Paroxysmal atrial fibrillation prevention by pacing in patients with pacemaker indication.

AIMS: The prevent-atrial fibrillation (AF) registry analyses the clinical relevance and usefulness of the four preventive pacing algorithms, available in a family of cardiac stimulators, to prevent atrial fibrillation. METHODS AND RESULTS: This study is a prospective, non-randomized, multicentre registry. Patients are eligible for the registry if they have sick sinus syndrome (SSS) with or without pre-existing atrial fibrillation. The preventive pacing algorithms were programmed for each patient on an individual basis using the diagnostic features of the devices. In the period from April 2000 to April 2001 a total of 68 patients (33 male, 35 female) has been included in the registry in 14 hospitals in Spain. Mean age was 72+/-12 years and the pacemaker indication was SSS in 15 patients (22%) and SSS with paroxysmal AF in 53 patients (78%). The median AF burden for the total group (n=32) was significantly reduced from 3.9 to 1.3% (67%, P=0.034, Wilcoxon signed rank test). The decrease in AF burden was accompanied by a non-significant decrease in the median number of episodes per day from 1.47 to 0.64 (a decrease of 56%). The average atrial pacing % was increased from 72 to 78%. CONCLUSIONS: The prevent-AF registry demonstrated the usefulness of four preventive pacing algorithms in daily clinical practice. During the registry a significant reduction in AF burden and all other endpoints was observed. Dedicated diagnostics were key to adapting the optimal pacing therapy during follow-up.

Comparison of defibrillation thresholds using monodirectional electrical vector versus bidirectional electrical vector.

BACKGROUND: Currently, two main lead configurations are used for implantable cardioverter-defibrillators (ICD). One generates a monodirectional electrical vector by using the can surface as an active part (hot can) together with a right ventricular defibrillation coil. The other one (TRIAD) produces a bidirectional electrical vector by adding a proximal defibrillation electrode on the same lead. The purpose of this prospective study was to determine whether there is a difference between these configurations in terms of the acute defibrillation threshold (DFT). The secondary objective was to evaluate the possible sequential effect of successive arrhythmia induction and defibrillation shocks on the final DFT value. METHODS: In 44 patients (37 males, 7 females, mean age 59.18 +/- 12.05 years; mean ejection fraction 35.21 +/- 11.69%), a Hot Can Ventak family ICD (Guidant, St. Paul, MN, USA) was implanted in a left pectoral pocket. During the implant procedure, step-down to failure DFT testing was performed twice in each patient using the two different above-mentioned configurations: the bidirectional and the monodirectional. The first configuration to be tested was determined by a 1:1 randomization by center. RESULTS: The step-down DFT protocol was followed in 35 patients. The average DFT was 8.6 +/- 4.0 J for TRIAD and 10.4 +/- 4.3 J for the monodirectional (p = 0.009) lead configuration; this represents a 16.3% decrease in the DFT using a bidirectional configuration. Furthermore, no relationship between the final DFT and the number of ventricular fibrillation inductions and shocks received was observed, confirming the secondary objective. CONCLUSIONS: Compared to the monodirectional electrical vector, the bidirectional electrical vector is clearly more beneficial for the patient.