Top heart doctors and researchers have a simple reaction to President Donald Trump's proposed 20 percent cut to the budget of the U.S. National Institutes of Health: fear that research that results in life-saving drugs will deal a crippling blow.

As drugmakers shift focus to more lucrative areas, such as oncology and rare diseases, fewer heart drugs in their pipelines means NIH-funded research may be more important to cardiology than ever, doctors at the recent American College of Cardiology meeting said.

Despite major advances that have helped patients live longer, healthier lives, heart disease remains the world's No. 1 killer.

Top heart doctors and researchers at the ACA meeting used words like "chilling" and "catastrophe" to describe their reaction to the proposed $5.8 billion cut to the NIH budget.

They noted that the Nobel Prize-winning scientists whose discovery led to development of the world's most successful, widely used heart drugs were funded by the NIH, as were countless studies and research that has changed medical practice and enhanced the lives of millions.

"There are trials that we have to do that will never be funded by drug companies. We rely on NIH," said Dr. Leslie Cho, head of preventive cardiology at Cleveland Clinic.

A prime example: the government-funded landmark Sprint trial that found more aggressive treatment with generic blood pressure medicines dramatically cut heart failure and risk of death in adults aged 50 and older.

Interviews with about a dozen top cardiologists at the ACC meeting found unanimous condemnation of the proposed cuts amid fear they will halt important work and disenfranchise a new generation of researchers.

"I'm a little concerned that there hasn't been a complete eruption that the NIH is being targeted for such substantial cuts. This is a landmine waiting to explode," said Dr. Clyde Yancy, a former American Heart Association president.

"Laboratories will be shut down; personnel would be released; ideas would be left incomplete; proposals would go unaddressed. We just can't afford to have the pace of scientific discovery slowed down like this," said Yancy, from Northwestern University Feinberg School of Medicine in Chicago.

Dr. Steven Nissen, chief of cardiology at Cleveland Clinic, pointed to the work of Michael Brown and Joseph Goldstein that eventually gave the world statins, such as Pfizer's Lipitor, the cholsterol-lowering drugs which prevent heart attacks. Early NIH-funded research laid the groundwork for a wide range of big-selling drugs produced by the pharmaceutical industry.

"How many millions of heart attacks and lives have been changed by that. If you don't fund the Browns and Goldsteins of the world, where do the next discoveries come from?" asked Nissen.

Dr. Andrew Kates runs the cardiology fellowship training program at Washington University in St. Louis.

"I know the struggles that our fellows face looking for career development awards and that's all NIH-funded grants. So the pipeline that we need for future researchers will be at significant risk," Kates said. "We all need to be concerned."

To be sure, the real budgeting power lies with Congress, which could reject NIH cuts.

"Aside from defense and vets, NIH is one of the most universally loved programs on Capitol Hill," said Capital Alpha Partners analyst Rob Smith.

But Congress is controlled by the president's party and there is no guarantee Republicans will stand against Trump or to what extent.

Dr. Patrick O'Gara, director of clinical cardiology at Brigham and Women's Hospital in Boston and a former ACC president, said massive NIH cuts would hurt local economies.

"That will eventually trickle down to the workers who are able to enjoy access to good jobs that have been driven by this biotechnology juggernaut, much of which relates to the level of research that can be accomplished," O'Gara said.

"I'm hopeful that this is just an opening gambit and Congress ... will look at things differently," he added.

ACC President Dr. Mary Walsh, director of heart failure and transplantation programs at St. Vincent Heart Center in Indianapolis, called for fierce opposition to the proposed cuts.

"All of medicine and all of investigation need to make our voices heard," she said. "This could become a unifying theme. Science matters!"