Ep 121: Patient with Advanced Heart Failure

This episode discusses recent advances in left ventricular assist devices and the clinical indications for this type of technological support.

Transcript

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[Dr. Handy] Hi, everyone. Welcome back to Harrison's Podclass. We're your co-hosts. I'm Dr. Cathy Handy. 

[Dr. Wiener] And I'm Dr. Charlie Wiener, and we're joining you from the Johns Hopkins School of Medicine. 

[Dr. Handy] Welcome to episode 121: a patient with advanced heart failure. 

[Dr. Wiener] Cathy, today we're entering a brave new world where I suspect neither of us is fully comfortable. 

[Dr. Handy] There are a few possibilities for that. 

[Dr. Wiener chuckles] Okay. Well, this one is transplant cardiology and suitability for left ventricular assist devices. 

[Dr. Handy] All right, we're going to have to start with some background then. As we've become better at treating heart failure, the engineers have also been working with clinicians to design clinically useful and durable forms of left ventricular support because we know that transplants are not always immediately available, unfortunately. Currently, all the implantable mechanical left ventricular circulatory support devices utilize continuous, not pulsatile like the normal heart flow. As the technology has improved, LVASs, which are the left ventricular assist devices, have evolved from short-term support as a bridge to recovery or to cardiac transplantation to the most frequent use today which is really permanent support for lifetime therapy. That's also called destination therapy. And sometimes these are implanted as what we consider a bridge-to-decision, which is sort of between those two options. 

[Dr. Wiener] You mentioned that the current LVASs are continuous flow. Give us a few words on the technology that drives them. 

[Dr. Handy] Yeah, and please don't push me on this, but they all utilize centrifugal flow, and the improvements over the last years have lessened the risk of thrombosis and hemolysis. The currently most often utilized system uses a frictionless, magnetically levitated pump that has reduced the risk of stroke. 

[Dr. Wiener] Okay, yeah, that's a long way from oncology but are there data to support the use of these LVASs or is this another example of we just do it because we can? 

[Dr. Handy] Yeah, there is some data behind it. The REMATCH trial in 2001 demonstrated a survival benefit and a quality of life improvement for patients that were not transplant candidates who received an LVAS. And this trial used older technology with higher complication rates than today's newer devices. More recent data from registry analyses show a median survival of over 50% at 4 years with currently available LVASs; however, long-term durability beyond 5 to 10 years still remains a question.

[Dr. Wiener] Great. Well, let's get to the question. The question asks, all of the following patients may be suitable candidates for consideration for a left ventricular assist device, or an LVAS, except? So there's going to be four patients who are suitable and one who's not. Patient A is a 33-year-old man with stress cardiomyopathy after the sudden death of his mother. Patient B is a 42-year-old woman with acute viral myocarditis who's in cardiogenic shock. Option C is a 55-year-old man with severe ischemic cardiomyopathy awaiting a cardiac transplant who has developed worsening hypotension. Option D is a 50-year-old woman with heart failure with preserved ejection fraction who also has symptomatic hypotension and worsening renal failure. Option E is a 67-year-old man with amyloid-induced cardiomyopathy who has Class IV symptoms, and he is not a candidate for cardiac transplant. 

[Dr. Handy] All right, we've touched on a few of the issues here. So an LVAS can be used for either long-term support or a bridge-to-transplant, and by definition, they support left ventricular function. Therefore, they're only used in patients with heart failure with reduced ejection fraction. So the patients with stress cardiomyopathy, amyloid, ischemic cardiomyopathy, and viral myocarditis may all be candidates. The patients for whom LVAS should ideally be employed include those with severe, persistent systolic heart failure symptoms who have failed to respond to optimal medical management. Commonly, these patients have marked functional limitation indicated by a peak oxygen consumption of less than 12 milliliters per kilogram per minute, or the patient is bound to continuous IV inotropic therapy owing to symptomatic hypotension or demonstrates worsening renal function or persistent refractory congestion. 

[Dr. Wiener] So the answer is D, right? The woman with heart failure with preserved ejection fraction, she's not a candidate. 

[Dr. Handy] Correct. That patient would not be considered a candidate. It sounds like she really needs more aggressive diuresis. And I should also mention that the role of LVAS in patients with less severe systolic dysfunction is still being investigated because the risk-to-benefit ratio is less clear in those patients. 

[Dr. Wiener] Okay, you brought up risk to benefit, so let's finish with talking about the complications of LVASs. 

[Dr. Handy] So just a few things to mention. First, since the LVAS relies on a gradient from the LV to the aorta, mean arterial blood pressure must be managed to be less than 90, using antihypertensives, if necessary. I've already mentioned the risk of stroke and hemolysis, which has improved with newer technology but is still a consideration. There's also a risk of LVAS thrombosis. To lessen this, most patients are on antiplatelet and anticoagulant medications, so bleeding, in particular, GI bleeding, is also a consideration. And since the LVAS is a foreign body, there's always a risk of infection, with some estimates up to 20% of cases. 

[Dr. Wiener] Great. So the teaching point in today's case is that left ventricular assist systems, or LVAS, are becoming more common as the prevalence of systolic heart failure increases and technology improves. These devices can be used as either a bridge-to-transplant or destination therapy, although studies to determine the long-term outcomes are ongoing. Patients with heart failure with preserved ejection fractions are not candidates for these devices. 

[Dr. Handy] This question and questions like it can be found on Harrison's self review or the review questions, and more information on LVAS can be found in the Harrison's chapter on cardiac transplantation and prolonged assisted circulation. Visit the show notes for links to helpful resources, including related chapters and review questions from Harrison's. And thank you so much for listening. If you enjoyed this episode, please leave us a review so we can reach more listeners just like you.

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