The TOPCAT study followed the effect of spironolactone on a chronic heart failure with a preserved left ventricular ejection fraction. The study did not find any impact on the primary goal of the study, i.e. a combination of cardiovascular mortality, managed cardiac arrest or hospitalization rate for heart failure treatment. The only finding of the study was the decrease in hospitalization rates for a heart failure. A post hoc analysis, however, identified a significant difference between patients from the Americas (USA, Canada, Argentina, Brazil) on the one hand and those from Russia/Georgia on the other. The differences were rather striking. Whereas the former manifested a significant reduction in the incidence of the primary goal, i.e. cardiovascular mortality and hospitalization with heart failure through treatment with spironolactone, the incidence of all clinical events was considerably lower in Russia/Georgia and no impact of spironolactone at all on any of the goals was identified regarding the patients from Russia/Georgia. This post hoc analysis therefore suggested a possible therapeutic effect of spironolactone in the Americas, as well as in the populations of similar characteristics. Most studies accept a definition only based on the heart failure with a preserved left ventricular ejection fraction. The study points to the need to further elaborate this definition which also has to consider changes of the left ventricular diastolic function when defining a diastolic heart failure.