Abstract 14922: Prognostic Value of Baseline BNP and NT-ProBNP and its Interaction With Spironolactone in Patients With Heart Failure and Preserved Ejection Fraction in the TOPCAT Trial

Abstract

Background: Plasma natriuretic peptides (NP) are helpful in the diagnosis of heart failure (HF) with preserved ejection fraction (HFpEF) and predict adverse outcomes. Levels of NP beyond a certain cut-off level are often used as inclusion criteria in clinical trials to ensure that the patients have HF, and to select patients at higher risk. Whether treatments have a differential effect on outcomes across the spectrum of NP levels is unclear. In the I-Preserve trial a benefit of irbesartan on all outcomes was only seen in HFpEF patients with low but not high NP levels. We hypothesized that in the Treatment of Preserved Cardiac Function Heart Failure with an Aldosterone Antagonist (TOPCAT) trial, spironolactone might have a greater benefit in patients with lower NP levels. Methods and Results: BNP (n=468) or NT-proBNP (n=400) levels were available at baseline in 868 patients with HFpEF enrolled in the natriuretic peptide stratum (BNP ≥100 pg/mL or an NT- proBNP ≥360 pg/mL) of the TOPCAT trial. In a multi-variable Cox regression model, that included age, gender, region (Americas vs. Russia/Georgia), atrial fibrillation, diabetes, eGFR, BMI and heart rate, higher BNP or NT-proBNP as a continuous, standardized log-transformed variable or grouped by terciles (see Figure for BNP & NT-proBNP tercile values) was independently associated with an increased risk of the primary endpoint of cardiovascular mortality, aborted cardiac arrest, or hospitalization for heart failure (Figure-1). There was a significant interaction between the effect of spironolactone and baseline BNP or NT-proBNP terciles for the primary outcome (P=0.02, Figure-2), with greater benefit of the drug in the lower compared to higher NP terciles. Conclusions: The benefit of spironolactone in lower risk HFpEF patients may indicate effects of the drug on early, but not late higher-risk stage of the disease. These findings question the strategy of using elevated NP as a patient selection criterion in HFpEF trials.