AIMS: The aims of this study were to explore phenotypes of heart failure with preserved ejection fraction (HFpEF) and evaluate differential effects of spironolactone treatment. METHODS AND RESULTS: A swap-stepwise algorithm was used for variable selection. Latent class analysis based on 10 selected variables was employed in a derivative set of 1540 patients from the TOPCAT trial. Cox proportional hazard models were used to evaluate the prognoses and effects of spironolactone treatment. Three phenotypes of HFpEF were identified. Phenotype 1 was the youngest with low burden of co-morbidities. Phenotype 2 was the oldest with high prevalence of atrial fibrillation, pacemaker implantation, and hypothyroidism. Phenotype 3 was mostly obese and diabetic with high burden of other co-morbidities. Compared with phenotype 1, phenotypes 2 (hazard ratio [HR]: 1.46; 95% confidence interval [CI]: 1.14-1.89; P = 0.003) and 3 (HR: 2.35; 95% CI: 1.80-3.07; P < 0.001) were associated with higher risks of the primary composite outcome. Spironolactone treatment was associated with a reduced risk of the primary outcome only in phenotype 1 (HR: 0.63; 95% CI: 0.40-0.98; P = 0.042). CONCLUSIONS: Three distinct HFpEF phenotypes were identified. Spironolactone treatment could improve clinical outcome in a phenotype of relatively young patients with low burden of co-morbidities.