As the prevalence of HFpEF increases with the ageing population, especially in elderly women this project fully addressed the need for “New treatments for chronic, non-communicable diseases”, while taking the gender aspect into account. HFpEF differently affects men and women, and is typically associated with comorbidity. Sex also affected the outcomes, since women had a better overall prognosis. Our trial enrolled carefully phenotyped patients with significant co- morbidity and test a drug with potential pleiotropic effects likely to significantly affect this comorbidity. Indeed, in addition to LV remodelling and diastolic function, in 2 sub-studies, we evaluated the effect of mirabegron on endothelial function and NO bioavailability, as well as metabolism, thereby trying to correlate effects on remodelling with β3-mediated modulation of risk factors.
While the results are neutral in the conditions of our trial, this does not invalidate our original hypotheses; indeed, these deserve to be examined in subsequent trials with higher doses of mirabegron in patients with more severe phenotypes and for longer periods of treatment. Indeed, the abundance of the target, cardiac beta3 adrenergic receptors, is known to be higher in more advanced diseases than in patients selected in our trial. Also, more efficacy may be expected from newer, more potent beta3 agonists in development.
Altogether, our and future trials should provide new avenues for the treatment of a disease with a steadily increasing burden on the health care system and society. Contrary to heart failure with reduced ejection fraction (HFrEF), outcomes have not improved over the last decades, highlighting the need for new, effective therapies for this important syndrome.
Given the reassuring data on safety from our BETA3LVH trial, similar protocols with new agonists could be easily replicated in additional studies and lead to an extension of indication of "repurposed" urological drugs and so would lead to a quick impact for patients.