modulated pacing system implantationIn sinus rhythm at randomizationExclusion CriteriaSerious concurrent illnessesImpaired cognitive function (Mini–Mental State Examination score <17)Baseline CharacteristicsMedian age: 74 years48% femaleHistory of hypertension: 62%Diabetes: 22%History of myocardial infarction: 26%History of heart failure: 20%InterventionsFollowing successful implantation of atrial and ventricular leads, patients were randomized to receive either dual-chamber or ventricular pacing before permanent implantation.OutcomesPrimary OutcomeDeath or nonfatal stroke occurred in 21.5% of dual-chamber group vs. 23.0% of ventricular-paced group (P=0.48).Secondary OutcomesAtrial fibrillation developed in 24.2% overall; significantly lower rate in dual-chamber group (HR 0.79; 95% CI, 0.66 to 0.94; P=0.008).Adjusted analyses showed marginally significant reductions in hospitalization for heart failure and combined clinical endpoint with dual-chamber pacing.Heart-failure score better in dual-chamber group (P<0.001).Small improvements in SF-36 quality-of-life scores with dual-chamber pacing.High incidence (16.5%) of crossover to dual-chamber pacing in ventricular pacing group due to pacemaker syndrome.FundingSupported by grants from the National Heart, Lung, and Blood Institute (NHLBI), Medtronic, Guidant, and St. Jude Medical.Further ReadingAuthors of the study have financial affiliations with the support and manufacturing companies of the devices used in the trial.