Atrial pacing minimization in sinus node dysfunction and risk of incident atrial fibrillation: a randomized trial.

BACKGROUND AND AIMS: High percentages of atrial pacing have been associated with an increased risk of atrial fibrillation. This study is aimed at evaluating whether atrial pacing minimization in patients with sinus node dysfunction reduces the incidence of atrial fibrillation. METHODS: In a nationwide, randomized controlled trial, 540 patients with sinus node dysfunction and an indication for first pacemaker implantation were assigned to pacing programmed to a base rate of 60 bpm and rate-adaptive pacing (DDDR-60) or pacing programmed to a base rate of 40 bpm without rate-adaptive pacing (DDD-40). Patients were followed on remote monitoring for 2 years. The primary endpoint was time to first episode of atrial fibrillation longer than 6 min. Secondary endpoints included longer episodes of atrial fibrillation, and the safety endpoint comprised a composite of syncope or presyncope. RESULTS: The median percentage of atrial pacing was 1% in patients assigned to DDD-40 and 49% in patients assigned to DDDR-60. The primary endpoint occurred in 124 patients (46%) in each treatment group (hazard ratio [HR] 0.97, 95% confidence interval [CI] 0.76-1.25, P = .83). There were no between-group differences in atrial fibrillation exceeding 6 or 24 h, persistent atrial fibrillation, or cardioversions for atrial fibrillation. The incidence of syncope or presyncope was higher in patients assigned to DDD-40 (HR 1.71, 95% CI 1.13-2.59, P = .01). CONCLUSIONS: Atrial pacing minimization in patients with sinus node dysfunction does not reduce the incidence of atrial fibrillation. Programming a base rate of 40 bpm without rate-adaptive pacing is associated with an increased risk of syncope or presyncope.

Single and dual coil shock efficacy and predictors of shock failure in patients with modern implantable cardioverter defibrillators-a single-center paired randomized study.

PURPOSE: Implantable cardioverter defibrillators (ICDs) can treat life-threatening tachyarrhythmia with high-voltage shocks. The aims were to compare the efficacy of single and dual coil shock vectors in modern ICDs and to identify predictors of shock failure. METHODS: This is a single-center paired randomized study including 216 patients with mixed indications and ICDs from four manufacturers. All patients underwent two implant defibrillation tests using single and dual coil vectors with the test order randomized. Tested shock energy differed slightly between manufacturers because of differences in device programmability: first shock approximately 15 J below maximal output-if failed, second shock approximately 10 J below maximal output-if failed, third shock at maximal output. RESULTS: First shock success rate was 399/432 (92.4%). Comparing single and dual coil vectors, no differences were seen in first shock efficacy (91.7% vs. 93.1%, P = 0.629) or lowest tested succesfully stored energy (27.2 J vs. 27.1 J, P = 0.620). All successive internal shocks failed in 4/432 (0.9%) of inductions requiring external rescue shocks to restore circulation. Multivariate predictors of first shock failure were QRS duration (relative risk 0.81 per 10 ms, P = 0.001), amiodarone treatment (relative risk 3.30, P = 0.003), and body height (relative risk 1.70 per 10 cm, P = 0.019). CONCLUSIONS: Implant defibrillation testing of modern intravenous ICD systems demonstrates high shock efficacy with no difference between single and dual coil vectors.

Implanted cardiac devices are reliably detected by commercially available metal detectors.

OBJECTIVE: Explosions of Cardiovascular Implantable Electronic Devices (CIEDs) (pacemakers, defibrillators, and loop recorders) are a well-recognized problem during cremation, due to lithium-iodine batteries. In addition, burial of the deceased with a CIED can present a potential risk for environmental contamination. Therefore, detection of CIEDs in the deceased would be of value. This study evaluated a commercially available metal detector for detecting CIEDs. DESIGN: Observational study including pacemaker patients (n = 70) and a control group without pacemaker (n = 95). The investigational device was a hand-held metal detector for detecting metal or electricity wiring. RESULTS: The metal detector detected the pacemaker in all pacemaker patients and thus exhibited a sensitivity of 100%. The specificity of the metal detector was 86%, and the negative predictive value was 100%. Thirteen individuals without pacemakers were falsely identified as having an implanted device due to implanted prosthetic material or elements of clothing. CONCLUSION: A simple hand-held metal detector may detect CIEDs with a high sensitivity. It may be of value in detecting CIEDs in deceased persons before burial or cremation. Any signal detected by the metal detector should prompt further investigation of the body and patient files.