(Reuters) - Shares of MyoKardia Inc hit a record high on Monday after the company said its experimental drug for an inherited heart disease met the main goal in a small mid-stage study.

Data on 10 patients showed that the drug, mavacamten, induced a statistically significant improvement in blood flow and aerobic capacity in patients with obstructive hypertrophic cardiomyopathy - a common cause of sudden cardiac arrest in young people, including athletes.

The condition occurs when heart muscle cells enlarge and can thicken ventricles walls, usually the left ventricle, according to the American Heart Association.

“The study results are much better than what most investors had anticipated or expected,” Wedbush Securities’ analyst David Nierengarten told Reuters.

Data announced on Monday came from the first group of patients of the study. A second group will get a smaller dose of the drug, and that data is expected in early 2018, the company said. The drug is being developed in collaboration with France’s Sanofi.

MyoKardia also said it would seek feedback from the U.S. Food and Drug Administration on the design of a key study, which could potentially reduce the developmental timeline for the drug.

The planned number of between 200 and 250 patients for the pivotal study is smaller than previously anticipated, Nierengarten added.

This news provides “added comfort on the emerging profile of mavacamten and helps to de-risk the overall MYOK story,” Credit Suisse’s Vamil Divan said in a client note.

Divan also raised his probability of mavacamten’s success to 75 percent from 40 percent, and lifted his price target on the stock by $20 to $45.

MyoKardia’s shares, which hit a record high of $32.30 earlier in the day, were up nearly 85 percent in afternoon trading.