AI and cardiac med interactions

Yes, I had to go off of Letrozole and then Anastrozole when both of them kept raising my blood pressure. I initially had moderately high blood pressure but didn't have arrhythmia really, just occasional palpitations, and was on a Beta-blocker, then added in Amlodipine, (a Calcium channel blocker) and Olmesartan (an ARB) as my BP climbed. After 4 months on AI's my BP suddenly changed and became "labile", with me ending up in ER more than once, with BP's of 200/100. So I quite the AI's.....I am still stuck with the labile hypertension, and it is not fun, taking the super drug Hydralazine if it spikes high. I have read research that says people with cardiovascular disease shouldn't take AI's, but would have to look for that again. ~ Patty (Jardinera)

@jardinera25 I was told by my medical oncologist that AIs were my only option, as Tamoxifen would interfere with my heart issues and meds. I'm on Anastrozole (couldn't tolerate Letrozole) and my BP has a "new normal" (high) now.

Hi..... watching your BP climb may be a warning sign, as it was for me. As I said I had some hypertension before going on AI's, controlled by 2 meds. Once on AI's I watched my BP slowly climb, reported it to my cancer doc. She switched me to the other AI. My BP continued to climb (home monitoring) slower, but steadily. She should have told me to get off of it.
Then at around 3 months all heck broke loose and I started having severe BP spikes, to 200/100. My Doc was NOT doing careful cardiovascular monitoring, and I started seeing a Cardiologist, and learning all about labile hypertension. The episodes began getting worse over the next month and I said "I'm off this stuff!" Labile hypertension is horrible; you don't know when it will hit or how high. It doesn't go back to normal, you learn to control it as best you can with drugs.
Here are some studies linking AI's and Tamoxifen to adverse cardiac events due to "endothelial dysfunction." Your Doc may need to see one of these & respond. I don't believe they are safe for those with previous cardiovascular problems, including Hypertension.
I have subsequently tried a SERD (Fulvestrant) for 4 months and Tamoxifen, all of which gave me side effects that I don't trust. So am off all hormone blockers and feeling great. I have to decide what to try next (as a side note, I had breast cancer at 43 (30 years ago) and had a strong regimen of Chemotherapy drugs then, along with a mastectomy. I might just be too tired to keep trying drugs on this old body that impact my heart for breast cancer).
Good luck in the decision process, it's not easy.
https://www.fredhutch.org/en/news/releases/2022/04/major-study-links-breast-cancer-treatment-with-increased-risk-of.html
https://pmc.ncbi.nlm.nih.gov/articles/PMC10498727/ (very technical report)
https://ascopubs.org/doi/10.1200/JCO.2017.35.15_suppl.e12064

Thank you for sharing these research articles. I wish oncology teams would integrate cardiologists who specialize in cancer to make it easier for patients to monitor their heart health during and after cancer treatment. My cardiologist defers to my oncologist with his recommendations but I'm not always confident that as much as I trust my oncologist, she is able to stay abreast of all cardiac issues.

As someone who developed atrial fib shortly before my breast cancer diagnosis and who is taking Kisqali with its known cardiac issues, I probably would prefer someone who is on the aggressive side of monitoring. To me that would mean continuing to monitor with EKGS and Echos even beyond what Kisqali guidelines suggest. But that's just me. I would prefer to be on top of any cardiotoxic effects before they become acute.

@prarysky
How often do you have afib? I wish I hadn’t taken Kisqali. My afib started day 7 of Kisqali along with QT prolongation. The QTP stopped with a dose reduction to 400 but I had about 150 long afib episodes in the 5 years on Kisqali. I stopped Kisqali 8 months ago and afib frequency went from 1-2 times a week to once a month. It progressed in 5 years so now I’m left with needing cardiac ablations but have added risks. Wish I had switched to iBrance. My oncologist kept saying the afib was coincidence. I knew it wasn’t. I’m still on Letrozole. When I asked if he was sure it was safe to stop Kisqali he said, yes, Letrozole does all the heavy lifting. Then why did we destroy my heart rhythm with Kisqali?

Very important issue. Right from the get-go with the AIs I knew the possibility of cardiac side effects.
Anastrozole and Letrozole caused hypertension for me also despite already being on 3 different B/P medications.
2 had to be increase with only slight improvement. I was tolerating AI side effects but the labile B/P had me very worried plus I was getting truly awful headaches. If you read the drug info insert it clearly states caution in women with cardiovascular disease (which I have several issues) AIs can cause a heart attack or stroke. My cardiologist was aware of this...grudgingly gave his OK to take the AI's...clearly I was between a rock and hard place. Finally switched to exemestane and my B/P improved to normal ranges. Now my ono suggested Kisqali to add on. She herself said "you are on 5 medications with drug-drug interactions, you have to speak with your cardiologist". Apparently the main concern is heart medications, heart disease and QT prolongation with Kisqali. Within minutes of a phone call with the cardiology RN - I received a call back, my cardiologist who did not give his authorization to start Kisqali. My dilemma and my ono telling me "it's your decision to start Kisqali or not but it will give you another layer of protection" - was over, thank goodness, the decision was made for me. I was spending days "wondering" what to do. So a bullet was dodged for me.
This is my personal experience only. But if anyone has heart disease, under the care of their cardiologist - you should speak with him/her before starting this drug.
All the best to everyone!

@lak1967 Anastrozole completely prevented me from sleeping, no matter what sleep aids I tried. Exemestane caused a rash, so I’m currently on letrozole.

@paulsgerl Sorry to hear that. I hope the Letrozole works out for you!!🙏

@californiazebra I'm glad you no longer need the Kisqali and hope you'll avoid problems with the letrozole. My first afib episode was in August 2023 before my breast cancer diagnosis in the fall of 2024. Now I wonder if the afib was an indicator that I had cancer before the mammograms and other tests indicated it. The reason I say that is I had no risk factors for afib. My cardiologists (I saw a couple) asked if I had cancer since it was a risk factor for afib so perhaps the cancer triggered the afib. At the time when I saw these docs, I said no because I did not know I had cancer then. I had the impression it was the cancer itself, and not any medication treating it, that could be a cause. One of those mysteries of cause and effect we never answer.

My afib was episodic and I was prescribed Eliquis. I was on the fence about taking it but when I had a couple more afib episodes decided it was the safe thing to do. I also consulted with 2 electrophysiologists who both said I was a candidate for an ablation. I had planned to do the ablation in the fall of 2024 but when the breast cancer diagnosis was made late in 2024, the surgery was cancelled.

After completing a double mastectomy and chemotherapy in the spring of 2025, I asked my electrophysiologist if I was still a candidate for an ablation. He said yes. Although my cardiologist says I need to stay on the Eliquis regardless of an ablation (my age 76 and being female are risk factors), I elected to have the ablation. My electrophysiologist says I could go off the Eliquis with careful monitoring for afib. I feel the ablation is one potential thing to protect myself. Plus, research now indicators ablation should be considered a primary tool to treat afib rather than a backup if meds don't work.

I have had no afib episodes since my ablation in September 2025 but remain on the Eliquis too.

I'm happy that your afib episodes have decreased so much since dropping the Kisqali. I would encourage you to get at least 2 opinions about an ablation. It's also possible that your afib episodes will continue to decrease even more then longer you go without being on Kisqali. It's possible they may disappear completely! That is my sincere hope for you!

@prarysky
Thanks for your nice reply. I sure hope Letrozole is not contributing to my afib since I'll be on it forever as far as I know. I have recurrent breast cancer, came back 7 years after my DMX. I'm doing well though. I started Letrozole 2 weeks after I started Kisqali, but the afib started the first week of Kisqali. I had one afib episode 5 years before Kisqali after losing 25 pounds in a month due to dysphagia and not eating at all so I may be predisposed to afib, but Kisqali definitely fleshed it out. I did not know cancer was an afib risk factor. I looked it up and it's generally the inflammation is causes and the cancer treatments that are the issues. Medical issues definitely have a domino effect, one leads to another.

That's fantastic that your first ablation worked! Also glad you do well with Eliquis. I've had so many issues with meds, I refused to take Eliquis until I landed in the hospital last September from a TIA with aphasia. That was scary. I thought it was that major stroke they'd been warning me about. I had several retinal TIAs and one other cognitive one before Eliquis. I'm doing fine on Eliquis and no TIAs in the past 9 months while on it.

I'm 67. I have my 2nd opinion consult with a different EP next week. The first EP was a definite no. He was flippant. I'm less worried about the standard ablation risks and more worried about my personal risks due to anesthesia issues and a hereditary nerve disorder that makes my nerves easily damaged. I also have 2 venous anomalies that will change the catheter plan and two arterial anomalies I'm worried may increase stroke risk, all picked up incidentally on scans. I especially worry if I have to have multiple ablations.

I was also hoping my afib would be better and better over time now that I'm off Kisqali, but I've been off 8 months and continue to have about 1 episode a month (better than the 5 per month on Kisqali). I just finished a 65 hour episode today, my longest yet so I guess improvement without ablation isn't in the cards. My heart has obviously remodeled after 5 years of frequent and long episodes. I'm interested in PFA for less nerve risk and shorter anesthesia time. Did you have PFA? We'll see what the EP has to say. Hopefully, he's more optimistic than the last one. Thanks again for your response. I truly hope your ablation success is permanent.