Management of Cardiac Amyloidosis - Episode 4
John L. Berk, MD: Ron, when in your practice are heart biopsies warranted, and are there undue risks?
Ronald Witteles, MD: Building on what Maz was saying, first, I want to emphasize that for AL [light chain] amyloidosis, it is a diagnosis that can only be made by biopsy. Now it doesn’t have to be a cardiac biopsy as Maz was saying. If you have proven AL amyloidosis, usually proven by MASS SPECT [mass spectrometry], your biopsy sample, and you have clear indications that there’s cardiac involvement by imaging, there’s certainly no need to biopsy the heart any more than there’s the need to biopsy the kidneys in somebody where you’ve proven cardiac amyloidosis, to prove that they have it there.
Remember that once you’ve made a diagnosis of systemic AL amyloidosis, there’s almost always a treatment indication with chemotherapy or other therapies as we’ll discuss later. So, in terms of changing what you’re going to do, yes it’s nice to know for sure if they have cardiac involvement, but the real question up front is, do we need to get them started on therapy or not? Now that gets somewhat into the choice of where you’re going to biopsy. While you can definitely find AL amyloid deposits in other places like a fat pad biopsy or sometimes in the bone marrow for somebody who has underlying AL amyloid of this, you can often miss it. You’ll find it more with AL than transthyretin in other places, but you can still miss it there. I would urge everybody who is viewing this to think of AL amyloidosis, particularly cardiac AL amyloidosis, as a near emergency to get people started on treatment. The disease can progress very quickly, and as we’ll talk about later, there are very effective therapies that we have available with it. But you have to get them started on people before they’ve had particularly too much cardiac damage.
So, in our practice at Stanford, we generally biopsy the clinically involved organ, which is most commonly the heart, to get a diagnosis quickly. Unlike many other infiltrative diseases, you approach a sensitivity and specificity of 100% if you biopsy the clinically involved organ. It’s very different in something like sarcoid, where you could biopsy the heart and more commonly than not, you’ll miss it. So that’s where we generally go. It’s reasonable to first go, say, for a fat pad biopsy, but only if you can do so very quickly and only if you’re going to follow it up very quickly with the biopsy of the clinically involved organ.
In terms of how risky a biopsy is, in good hands, the risks are really exceptionally low. These are very thick hearts almost by definition, so the main risk of perforation is really quite low. If these patients are being seen at a referral center, and I would say for AL amyloidosis, I would strongly urge getting patients to a referral center if at all possible. There are going to be good people with the technical skills, and you’re talking about a risk of complications that should really be far less than 1%.