New Study Shows Myqorzo Helps Patients With Nonobstructive HCM Feel and Function Better

Nonobstructive hypertrophic cardiomyopathy (HCM) is a common heart condition that can cause significant symptoms and complications, yet there's currently no approved medication that treats it directly. A major new study looked at whether a drug called Myqorzo (aficamten) could help patients with this form of HCM feel better and function better in daily life. The results were presented at a major European cardiology conference and published in The New England Journal of Medicine.

The study included 517 adults with symptomatic nonobstructive HCM. Participants were randomly assigned to receive either Myqorzo or a placebo (an inactive pill) for up to 72 weeks, with no one, including researchers, knowing who received which treatment until the study ended. The average participant was 55 years old, and just over half were women. Patients started on a low dose of Myqorzo, and doctors used heart ultrasounds to safely increase the dose over time if needed.

What the Study Found

Researchers tracked two main things: how well patients could exercise, and how patients themselves felt day to day, based on their symptoms and overall quality of life.

At 36 weeks, patients taking Myqorzo reported meaningfully better symptoms and quality of life than those on placebo. They also saw a real improvement in their exercise capacity, meaning their bodies could use oxygen more efficiently during physical activity, a sign the heart was pumping more effectively. Patients on placebo, meanwhile, saw little to no improvement in either measure over the same period.

"ACACIA-HCM is the first-ever positive clinical trial in nonobstructive HCM," said Stephen Heitner, M.D., Cytokinetics' chief medical officer, calling the results both scientifically strong and meaningful for patients living with this form of the disease.

Broader Benefits Seen Across the Board

Researchers also looked more broadly at how Myqorzo affected the heart itself, beyond just symptoms and exercise. They examined five different areas: exercise ability, the heart's physical structure, blood markers of heart stress, how well the heart relaxes between beats, and overall symptom burden. Patients taking Myqorzo showed meaningful improvement in all five areas compared to those on placebo. More than half of patients on Myqorzo improved in at least three of these areas, compared to only approximately 1 in 8 patients on placebo, suggesting the drug's benefits extend well beyond what a single measurement can capture.

Safety and Side Effects

Overall, Myqorzo was reasonably well tolerated. Some patients experienced more serious side effects on the drug than on placebo, and a small number needed to stop treatment early due to side effects. In a minority of patients, the heart's pumping strength temporarily dipped lower than normal while on Myqorzo; this was closely monitored, and most of these patients were able to continue treatment at the same or a lower dose. A small number of patients developed signs of heart failure while adjusting to the medication, but these cases responded well to short-term treatment with a water pill (diuretic) and occurred early in treatment, mostly within the first three months.

What Happens Next

Most patients who took part in the study have chosen to continue taking Myqorzo through an extended follow-up study, according to Ahmad Masri, M.D., M.S., director of the Hypertrophic Cardiomyopathy Center at Oregon Health & Science University and the study's lead researcher. Based on these encouraging results, Cytokinetics plans to formally ask the U.S. Food and Drug Administration to approve Myqorzo for this patient population later this year. Myqorzo is already approved for a different, more common form of HCM.