Medtronic CEO Omar Ishrak was recently asked about how patients younger than retirement age are becoming more important to the future of the medical technology industry. Ishrak wasn’t ready to draw such distinctions.

“All of our patients are important to our future,” he said. “The vast majority of what we do is for Medicare patients.”

Most med-tech executives acknowledge that a rising number of nonelderly patients are turning to medical devices as treatments expand for a variety of ailments. But the elderly market remains critical for med-tech firms.

Fridley-based Medtronic makes more than half its revenues from heart rhythm and cardiovascular devices. Three-quarters of those receiving pacemakers and defibrillators are older than 65. That is unlikely to change much as heart disease hits aging Americans.

But device use among different age groups is shifting. In 2000, for example, an estimated 67 percent of all knee replacements were performed on patients 65 and older. By 2010, only 56 percent were elderly.

The Advanced Medical Technology Association (AdvaMed), the industry’s leading trade group, expects the elderly market to expand as baby boomers enter their senior years. “The number of people over 65 is going to increase in the next 20 years,” said David Nexon, AdvaMed’s senior executive vice president.

AdvaMed also predicts “explosive growth” in international sales as a middle class capable of purchasing orthopedic, cardiovascular and other products expands in India, China and Brazil.

Even the critical issue of device durability is not just a concern of the young, said Dr. Kenneth Stein, senior vice president and chief medical officer for Boston Scientific’s Cardiac Rhythm Management Division.

“Patients who are older are living much longer. Even within the Medicare population, defibrillator recipients will live eight, 10, 12 years after they get their implant,” he said. “In the early days ... we never thought patients would outlive their first device.”

James Walsh and Jim Spencer