Q&A: LVNC: A Rare, But Overdiagnosed Disease?

September 7, 2015

This Q&A series explores radiology’s role in overdiagnosis in a variety of conditions. Here, we discuss left ventricular noncompaction cardiomyopathy.

Overdiagnosis is commonly discussed in areas like breast imaging, where screening is widely conducted and media interest is high. While it’s under the radar for other diseases, it’s a big enough topic in the medical world to warrant a dedicated issue in Academic Radiology. Its August 2015 issue is devoted to overdiagnosis, a term used for disease that’s correctly diagnosed, but at the earliest stages when treatment may not be necessary and might even be harmful to the patient. This is in contrast to false positives, when the diagnostic test incorrectly indicates the possible presence of disease.

Overdiagnosis is more prevalent in modern times because the definition of disease has expanded, said Saurabh Jha, MBBS, assistant professor of radiology at the Hospital of the University of Pennsylvania, and guest editor of the Academic Radiology issue. “The rationale is the very intuitive concept that if we catch disease early on, we’ll avoid morbidity and mortality, that prevention is better than cure.”

Through screening, radiologists define the pathway to disease and are the gatekeepers of the technology often validating the diagnosis, since the gold standard of a diagnosis by pathology isn’t always an option.[[{"type":"media","view_mode":"media_crop","fid":"40967","attributes":{"alt":"Vinay Kini, MD","class":"media-image media-image-right","id":"media_crop_9159406028423","media_crop_h":"0","media_crop_image_style":"-1","media_crop_instance":"4252","media_crop_rotate":"0","media_crop_scale_h":"0","media_crop_scale_w":"0","media_crop_w":"0","media_crop_x":"0","media_crop_y":"0","style":"float: right;","title":"Vinay Kini, MD","typeof":"foaf:Image"}}]]

With more advanced technology, radiologists can see deeper into structures in the body, discovering new (but often innocuous) abnormalities. Another reason for a growth in overdiagnosis is cultural. The division between “diseased” and “healthy” is arbitrarily set.

“There’s always going to be disputes about where the boundary takes place,” said Jha, with nothing magically happening at that threshold where disease is defined. However, in the United States, that threshold is often set at a place where doctors won’t miss any disease, erring on the side of overdiagnosing a person who doesn’t need treatment. “We live in an extremely risk averse environment.”

This Q&A series looks at a number of diseases that may be overdiagnosed in the United States, where we might be “treating health as opposed to solving sickness,” according to Jha.

Left ventricular noncompaction cardiomyopathy is a problem because the disease was initially rare, then thought to be less rare. “Diagnosis is almost entirely based on imaging,” said Jha. “Once a disease is defined, people ask us to rule out the disease. If it meets the criteria, you can’t rule it out, and lots of people will meet the definition.” Here is our Q&A with Vinay Kini, MD, Cardiovascular Fellow at the Hospital of the University of Pennsylvania.

Please explain what LVNC is.

It’s basically a disease where the inner layer of the heart, the myocardium, doesn’t compact correctly during fetal development. There are these wavy layers of heart muscle (in the left ventricle) that extend to the inside of the heart and cause several problems as the patient grows older, like heart failure, stroke, and arrhythmia. The spectrum of disease is varied. It’s a very rare disease that we’re still learning a lot about. We don’t know how often this happens. We don’t even know how many patients have this disease in the U.S. We know that patients with the more severe forms of the disease tend to suffer those symptoms.

How is the diagnosis of LVNC made?

These days generally the diagnosis is made by an imaging test. In general, most of those instances will be done on asymptomatic patients. Essentially what you’re looking for on the test, whether an echocardiogram or an MRI, is the classic picture of the wavy layers of the heart extending into the heart cavity. Based on some very small studies, we’ve developed some thresholds for labeling someone with this disease based on the ratio of the noncompacted to the compacted myocardial tissue.

How did this threshold come about?

There was one small study in 2005 that used MRI and two small studies in the early 2000s that used echocardiograms. This is all that it’s been based on. The scientists, who developed this threshold, developed it with small numbers of people with very specific forms of the disease. Subsequently, when these thresholds were tested on larger populations with different sexes and racial groups, the thresholds didn’t hold up at all. In one study of the most diverse groups of patients, over 40% of asymptomatic healthy people met one of the major criteria for noncompaction.

No single medical society or writing group has developed criteria for the diagnosis of left ventricular noncompaction cardiomyopathy. That’s a reflection of how poorly this disease is understood and how poorly we know how to diagnose patients with the disease.

What are other diagnostic criteria?

In terms of imaging, the ratio is the main thing. You’re also looking for left ventricular ejection fraction, basically a weak heart, and other associated findings that go along with heart failure. The problem really is that the imaging test is asked to make this diagnosis when, in reality, there should be some suspicion of the diagnosis to begin with. That includes symptoms, such as symptoms of heart failure, stroke, arrhythmia, or a family history of the disease.

What is your message to cardiologists and radiologists? How can they reduce overdiagnosis?

There are a couple of things radiologists and cardiologists who read these can keep in mind. One thing that’s very helpful is if you’re going to include the possibility of the diagnosis in the report, it can be very helpful to report that this is a normal finding in a significant percentage of patients, and that this finding should be taken in clinical context. So if a patient otherwise doesn’t exhibit other symptoms of LVNC, they probably should not be treated for it. I think putting it in the context that it’s not a perfect test and that many other normal people have this finding is the single most important thing radiologists and cardiologists can do. From the clinician side, the cardiologist who ordered this test needs to be aware that the imaging test in isolation should not make this diagnosis.

What are the dangers of falsely labeling someone with this disease who actually doesn’t have it?

The dangers are two main things. The first is over-testing. That means that the patients who have a label or possible diagnosis of noncompaction, or are definitely diagnosed, get all sorts of follow up testing. Many of these tests don’t have a lot of negative consequences, maybe it’s an imaging test repeated every year. But some could expose the patients to radiation. The more concerning thing is that patients who are mislabeled with this disease are at high likelihood of being treated with medications, which can include blood thinning medications like Warfarin, which is not benign. It increases the risk of bleeding, which can include severe bleeding into the head or bowels. In addition, people with noncompaction are at higher risk for ventricular arrhythmia, which can be treated with an implantable defibrillator. That procedure is not without consequences. Additionally those patients can be at risk for getting inappropriate shocks.