Hopkins study supports use of CT scan of heart

November 27, 2008|By Stephanie Desmon | Stephanie Desmon,stephanie.desmon@baltsun.com

Advanced CT scans that cardiologists have been slow to embrace are nearly as effective as the invasive and expensive surgical methods typically used to diagnose coronary blockages, according to new research out today by Johns Hopkins doctors.

But the findings aren't putting to rest the question of whether scanning the heart with computed tomography can be a suitable alternative to inserting a cardiac catheter when assessing patients with chest pains.

Instead, the debate is only intensifying over whether CT scans, widely used on many other parts of the body, should be used in cardiac patients and whether the financial cost and radiation are worth it.

"I think [the study] is overly optimistic about CT angiography," said Dr. Steven E. Nissen, a cardiologist at the Cleveland Clinic. "In the real world, as opposed to in a carefully designed study, CT angiography does not perform as well as was reported in this study."

In fact, the study's authors caution that they do not believe CT scans can replace catheterization in all cases.

At issue is whether doctors should send a patient in for catheterization, a proven test that does hold some risk as a small tube is inserted into the groin area and threaded up to the heart. It is a costly procedure that requires sedation, an X-ray and a few hours in recovery. The study suggests doctors might consider using the less invasive CT scan, which involves higher doses of radiation and is not proven to be equally effective.

Some worry that instead of saving money by replacing some of the 30 percent of catheterizations that turn out to be unnecessary, CT scans will just add a layer of expense. If doctors find a blockage on CT, patients usually will have to proceed to the surgery so a stent or a balloon can be inserted to open up arteries.

The Hopkins-led study is published today in the New England Journal of Medicine. It is the first to demonstrate on a large scale - 291 patients at nine hospitals in seven countries - that CT is effective at evaluating the heart, an organ difficult to take pictures of because it is in constant motion.

The study found that CT scans, which are essentially high-quality, three-dimensional X-rays, produced the same results as catheterization 93 percent of the time.

The authors conclude, however, that the scans "cannot replace conventional coronary angiography at present."

"We aren't at 100 percent," explained Dr. Julie Miller, a Hopkins cardiologist and the study's lead investigator. "Perhaps that's a high standard, but because it's so important to make sure the patient does or does not have a blockage, we can't say it's good enough to replace catheterization."

Still, she said, the study shows that CT and catheterization are equally useful in predicting the need for cardiac bypass surgery or angioplasty to restore blood flow.

And Miller thinks the heart CT can be better than other noninvasive tests such as stress tests or echocardiograms at diagnosing certain heart problems.

"We will begin to see the use of CT more as a first-line test in patients with chest pain in whom you suspect coronary artery disease," Miller predicted.

Dr. Kim Allen Williams, director of nuclear cardiology at the University of Chicago, is also a fan of the heart CT. "It's a tremendous test when applied to the right kind of people," he said.

But he doesn't think Miller's research will lead to more widespread use of the test, just the opposite.

Williams fears that the conclusions of the study - and an accompanying critical editorial - will actually mean fewer patients will be scanned because medical insurers, who have been reluctant to cover the unproven procedure, will have even more ammunition to justify refusing to pay for it.

Even though the study showed CT is 93 percent effective, by saying CT is not yet a replacement for conventional angiography, he said, "it's going to change the way payers look at it. That's what everyone is going to remember.

"They're looking at anything to try to improve the bottom line of their underwriting," said Williams, a spokesman for the American College of Cardiology who was not involved in the study.

Robert Mumma was - as a patient. For years, Mumma's doctors had worried about the health of his arteries. He had high cholesterol and a family history of heart trouble, and his doctors, worried about some test results, wanted him to undergo a catheterization.

He refused. A friend had died from a clot caused by the procedure, so "I'm aware of the downside of this," said the 62-year-old South Florida land developer, who spends part of his time in York County, Pa.

Then, his doctor recommended he have the CT scan done at Hopkins. In June 2007, Mumma did. The test, which revealed blockages, was bad news. Still, he refused a catheterization until that November when he started having chest pains. The CT, Mumma thinks, saved his life.

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