Among patients with AF undergoing catheter ablation, atrial tissue fibrosis estimated by delayed enhancement MRI was independently associated with likelihood of recurrent arrhythmia. The clinical implications of this association warrant further investigation.

TRIAL FIBRILLATION (AF) REPresents an important public health problem. Patients with AF have an increased longterm risk of stroke, heart failure, and all-cause mortality. [1][2][3][4] Furthermore, patients with AF describe a considerably impaired quality of life (QOL) that is independent of the severity of the disease. 5,6 Restoration and maintenance of normal sinus rhythm following treat-ment directly correlates with improved QOL in these patients. [5][6][7][8] Although antiarrhythmic drugs are generally used as first-line therapy to treat patients with AF, effectiveness remains inconsistent. The likelihood of AF recurrence within 6 to 12 months approaches 50% with most drugs. [9][10][11] Antiarrhythmic drugs are also associ-ated with cumulative adverse effects over time. 1 Catheter ablation has accordingly become an alternative therapy for AF. 12 Several recent studies have See also Patient Page.

Background-It is unknown if brief episodes of device-detected atrial fibrillation (AF) increase thromboembolic event (TE) risk. Methods and Results-TRENDS was a prospective, observational study enrolling patients with Ն1 stroke risk factor (heart failure, hypertension, age Ն65 years, diabetes, or prior TE) receiving pacemakers or defibrillators that monitor atrial tachycardia (AT)/AF burden (defined as the longest total AT/AF duration on any given day during the prior 30-day period). This time-varying exposure was updated daily during follow-up and related to TE risk. Annualized TE rates were determined according to AT/AF burden subsets: zero, low (Ͻ5.

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 (PϽ0.0001). 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. (Circulation. 2008;118:2773-2782.)