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Dr. Swift:
This is Continuing Education with the Global Learning Collaborative, and I'm Dr. Pauline Swift, and here with me today is Dr. Nihar Desai.

Dr. Desai:
Hi, Pauline.

Dr. Swift:
Hi, Nihar. When you're using a potassium binder to prevent hyperkalemia, what are the specific concerns related to heart failure that our listeners should keep in mind?

Dr. Desai:
I think it's really important to just reemphasize the primary role of modern potassium binders as we think about maintaining and maybe even initiating or intensifying background RAASi therapy, in particular for patients with heart failure and/or other important contextual comorbidities.

And so we've got 2 modern potassium binders, patiromer and sodium zirconium cyclosilicate, or SZC. And I think there is an important kind of difference in the mechanism of action across the 2 binders.

So patiromer is primarily a calcium-based exchange. In contrast, SZC is a sodium or hydrogen-based exchange for the potassium. In fact, about every 5 g of SZC has about 400 mg of sodium, and so a natural sort of question arises: Hey, as I'm seeing patients in my clinical practice that have developed hyperkalemia, that have hyperkalemia, and if I am going to select a potassium binder to manage that hyperkalemia in order to maintain and facilitate the use of important background RAAS-blocking therapies, how might I choose between patiromer and SZC? And specifically, does the difference in the mechanism, and does the difference in sort of sodium-based exchange, have any important clinical implications?

And I will say, there have been some signals in prior clinical trials that were placebo controlled of SZC, and those would be from the PRIORITIZE program, from the HARMONIZE program, and then even more recently in the REALIZE-K clinical trial, showing that there might be a signal for an increase in edema-related events and in heart failure hospitalizations with that particular binder.

Now again, I think we have to sort of take that into context, using a binder, I think, is preferred to down-titrating or discontinuing RAASi therapy.

And now we're sort of getting in a discussion around selecting across the 2 different modern binders, and there again there is a difference in the mechanism, and there might be an important clinical effect, given that SZC has that sodium load associated with it. For patients that are volume sensitive, are heart failure patients, those patients that seem to be exquisitely volume sensitive or salt sensitive, that sodium load might be associated with some increase in edema-related events, fluid-related events.

Dr. Swift:
And I think perhaps the key message here is that potassium binders shouldn't necessarily be regarded as interchangeable, particularly in patients, as you're saying, with heart failure and a tendency towards fluid retention. So we need to look at the whole clinical picture here, don't we? Not simply just what is the potassium concentration on the lab results? We need to, of course, ask why is the potassium gone up now? Has the diuretic dose been reduced? And has there been a change in diet or a loss of kidney function?

But in somebody with heart failure with reduced ejection fraction, who has persistent congestion, recurrent edema, high loop diuretic requirements, or a recent admission with volume overload, I would think carefully about sodium exchanges you've talked us through associated with sodium zirconium and cyclosilicate. So SZC can be very effective. It has the advantage of being a rapid potassium reduction. But the nuance is in that patients who are particularly sodium sensitive, as you've said, are struggling with volume control, I think I may favor a patiromer type of binder because it exchanges potassium for calcium, as you've said, rather than introducing sodium exchange. So really, I would say that the key takeaway here for us should be don't just ask how high the potassium is; ask about the clinical phenotype and the characteristics of the patient.

Dr. Desai:
Yeah, thanks, Pauline. That was very well said, and I couldn't agree more.

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