Visual Abstract - Follistatin-Like 1 Regulates Hypertrophy in Heart Failure With Preserved Ejection Fraction: 10.1016/j.jacbts.2016.04.002

• Fstl1, also known as transforming growth factor-β–stimulated clone 36, is an extra-cellular glycoprotein implicated in the pathophysiology of cardiac disease.

• Fstl1 acts in a noncanonical manner relative to other follistatin family members, but its functions remain poorly understood.

• Circulating Flst1 levels are increased in humans with chronic stable HFpEF.

• Fstl1 treatment modulates cardiomyocyte hypertrophy in vitro and in vivo.

• Cardiac myocyte deletion of Fstl1 worsens the HFpEF phenotype in mice.

• These studies indicate that Fstl1 may be therapeutically effective in HFpEF by modulating cardiac hypertrophy and improving parameters of diastolic dysfunction.