Ep 151: A 55-Year-Old with Cardiac Amyloid
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This is Katarina Heidhausen, Executive Editor of Harrison's Principles of Internal Medicine. Harrison's Pod Class is brought to you by McGraw-Hill's Access Medicine, the online medical resource that delivers the latest content from the best minds in medicine. And now, on to the episode. Hi, everyone. Welcome back to Harrison's Pod Class. We're your co-hosts. I'm Dr. Kathy Handy. And I'm Dr. Charlie Wiener, and we're joining you from the Johns Hopkins School of Medicine. Welcome to today's episode about a 55-year-old with cardiac amyloid.

Kathy, today's patient is a 55-year-old woman with trans-thyretin amyloid cardiomyopathy who has admitted to the coronary care unit with decompensated heart failure. Over the last year, her ejection fraction has consistently been recorded at less than 20% and her function has declined. Over the last few weeks, she's become more physically limited and her weight has increased 15 pounds. She's now admitted for diuresis and inpatient inotrope treatment.

All right, are we going to talk about cardiac amyloid today? Good topic. No, we're actually going to go in a slightly different direction, but let's put that on for a future episode. The question I'm going to ask is about cardiac transplantation. Okay, well, cardiac transplantation is coming up on its 60th birthday soon, since the first human cardiac transplant was performed in 1967 by Christian Bernard.

Since then, over 150,000 patients have undergone cardiac transplantation with a one-year survival over 80% and a conditional survival of almost 15 years if the recipient survives the first year after transplant. Wow, that's amazing outcomes for a group of patients with an otherwise terrible prognosis. What's our question about today? So the question is asking, which of the following statements regarding cardiac transplantation is true?

Option A says, after cardiac transplantation, atropine is not effective in treating post-operative bradycardia. Option B, cardiac allograft vasculopathy is the leading cause of mortality in the first year after cardiac transplantation. Option C, cardiac amyloid is a contraindication to transplantation. Option D, inpatients on active circulatory support are not candidates for cardiac transplantation.

Option E is multi-parous women have an improved survival over nulliparous women or men. All right, I'm going to take them a little bit out of order. First off, our patient with cardiac amyloid and on inpatient inotropic therapy is a candidate for potential cardiac transplantation. Plus, her inpatient status would elevate, not decrease, her candidacy. Well, that's good news. Tell me more.

As with all solid organs, the demand for cardiac transplantation outstrips the availability of organ donors. Hence, attention to the optimal utility, the equitable allocation, and patient autonomy must dominate the decisions to identify and list candidates for transplantation.

In 2016, the International Society for Heart and Lung Transplantation updated their guide for listing patients to include the growing epidemiology of candidates who are suffering from congenital heart disease, restrictive and infiltrative cardiomyopathy, and that includes amyloidosis like our patient, and chronic infections and recipients such as Chagas disease. Okay, so cardiac amyloid is not a contraindication for transplantation. What about inpatient versus outpatient?

The allocation of donor hearts is based on one, the urgency of the clinical situation, two, the time spent on the waiting list, and three, the distance from the recipient center. Candidates who are hospitalized in critical status and require ECMO or temporary mechanical circulatory support devices to support both ventricles are given the highest urgency status.

and that's followed by those requiring daily invasive hemodynamic evaluation and IV inotropic therapy to maintain stability, or those with complications of a durable left ventricular assist device or LVAD. Others stable at home while supported by an LVAD or those able to ambulate and live at home receive a lower urgency status. Since our patient is admitted for inpatient inotropic therapy, she would be a higher priority than a more stable outpatient.

Okay, so we're taking this in a clinical sequence. Option A talks about postoperative tachyarrhythmias. So let's quickly review how the surgeon actually implants the new heart.

The most common contemporary operation is referred to as a bicaval orthotopic cardiac transplant, and that mimics the natural anatomic position. In this operation, the donor and recipient's superior and inferior vena cava are connected, as are the aortic and pulmonary great vessels. The left atrium of the recipient retains its roof, including the draining pulmonary veins, and the donor left atrium is then sutured to the retained atrial tissue.

This technique maintains function of the donor right atrium, important for governing early postoperative right heart output, and may prevent atrial arrhythmias. However, the recipient is left with a surgical denervation, and the allograft is not responsive to any physiologic sympathetic or parasympathetic stimuli.

Due to denervation, bradycardia in a cardiac allograft cannot be treated with atropine. Okay, so option A is true. Exactly. Okay, the last two options have to do with survival. Why are they false? Acute rejection is of great concern in the first months after transplant. We've made great strides with the use of postoperative combination immunosuppression, typically tacrolimus, mycophenolate mofetil, and prednisone.

Multiparous women are at higher risk of acute rejection and often augmented induction therapy. And finally, cardiac allograft vasculopathy? Cardiac allograft vasculopathy is a late, not an early, complication of cardiac transplantation. And what is cardiac allograft vasculopathy? It's an accelerated form of coronary artery disease that occurs in the allograft. Okay, so the teaching points from today's case are that cardiac transplant is amazingly successful with greater than 80% survival.

Patients with a variety of illnesses, including amyloidosis, are candidates. But take note that when the cardiac allograft is implanted, it is de-innervated, so will not respond to either vagal or sympathetic exogenous agents. And you can find this question and other questions like it in Harrison's self-review. And if you want to learn more about this, you can check out the Harrison's chapter on cardiac transplantation.

Visit the show notes for links to helpful resources, including related chapters and review questions from Harrison's, available exclusively on Access Medicine. If you enjoyed this episode, please leave us a review so we can reach more listeners just like you. Thanks so much for listening. ♪