Seth J. Worley

Irrigated Radiofrequency Catheter Ablation Guided by Electroanatomic Mapping for Recurrent Ventricular Tachycardia After Myocardial Infarction The Multicenter Thermocool Ventricular Tachycardia Ablation Trial

Background— Recurrent ventricular tachycardia (VT) is an important cause of mortality and morbidity late after myocardial infarction. With frequent use of implantable cardioverter-defibrillators, these VTs are often poorly defined and not tolerated for mapping, factors previously viewed as relative contraindications to ablation. This observational multicenter study assessed the outcome of VT ablation with a saline-irrigated catheter combined with an electroanatomic mapping system. Methods and Results— Two hundred thirty-one patients (median LV ejection fraction, 0.25; heart failure in 62%) with recurrent episodes of monomorphic VT (median, 11 in the preceding 6 months) caused by prior myocardial infarction were enrolled. All inducible monomorphic VTs with a rate approximating or slower than any spontaneous VTs were targeted for ablation guided by electroanatomic mapping during sinus rhythm and/or VT. Patients were not excluded for multiple VTs (median, 3 per patient) or unmappable VT (present in 69% of patients). Ablation abolished all inducible VTs in 49% of patients. The primary end point of freedom from recurrent incessant VT or intermittent VT after 6 months of follow-up was achieved for 123 patients (53%). In 142 patients with implantable cardioverter-defibrillators before and after ablation for intermittent VT who survived 6 months, VT episodes were reduced from a median of 11.5 to 0 (P<0.0001). The 1-year mortality rate was 18%, with 72.5% of deaths attributed to ventricular arrhythmias or heart failure. The procedure mortality rate was 3%, with no strokes. Conclusions— Catheter ablation is a reasonable option to reduce episodes of recurrent VT in patients with prior myocardial infarction, even when multiple and/or unmappable VTs are present. This population remains at high risk for death, warranting surveillance and further study.

USE OF A REAL-TIME THREE-DIMENSIONAL MAGNETIC NAVIGATION SYSTEM FOR RADIOFREQUENCY ABLATION OF ACCESSORY PATHWAYS

Using conventional technology, accessory pathway abiation often requires prolonged exposure of the team and patient to ionizing radiation. Further, although the primary success rate (approximately 90%) and the rate of recurrence (approximately 10%) are acceptable, there is room for improvement. Finally, inadvertent ablation of the compact node and A V/His‐Purkinje system still occurs particularly with septal accessory pathways. The Biosense CAHTO Nonfluoroscopic Mapping and Navigation System (CARTO® System) when used to locate the accessory pathway and guide delivery of radio frequency energy lo the accessory pathway, has the potential to reduce radiation exposure, improve primary ablation success, and reduce the rate of recurrence and improve safety. This article describes our experience with the CARTO Biosense System relating to setting up the CARTO System specifically for WPW mapping/ablation, and features of the CARTO System, which are particularly advantageous for mapping and ablation of accessory pathways.

Postoperative Performance of the Quartet® Left Ventricular Heart Lead

Promote® Q CRT‐D and Quartet® LV Lead Study. Introduction: The Quartet® left ventricular (LV) lead is the first with 4 pacing electrodes (tip and 3 rings) that enables pacing from 10 different pacing vectors. Postoperative performance of this lead was evaluated in a prospective, nonrandomized, multicenter IDE study.

Safety and Efficacy of Multipoint Pacing in Cardiac Resynchronization Therapy: The MultiPoint Pacing Trial

OBJECTIVESnThe MultiPoint Pacing (MPP) trial assessed the safety and efficacy of pacing 2 left ventricular sites with a quadripolar lead in patients with heart failure indicated for a CRT-D device.nnnBACKGROUNDnCardiac resynchronization therapy nonresponse is a complex problem where stimulation of multiple left ventricular sites may be a solution.nnnMETHODSnEnrolled patients were indicated for a CRT-D system. Bi-ventricular (Bi-V) pacing was activated at implant. Three months later, clinical response was assessed and the patient was randomized (1:1) to receive Bi-V pacing or MPP. Patients were followed for 6 months post-randomization and clinical response was again assessed.nnnRESULTSnThe CRT-D system was successfully implanted in 455 of 469 attempted implants (97%). A total of 381 patients were randomized to Bi-V or MPP at 3 months. The primary safety endpoint was met with freedom from system-related complications of 93.2%. The primary efficacy endpoint of the noninferiority comparison of nonresponder ratesxa0between the 2 arms was met. Patients randomized to MPP arm and programmed to pace from anatomically distant poles (MPP-AS) responded to therapy at significantly higher rates than MultiPoint pacing-other programmed settings (MPP-Other). Within this group, 87% were responders at 9 months, 100% designated as nonresponders at 3xa0months converted to responders at 9 months, and 54% experienced an incremental response compared to MPP-Other. Also within MPP-AS, 92% of patients with de novo CRT-D implant were classified as responders compared with patients with MPP-Other.nnnCONCLUSIONSnMPP is safe and effective for treating heart failure. The study met the pre-specified hypothesis thatxa0response to MPP is noninferior to Bi-V pacing with a quadripolar left ventricular lead. (MultiPoint Pacing IDE Study [MPPxa0IDE]; NCT01786993).

Bachmann's Bundle Versus Right Atrial Appendage Capture

BAILIN, S.J., et al .: Bachmanns Bundle Versus Right Atrial Appendage Capture. The tissue in the high intraatrial septum in the region of Bachmanns Bundle (BB) exhibits electrophysiological properties that differ from the right atrial appendage (RAA). As BB pacing emerges as an alternative to RAA pacing, the feasibility of using automatic capture recognition technology in this location should be examined. At implant, active‐fixation leads were consecutively placed in the RAA, then the BB in 18 patients (55.5% men, mean age 77.1 ± 9.1 ). There was no significant difference between BB and RAA in the average capture threshold (1.12 vs 1.77 V, P = 0.09), sensing threshold (3.85 vs 3.69 mV, P = 0.84), impedance (508 vs 529 Ohms, P = 0.64), evoked response (1.78 vs 1.67 mV, P = 0.83), and polarization (0.41 vs 0.46 mV, P = 0.84) between. The difference in tissue characteristics was not associated with a different evoked response measured by the ventricular capture recognition algorithm. Based on the analogous evoked response and polarization values, capture recognition technology designed for the atrium will most likely be applicable at both pacing sites. (PACE 2003; 26[Pt. II]:264–267)

Rationale and design of a randomized trial to assess the safety and efficacy of MultiPoint Pacing (MPP) in cardiac resynchronization therapy: The MPP Trial

Although the majority of Class III congestive heart failure (HF) patients treated with cardiac resynchronization therapy (CRT) show a clinical benefit, up to 40% of patients do not respond to CRT. This paper reports the design of the MultiPoint Pacing (MPP) trial, a prospective, randomized, double‐blind, controlled study to evaluate the safety and efficacy of CRT using MPP compared to standard biventricular (Bi‐V) pacing.