When Knowledge Creates Potential for Demand: MRI Detection of Silent MI’s.

Posted on | November 9, 2015 | Comments Off on When Knowledge Creates Potential for Demand: MRI Detection of Silent MI’s.

Mike Magee

In the November 10th issue of JAMA, devoted to cardiovascular disease, David Bluemke, NIH Director of Radiology and Imaging Sciences, and his team, revealed a set of findings certain to draw mixed reviews from health economists and policy professionals. It seems that quite a few more people than we had realized are walking around with scarred hearts (from myocardial infarctions in the past).

Now depending on whether you are generating a bill or paying for it, this is happy or sad news. But first a few facts from the study. The study involved 1,840 men and women, ages 45 to 84, from six US communities, and lasted a decade. The focus was on undiagnosed heart attacks. For these people, the symptoms were too mild or entirely absent to draw much attention. So they were ignored, and life fortunately went on.

Now this is not a new phenomenon. In fact, a group in 2002 checked out a population of heart attack patients, and reviewing their old ECG’s, determined that 20% had evidence that their previous heart attacks had gone undetected.

At the same time, experts have also been aware for some time that the ECG is not a perfectly sensitive test of heart muscle damage. In fact, smaller scars that result from limited episodes of ischemia caused by blocked cardiac arteries can be easily missed by the classic ECG. That is why, in this study, the NIH investigators turned up the dials and used enhanced MRI’s to look for scars – even small ones.

The group of patients all had one thing in common – they had complained of heart problems. And in response all received standard ECG’s and blood work during the ten year period. They appeared fine. Then, at the ten year mark, all received their MRI’s. The sensitive test found that 8% of them (146 people) had scarred hearts, and 78% of those weren’t aware of having ever had a heart attack. This included 13% of the males in the study and 2.5% of the females.

The incoming president of the American College of Cardiology, Richard Chazal, telegraphed a potential change in practice when he said of the study, “It’s almost like having looked at a petri dish with a magnifying glass, and then having the availability of a microscope. All of a sudden you can see things that you couldn’t see before.”

But the question is, Do we really want to know? Is this endpoint worth detecting? It’s pretty easy to predict what will happen next. Some doctors, including perhaps those with financial ties to imaging centers, will be doing many more enhanced cardiac MRI’s. Symptomless patients, especially those with great insurance or the financial means and an obsession about their own mentality, will be urgently requesting these exams. And at the end of the day, we will retrospectively, as with the PSA for prostate cancer, have to sort out whether knowing something adds or detracts from quality of life.