More and more medical studies show that heart issues in women are not only underdiagnosed but should be treated differently.

A study Medtronic designed to test its Evolut TAVR (transcatheter aortic valve replacement), published this week in the New England Journal of Medicine, showed that the device could be the answer for many women with aortic stenosis.

Medtronic, whose operational headquarters is in Fridley, studied patients with small heart valves, called small aortic annuli. As a result, 87% of the patients in the study were women, atypical for a med-tech trail.

"We haven't been able to find a larger trial of just women," said Nina Goodheart, president of Medtronic's Structural Heart & Aortic unit.

Aortic stenosis is the narrowing of the aortic valve that blocks or slows blood flow from the heart. TAVR replaces the valve and is an alternative to surgery. When using the Evolut TAVR platform — or competitor Edwards Lifesciences' Sapien device — doctors select the size of the valve to be used in the procedure.

"Those patients are very often women," Goodheart said. "Women are underdiagnosed and undertreated, particularly women of color."

Dr. Ganesh Raveendran, chief of the cardiovascular division at the University of Minnesota Department of Medicine, said doctors have sometimes been wary of doing valve replacements for patients with smaller valves.

"This is important work. This gives us some scientific evidence that these patients with small annuli can be treated with TAVR without compromising outcomes," he said.

Severe aortic stenosis can be fatal if it is left untreated. Like many heart conditions, women are less likely to be referred for diagnosis and treatment compared with men. There is generally a lack of awareness among women of the risks of aortic stenosis as well.

"Cardiovascular disease is the number one cause of death for women in this country. Most women don't know that," said Dr. Laura Mauri, chief scientific, medical and regulatory officer for Medtronic. Mauri said that with its focus on women, the findings of the study can help address health care disparities.

Medtronic announced its findings last weekend at the American College of Cardiology Annual Scientific Session in Atlanta.

Goodheart told an investors and analysts that the findings will help Medtronic grow its business in the valve market.

"We've got a lot of populations to address," Goodheart said. "I believe we will see market share change."

Medtronic said that the global TAVR market is worth $6 billion and is growing in the high single- to low double-digits.

Dr. Manesh Patel, a member of the American Heart Association's board of directors and a cardiologist at Duke University, said the information from the study is important.

"This will hopefully allow more people to be treated with more confidence about how the patients getting TAVR will do," he said.

Dr. Howard Herrmann with the Perelman School of Medicine at the University of Pennsylvania, who helped design the 726-patient study, said the intent was to look at the Medtronic and Edwards valves, which are those most commonly used in the U.S. The study showed that Evolut and Sapien had similar results for clinical outcomes but the Medtronic device was found to be superior for valve function.

However, J.P. Morgan analyst Robbie Marcus said since Medtronic designed the study and chose the valves used, he is not as impressed in the results that put the Medtronic device above Edwards'.

"While the results read positive for Evolut, the [study] outcomes deviate significantly from what's seen in clinical practice and prior trial results for Sapien," said Marcus, who said it was the highlight of the ACC conference. For that reason, he does not expect a big shift between the two companies' market share for TAVRs.

However, Medtronic sees a growth opportunity, officials said. One reason: The company received Food and Drug Administration approval for the next generation of Evolut, the FX+, at the end of March. That means Medtronic expects the updated device to be released in the U.S. this summer.