Management of atrial fibrillation: focus on catheter-based ablation.

Atrial fibrillation (AF) contributes to considerable morbidity, with increasing risk of stroke, complications from anticoagulation, and exacerbation of heart failure. AF ablation has become a commonly performed procedure in many hospitals as the procedural techniques evolve rapidly with improved success. Here we discuss the interventional options of catheter-based AF ablation for rhythm control, which offers the benefit of mortality reduction associated with normal sinus rhythm but without medication complications.

Management of atrial fibrillation: focus on rate versus rhythm control.

Atrial fibrillation (AF) is the most common cardiac arrhythmia in adults and accounts for approximately one-third of all arrhythmias requiring admission to the hospital. Treatment strategies are determined by the classification of AF, whether paroxysmal or persistent, as well as numerous patient-specific cardiac and medical considerations (eg, pre-existing congestive heart failure or previous myocardial infarction). Thromboembolic risk also influences whether patients are treated with antiplatelet or anticoagulant medications. Several large clinical trials have deemed both rate and rhythm control acceptable treatment strategies for AF. Additionally, nonpharmacologic approaches such as surgical and electroablative options also exist. The clinician must exercise sound clinical judgment when deciding which treatment approach is best suited for a particular patient.

High amplitude T-wave alternans precedes spontaneous ventricular tachycardia or fibrillation in ICD electrograms.

BACKGROUND: T-wave alternans (TWA) increases acutely prior to ventricular tachycardia (VT) or fibrillation (VF) in animal studies, suggesting that it may provide a warning for VT/VF in implantable cardioverter defibrillator (ICD) patients. Clinically, measurement of surface ECG TWA requires preprocessing the input signal to reduce noise and/or analyzing more sinus beats than are recorded in ICDs as pre-onset, stored intracardiac electrograms (EGMs) before VT/VF. Our objective was to measure TWA from the few sinus EGMs stored in ICDs before spontaneous VT/VF in humans. OBJECTIVE: The purpose of this study was to evaluate the technical feasibility of measuring TWA from pre-onset ICD EGMs and to measure EGM TWA before spontaneous VT/VF in humans. METHODS: We developed a method to measure EGM TWA as a simple average (AVE) of peak-to-peak alternans. Using simulation, we determined the effect of ICD signal processing on EGM TWA for durations comparable to those in pre-onset EGMs. We then applied this method to pre-onset ICD EGMs that preceded 101 episodes of sustained VT/VF in 10 patients. In 6 of these patients, EGM recordings in atrial pacing and sinus rhythm provided control data. RESULTS: In simulation, the AVE method discriminated input TWA differences > or = 15 microV. In patients, EGM TWA was 78 +/- 62 microV prior to VT/VF vs. 13 +/- 10 microV in control recordings (p< .0001). Eighty percent of pre-onset measurements exceeded 30 microV, while 95% of control measurements were less than 30 microV. CONCLUSIONS: A simple averaging method can measure TWA preceding VT/VF in stored ICD EGMs. Pilot data indicate that high-amplitude EGM TWA usually precedes spontaneous VT/VF and is infrequent in control recordings. They provide a rationale for developing ICD technology to measure EGM TWA continuously, both to warn patients and to initiate pacing algorithms to prevent VT/VF.