WESTON, Fla. -

Many people are undergoing stress tests to see how healthy their heart is, but the tests have benefits and limitations.

Robert Rubin is no stranger to the dangers of heart disease, which is the leading cause of death in the United States. His father had a heart attack at 40-years-old and Rubin himself was diagnosed with diabetes at 50-years-old.

"Those two factors led me to seek out a cardiologist and start doing testing, doing stress tests every year," said Rubin.

Rubin was reassured by stress tests that showed no signs of heart disease, but after suffering chest pains last fall, he learned one of his arteries was 99 percent blocked.

"If I take the stress test and it shows nothing, how sure of that can I be," said Rubin.

A stress test is a non-invasive way to look at the function of the heart.

"Very often patients will say, 'How do my arteries look?' A stress test doesn't look at the arteries. It looks at the response of the heart to exercise," said Dr. Howard Bush with Cleveland Clinic Florida.

Mechanical stress tests, where a patient runs on a treadmill while hooked up to an EKG, pick up heart disease 85 percent of the time. Stress tests that implement imaging techniques and exercise are 90 to 95 percent accurate.

"But we're in an era of cost containment, so the insurance company may resist it," said Bush. "In other words, start with a standard test and see how well they do with that and then if there's further questions, we can go further."

Bush said age is not a factor when it comes to determining who should undergo a stress test.

"If you're a 30-year-old diabetic who smokes with a bad family history, it's probably time for a stress test," said Bush. "On the other hand, if you're a 70-year-old that's fully active with no limitation, there's no reason why you need a stress test

Patients who cannot exercise can undergo a pharmacologic stress test, where medication is given to stimulate movement. Pharmacologic stress tests are 90 to 95 percent accurate.