Title: Loss of Pace Capture on the Ablation Line: A New Marker for Complete Radiofrequency Lesions to Achieve Pulmonary Vein Isolation
Topic: Arrhythmias
Date Posted: 4/2/2010
Author(s): Steven D, Reddy VY, Inada K, et al.
Citation: Heart Rhythm 2010;7:323-330.
Clinical Trial: No
Study Question: How useful is pacing on antral ablation lines for identifying target sites for pulmonary vein (PV) isolation?
Methods: Antral radiofrequency (RF) catheter ablation was performed in 30 patients (mean age 57 years) with paroxysmal atrial fibrillation. Ablation sites were tagged on an electroanatomical mapping system. A ring catheter was positioned in the PVs, but the operators were blinded to the electrogram recordings during ablation. Pacing was performed at 10 mA (2 ms pulse width) along the antral ablation line, and additional ablation was performed at sites of atrial capture until loss of capture was achieved along the entire ablation line. Bidirectional PV conduction block then was assessed with the ring catheter and by pacing within the PVs.
Results: Loss of capture along the entire antral ablation line was achieved for all pairs of ipsilateral PVs. Loss of pacing capture was associated with complete PV isolation by conventional criteria for 95% of ipsilateral PV pairs. Retrospective analysis of ring catheter recordings demonstrated that loss of capture along the antral ablation line required a mean of 10 additional RF applications beyond the point at which PV entrance block was achieved based on ring catheter electrograms.
Conclusions: Loss of pacing capture along antral ablation lines is a reliable indicator of PV isolation.
Perspective: The new technique described in this study has two advantages over existing endpoints for antral ablation to isolate the PVs: 1) only one catheter is required in the left atrium, and 2) loss of capture may be a more reliable indicator of complete conduction block than loss of PV potentials on a ring catheter. Fred Morady, M.D., F.A.C.C.
Title: Carotid Sinus Syndrome, Should We Pace? A Multicentre, Randomised Control Trial (Safepace 2)
Topic: Arrhythmias
Date Posted: 4/2/2010
Author(s): Ryan DJ, Nick S, Colette SM, Roseanne K.
Citation: Heart 2010;96:347-351.
Clinical Trial: yes
Study Question: Does pacing reduce falls in elderly patients with cardioinhibitory carotid sinus hypersensitivity (CICSH)?
Methods: The subjects of this study were 141 patients over the age of 65 years (mean age 78 years) who had a mean of approximately five falls in the prior year and ≥3 seconds of asystole during carotid sinus massage. They were randomly assigned to receive an implantable loop recorder (ILR, n = 71) or a dual-chamber pacemaker (n = 70). The 1° endpoint was the number of falls during 24 months of follow-up.
Results: The risk of falling during follow-up decreased by approximately 75% in both study groups. There was no significant difference in the number of falls during follow-up between the ILR and pacemaker groups. No episodes of asystole were recorded by the ILRs.
Conclusions: Pacing is of questionable value in elderly patients with falls and CICSH.
Perspective: The results dramatically demonstrate the nonspecific nature of a positive response to carotid sinus massage and also the placebo value of device implantation, even when the device is purely diagnostic. A prior single-center study (Safepace 1) reported that pacing did reduce the number of falling episodes in elderly patients with CICSH, but based on the results of this multicenter study, an ILR would seem more appropriate. Pacemaker implantation should be reserved for patients demonstrated to have symptomatic bradycardia or asystole. Fred Morady, M.D., F.A.C.C.
|