Cikes M, et al. - The relationship between atrial fibrillation (AF) and outcomes of the TOPCAT (Treatment of Preserved Cardiac Function Heart Failure With an Aldosterone Antagonist) trial was explored in order to see if AF modified the treatment response to spironolactone and if spironolactone influenced post-randomization AF. In patients with heart failure with preserved ejection fraction (HFpEF), an association of AF at enrollment with increased cardiovascular risk was seen. Spironolactone had no influence on post-randomization AF, though it was associated with an increased risk of morbidity and mortality.

Methods

• The 1,765 patients enrolled in TOPCAT in North and South America, were split into three groups (no known AF, history of AF without AF at enrollment, and AF found on the electrocardiogram (ECG) at enrollment).
• In all groups, outcomes and treatment response to spironolactone were assessed and the association between post-randomization AF and outcomes in patients free of AF at baseline was determined.
• A composite of cardiovascular mortality, aborted cardiac arrest, or heart failure hospitalization was the primary outcome of the TOPCAT trial.

Results

• A history of AF (18%) or AF on ECG at enrollment (25%) was reported for a total of 760 patients (43%).
• Researchers noted the highest adjusted risk in association with AF at enrollment (primary outcome, hazard ratio: 1.34; 95% confidence interval: 1.09 to 1.65; p = 0.006; and an increased early risk of secondary outcomes).
• The beneficial treatment effect of spironolactone was not influenced by the history of AF or AF at enrollment.
• Post-randomization AF was observed in 6.3% of patients; spironolactone treatment did not influence this incidence.
• However, post-randomization AF seemed correlated with an increased early risk of the primary outcome (hazard ratio: 2.32; 95% confidence interval: 1.59 to 3.40; p < 0.0001) and secondary outcomes.