["Renin-angiotensin-aldosterone system activation may be involved in the pathogenesis of atrial arrhythmias in congestive heart failure (CHF). The effects of aldosterone blockade on atrial tachyarrhythmias have not been evaluated. This study's aim was to determine whether selective aldosterone blockade suppresses atrial tachyarrhythmia inducibility and modifies atrial electrical and/or structural remodeling in a canine model of rapid ventricular pacing (RVP)-induced CHF.", "Dogs were assigned randomly to treatment with oral placebo or eplerenone (50 mg/day) and divided into four groups: two sham-operated (no RVP) and two RVP groups. After 5 weeks of no RVP or RVP at 230 beats/min along with concurrent placebo or eplerenone treatment, dogs underwent electrophysiologic and echocardiographic studies. Sustained atrial tachyarrhythmia inducibility (>10-minute duration), atrial effective refractory periods (ERPs), systolic and diastolic function, and left atrial and left ventricular (LV) chamber sizes were assessed. Placebo-treated RVP dogs developed CHF with LV systolic and diastolic dysfunction, left atrial and LV enlargement, increased atrial ERPs, and inducible sustained atrial tachyarrhythmias. Eplerenone treatment in RVP dogs significantly suppressed sustained atrial tachyarrhythmia inducibility, nonuniformly prolonged atrial ERPs and attenuated LV diastolic dysfunction without modifying left atrial or LV dilation or ejection fractions in CHF. Isoproterenol (2-4 microg/min) reversed eplerenone's atrial antiarrhythmic and ERP prolonging effects in CHF. Eplerenone did not alter atrial ERPs in sham (no RVP) dogs without CHF."] Does selective aldosterone blockade suppress atrial tachyarrhythmias in heart failure?