Various Medications Can Cause QTc Prolongation in Geriatric Populations, Not All Prescribers Are Aware of the Risk
ASCP 2022 session presenters discuss medications that can cause QTc prolongation, with a particular emphasis on a review of the literature with regards to QTc prolongation and antipsychotics.
Pharmacy Times® interviewed Lindsay K. Benedik, PharmD, BCPS, BCGP, assistant professor, medical education and geriatrics at Wright State University, and Marty Eng, PharmD, BCGP, BCPP, professor of pharmacy practice at Cedarville University, discusses their presentation at the American Society of Consultant Pharmacists (ASCP) 2022 Annual Meeting titled QTc Prolongation and Antipsychotics: A Pharmacist’s Guide to Monitoring and Intervention. The session provides an overview of the value of using the electrocardiogram (EKG) to help monitor medications, especially medications that could cause QTc prolongation. Additionally, Benedik and Eng discuss the importance of understanding QTc and the various medications that can cause QTc prolongation.
The ASCP 2022 Annual Meeting will be held at the JW Marriott San Antonio Hill Country Resort & Spa in San Antonio, Texas.
Pharmacy Times®: What is the value of the EKG when working with senior patients, and what information can it provide?
Lindsay K. Benedik: Well, an EKG can be a valuable tool in the management of any patient. But speaking specifically of senior patients, an EKG can provide a lot of information about the overall health of a patient's heart rate. So how well it's conducting electrical signals, and what the patient's risk would be for dysrhythmias, or are there signs of structural abnormalities that we would have to be worried about. Overall, [an EKG] can just give us a good guidance as to any potential disruptions in how the cardiac conduction system is working.
Pharmacy Times®: What are some best practices in the day-to-day use of an EKG by a senior care pharmacist working with this long-term care population?
Lindsay K. Benedik: There really are no great best practices, and I think that's part of the reason we wanted to put this presentation together because we don't necessarily have just like a good guidance.
That being said, there are a lot of opportunities to use an EKG to help monitor medications and specifically medications that would prolong the QT interval, evaluating patients, whereas for those types of things, as I mentioned, it can be a very useful tool to see what's going on. But it's one of those things that you have to pick the patients appropriately because EKG’s do cost money, and they may not be readily available in facilities. So we have to select our patients properly with regard to those that would benefit from EKG monitoring versus patients that maybe we can get away without monitoring the EKG and just monitoring other parameters to ensure the patient's overall safety.
Pharmacy Times®: What is the importance of the QTc, and what are some warning signs senior care pharmacists should pay attention to or make note of?
Lindsay K. Benedik: So the QTc is basically a surrogate marker for monitoring the refractory period of the ventricles, which basically is the time period in which the electrical conduction system is resetting. If you prolong that QTc, and an electrical signal were to fire and hit those cells and that portion of the heart, you can actually get a fatal dysrhythmia. So basically, you're triggering before it's quite ready, and so you have these erratic signals. And the biggest complication would be Torsades de Pointes, which is a potentially fatal dysrhythmia.
So having a prolonged QTc is basically proportional to your risk of developing Torsades. So as your QTc prolongs, that risk goes up. That being said, usually we don't start worrying until they're over what the normal limits would be. And the upper limit of where you really should start having a lot of concerns if the QTc is greater than 500.
There are lots of medications and different things that can impact the QTc, which we're going to kind of talk about, but those factors, from a pharmacist perspective, just understanding what medications cause QTc prolongation, and which ones are the most likely to trigger a fatal dysrhythmia is probably the number one thing to kind of keep in the back of your mind when you're managing older adults, particularly older adults with cardiovascular disease.
Pharmacy Times®: What is the impact of antipsychotics on QTc prolongation?
Marty Eng: I think there's a lot of consistency in the literature to show that many of the antipsychotics prolong QTc. Some of the different variables are the doses for sure. The higher the dose, the more likely they are to prolong QTc. The specific generations of antipsychotics have also been associated with different prolongation times. Definitely the route is a factor that impacts that as well.
Pharmacy Times®: What are some other medications that cause QTc prolongation that senior care pharmacists should take note of?
Marty Eng: One of the things that came out of the research for doing some of this is that there's over 200 different medications that have been associated with prolonging QTc. That's quite a bit. The classes range from antibiotics to antiarrhythmics and other antidepressants, and then antiemetics as well. So there's quite a range of different medication classes that could contribute to this.
Pharmacy Times®: What are some valuable monitoring parameters to consider regarding QTc prolongation?
Marty Eng: This is a really important because I think even more so than knowing some of these drugs that can prolong it QTc is paying attention to other factors that increase the risk for QTc that might not be on the radar screen such as bradycardia, structural heart disease, people that have had maybe previous heart attacks, electrolyte abnormalities, in particular, are something that I think are very, very crucial to pay attention to as well in this scenario.
It's really interesting because we talked about tools earlier. We have anticholinergic burden scales, but we don't really have a QTc burden scale. So when you start combining all of these potentially smaller prolongations, the question becomes—does that increase the risk of burden on QTc. I think that's what some of these other factors and tools and monitoring like the EKG can potentially give us—that kind of information for an individual.
Lindsay K. Benedik: I would just also add to that, too, is the cardiac conduction system is very delicate and very sensitive to outside forces. So electrolyte management—I always like to use the example of your charger cord, and that phrase at the end, so that would be indicative, like a structural abnormality, that cord isn't going to move electricity, so it's not going to charge your phone or your computer as well as it did before it was damaged. So now, when you have a patient with structural heart disease, which is more likely, in an older adult, particularly someone who's had a heart attack, or other conditions that may have caused abnormalities, that'll change how the heart conducts electricity, but also electrolytes, and the movement of electrolytes through those membranes can kind of trigger that action potential. So that's a huge component to managing all of these things.
Then you add medications that interfere with all of these pathways and induction systems and electrolyte channels—that'll just compound to that. As Marty has already said, we kind of don't really know how—we don't have a whole ton of great tools to say, ‘Here's how these factors all meet. And this is really what the patient's risk is,’ versus another patient that has all these other risk factors, we can just we have a couple of comparisons.
Pharmacy Times®: Any closing thoughts?
Lindsay K. Benedik: So I feel like QTc prolongation is something that we've always talked about in pharmacy school, you talk about it in residency and things like that, but it's not something—so we know the risk associated—but it's not always something that we, as clinicians—it took me a while as a clinician to really understand the impact that it has on my patients and their risk for having other complications, but also just the impact I as a pharmacist can have in educating providers and saying, ‘Hey, this medication can potentially cause this complication, they also have all of these other risk factors.’ So we think it's really important for pharmacists to help be that advocate for our patients, making sure and encouraging this is just one more opportunity to be advocates for our patients but also encouraging pharmacists to take another step in providing education to providers and patients about overall medication safety.
Marty Eng: Yeah, and I would say from a geriatric standpoint, it's been very interesting myself to look through the material. It can refresh and try to engage some of the tools and some of my attitudes that have been there that we see in our prescribing colleagues as well are things that we hope that the tools and the information you gain from the session will better equip you to engage those. We certainly want to balance doing good for the patients and not doing any harm.
A lot of times with the acute situations that come up to us, these antipsychotics sometimes overshadows the potential harms that are present and that sometimes even accumulate over time, which is a real significant geriatric scenario. So we're hoping that I think you'll gain a lot of tools and insight from some of the experiences and to learn from other people's experiences as well as they engage in this session with us.