Performance of a ventricular automatic-capture algorithm in a wide clinical setting.

BACKGROUND: The optimal programming of a pacemaker (PM) voltage output considers both efficiency (prolonging battery cell longevity) and patient safety (adequate safety margin). Currently, automatic capture (AC) algorithms are designed to ensure safe automatic stimulation threshold determination and pacing with a safety margin. METHODS: The aims of this prospective observational study were (1) to evaluate, over a short-term follow-up, the extent of backup pacing in patients implanted with an AC-featured PM produced by Boston Scientific (Insignia) and a wide range of ventricular leads; (2) to identify patient- or lead-specific predictors of ventricular threshold increase or missed detection of the ventricular pacing threshold; and (3) to analyze day-to-day fluctuations in the ventricular pacing threshold and the relationship between their magnitude, the characteristics of patients, and the system implanted. RESULTS: Five hundred and seventy-nine patients implanted with 89 different leads were followed up for a median of 2.1 months. Five hundred and thirty-six patients (92.5%) never experienced failure of automatic threshold testing; 571 (98.6%) did not experience permanent failure requiring continuous backup pacing at high energy. On multivariate analysis, none of the patient or lead characteristics predicted the occurrence of high-energy backup pacing during the study period. Day-to-day threshold fluctuations were associated only with higher thresholds (>1 V). CONCLUSION: AC algorithm reliably measures ventricular pacing thresholds in most patients: in only 1.4% of patients the system is permanently unable to detect the ventricular threshold. Backup pacing is not dependent on lead or patient characteristics, including lead polarization, polarity, and maturation.

Efficacy of ultrasound-guided axillary/subclavian venous approaches for pacemaker and defibrillator lead implantation: a randomized study.

PURPOSE: Subclavian access is a reliable technique for lead insertion in pacemaker and defibrillator (ICD) implantation, but it is often accompanied by complications. The aim of this study was to compare the efficacy of the ultrasound-guided axillary approach to the subclavian method. METHODS: This randomized comparative study was performed on 174 patients: as a first attempt, 116 patients underwent the ultrasound-guided axillary access and 58 patients underwent the subclavian approach. A total of 364 leads were placed. Operators were trained in ultrasound-guided vein access technique. RESULTS: Axillary access was successful in 69% of patients (32/46), in the training phase and, as a first attempt, in 91.4% of patients (106/116), in the randomized phase. When axillary approach failed, we performed the following: subclavian access in 5.2% of patients (6/116), cephalic approach in 2.6% of patients (3/116), surgical method in 0.9% of patients (1/116). The subclavian technique was effective, as a first attempt, in 55 patients (94.8%). When the subclavian access failed, the ultrasound axillary approach successfully performed in all three cases. During a mean follow-up of 18 ± 6 months, the number of lead complications was similar in the subclavian group compared to the axillary group (p = 0.664). CONCLUSIONS: As first attempt, ultrasound-guided axillary method showed similarly high-success rate than subclavian approach and well performed when the first attempt in subclavian group failed. Axillary access can be considered a safe and effective alternative technique to the conventional subclavian method for device implantation.

Electrical treatment of atrial arrhythmias in heart failure patients implanted with a dual defibrillator CRT device. Results from the TRADE-HF study.

BACKGROUND: Ventricular and atrial arrhythmias commonly occur in heart failure patients and are a significant source of symptoms, morbidity and mortality. Some specific generators referred to as dual defibrillators, Dual CRT-Ds, have the ability to treat atrial and ventricular arrhythmias. TRADE-HF is a prospective two-arm randomized study aimed at assessing the benefits of complete automatic management of atrial arrhythmias in patients implanted with a dual CRT-D. METHODS: Primary objective of the TRADE-HF study was to document reduction of unplanned hospital admission for cardiac reasons or death for cardiovascular causes or progression to permanent AF, by comparing fully-automatic device driven therapy for atrial tachycardia or fibrillation (AT/AF) to an in-hospital approach for treatment of symptomatic AT/AF. Randomized Patients were followed every 6months for 3years to assess the primary objective. RESULTS: Four-hundred-twenty patients have been enrolled in the study. At the end of the study 30 subjects died for cardiovascular causes, 60 had at least one hospitalization for cardiovascular causes and 14 developed permanent AF. Eighty-seven patients experienced a composite event. Hazard Ratio for device-managed automatic therapy arm compared to traditional was 0.987 (95% CI: 0.684-1.503; p=0.951). The primary endpoint analysis resulted in no difference between the device managed and in-hospital treatment arm. CONCLUSION: The TRADE-HF study failed to demonstrate a reduction in the composite of unplanned hospitalizations for cardiovascular causes or death for cardiovascular causes or progression to permanent AF using automatic atrial therapy compared to a traditional approach including hospitalization for symptomatic episodes and/or in-hospital treatment of AT/AF.