Hemodynamic Response to Exercise in HFpEF Patients After Upregulation of SERCA2a

Overview

Heart failure with preserved ejection fraction or HFpEF, represents nearly 50% of all heart failure cases and is particularly common in the elderly. The disease has no current treatment options. Symptoms typically occur during exertion or exercise and is likely the result of increased cardiac and pulmonary congestion as a result of impaired diastolic function. Istaroxime is a novel activator of SERCA2a, an important regulator of calcium uptake within the myocyte. We will test the hypothesis that Istaroxime will improve diastolic function during exercise in HFpEF patients which in turn will reduce cardiac and pulmonary congestion.

About half of all elderly patients with a diagnosis of congestive heart failure have apparently normal systolic function, so called "heart failure with a preserved ejection fraction" or HFpEF. To date, no effective therapy for HFpEF has been found, in part because of failure to discern key pathophysiologic pathways. An extensive amount of pre-clinical work has identified that altered sarcoplasmic reticulum (SR) Ca2+ uptake, storage, and release play a major role in the changes in cardiac relaxation associated with aging, especially regarding sequestration of Ca++ by the sarcoplasmic reticular Ca++-ATPase (SERCA2a), which causes cardiac muscle relaxation by reducing cytosolic Ca++. Istaroxime is a relatively new drug that augments lusitropic function by upregulating SERCA2a activity in the heart. Because of the clear importance of slowed relaxation in HFpEF, and the evidence that depressed SERCA2a activity contributes to the slowed relaxation with aging, the proposed study may be establish the "impairment of SERCA2a" hypothesis as a mechanism of impaired relaxation in HFpEF subjects.