Defibrillation testing at the time of ICD insertion: an analysis from the Ontario ICD Registry.

BACKGROUND: increasingly, ICD implantation is performed without defibrillation testing (DT). OBJECTIVES: To determine the current frequency of DT, the risks associated with DT, and to understand how physicians select patients to have DT. METHODS: between January 2007 and July 2008, all patients in Ontario, Canada who received an ICD were enrolled in this prospective registry. RESULTS: a total of 2,173 patients were included; 58% had new ICD implants for primary prevention, 25% for secondary prevention, and 17% had pulse generator replacement. DT was carried out at the time of ICD implantation or predischarge in 65%, 67%, and 24% of primary, secondary, and replacement cases respectively (P = <0.0001). The multivariate predictors of a decision to conduct DT included: new ICD implant (OR = 13.9, P < 0.0001), dilated cardiomyopathy (OR = 1.8, P < 0.0001), amiodarone use (OR = 1.5, P = 0.004), and LVEF > 20% (OR = 1.3, P = 0.05). A history of atrial fibrillation (OR = 0.58, P = 0.0001) or oral anticoagulant use (OR = 0.75, P = 0.03) was associated with a lower likelihood of having DT. Age, gender, NYHA class, and history of stroke or TIA did not predict DT. Perioperative complications, including death, myocardial infarction, stroke, tamponade, pneumothorax, heart failure, infection, wound hematoma, and lead dislodgement, were similar among patients with (8.7%) and without (8.3%) DT (P = 0.7) CONCLUSIONS: DT is performed in two-thirds of new ICD implants but only one-quarter of ICD replacements. Physicians favored performance of DT in patients who are at lower risk of DT-related complications and in those receiving amiodarone. DT was not associated with an increased risk of perioperative complications.

Characterization of cardiac brain natriuretic peptide release in patients with paroxysmal atrial fibrillation undergoing left atrial ablation.

BACKGROUND: Paroxysmal atrial fibrillation (PAF) is associated with elevated levels of brain natriuretic peptide (BNP). The exact cardiac source and implications of this are currently unknown, as are the effects of left atrial ablation on cardiac BNP release. We sought to investigate BNP levels at different cardiac sites in PAF patients before and after left atrial ablation and compare these with a non-atrial fibrillation control cohort. METHODS AND RESULTS: Twenty PAF patients (52+/-10 years, 70% men; left ventricular ejection fraction, 55+/-3%) undergoing ablation were studied, BNP levels were measured at different cardiac sites before and after ablation and compared with a control cohort undergoing ablation for left lateral accessory pathways (10 patients, 41+/-11 years; left ventricular ejection fraction, 55+/-4%). In both cohorts, the coronary sinus BNP levels were the greatest. The PAF cohort had significantly greater BNP levels than the control cohort at all sites before and after ablation. Ablation of the left atrium was associated with a significant decrease in coronary sinus BNP levels (P=0.05) and transcardiac BNP gradient (P=0.03). This was not observed in the control cohort. CONCLUSIONS: BNP levels are elevated in PAF, with the highest levels in the coronary sinus. Ablation of the left atrium was associated with an immediate decrease of BNP levels, implicating this as the source.