There are no approved treatments for patients who have heart failure with preserved ejection fraction (HFpEF), a condition that accounts for about 50 percent of all heart failure. Therefore many physicians turn to medications designed for other types of heart disease to treat the symptoms of HFpEF.
Now, a recent study co-authored by Northwestern Medicine investigator Sanjiv Shah, ’00 MD, shows that HFpEF patients are actually less active when receiving a commonly prescribed nitrate medication thought to improve their exercise capacity and relieve shortness of breath.
It was not previously known how the drug, isosorbide mononitrate, affected symptoms for this subset of patients.
“In this type of heart failure, the overall squeezing function of the heart is normal but the heart is abnormally stiff. There are several additional abnormalities of the heart, blood vessels, kidneys and skeletal muscle in HFpEF that cause shortness of breath and fluid retention,” Shah said. “We found that nitrates did not help to improve symptoms or exercise capacity for patients with HFpEF who are limited in their activities.”
Shah is the Northwestern site principal investigator of the Heart Failure Clinical Research Network, which conducted the double-blind, multicenter trial. The study included 110 patients who randomly received the drug or a placebo over six weeks.
“Because we have the first and largest dedicated HFpEF program in the world, we were able to enroll the most patients of any other center,” Shah said.
Study participants wore two accelerometers – devices that resemble a highly accurate version of a Fitbit – on a belt around their hips at all times throughout the duration of the trial.
“The accelerometers provided the best outcome data for the trial, clearly showing that as the dose of nitrates went up, physical activity measured in number of steps went down in a linear fashion,” Shah said.
The trial’s results indicate that most patients with HFpEF should not take nitrates.
“This study highlights the importance of testing treatment in a rigorous fashion before simply extrapolating their use from other forms of heart failure to HFpEF,” said Shah, who is currently investigating novel medications and devices to help patients with this type of heart failure.
Earlier this year, he published a study that classified three distinct categories of HFpEF, a step that enables investigators to pursue more tailored treatments for patients.
This study was supported by the National Heart, Lung, and Blood Institute.