Kisqali and Letrozole have heart issues?

Yes. I’ve been taking Kisqali and Letrozole for 3.5 years. My issues started on day 5 of taking the meds when I could feel my heart flipping out. I believe Kisqali is the culprit. Day 5 is when I started having issues with afib. The EKG also showed I was having the uncommon side effect (4% of people) QT prolongation which is a dangerous heart rhythm that can cause sudden heart failure. When we lowered my dose from 600 mg to 400 mg that stopped but I have continued to have afib issues. I have a very healthy heart other than that.

Sorry to hear about your heart attack! How long had you been taking the medications?

Oh, and I just remembered that I started Letrozole 2 weeks after I started Kisqali because I wanted to be able to tell which med was causing which side effect so the heart issues started with the Kisqali before I started letrozole. Arrhythmias and QT prolongation are both listed as possible side effects to Kisqali even though my oncologist tells me the afib is just a coincidence. Sure. Coincidence is his favorite word.

Thanks for the info! I started the Letrozole in November (2023) and as far as I could tell was having no issues. Started the Kisqali the beginning of February 2024 (2 months later) This heart attack/issue happened on August 12th so about 6 months later. I am leaning toward the Kisqali too. I have an appointment soon with Oncology/Cardiac and hoping to get straightened out - the medications were working so well for the cancer. . .Hope you are doing well!

Did you stop the meds? So scary for you. The lower dose of Kisqali is effective for me. There are two similar meds, Ibrance and Verzenio if you can’t continue Kisqali. They don’t seem to have the same cardiac effect, but verzenio causes severe diarrhea for a lot of people. No thanks. I was told Kisqali has the best clinical trial results for extending life span so I’ve stuck with it, but a heart attack would make me think twice if they don’t find another cause. I hope you get the answers and treatment you need. Blessings!

My dosage was reduced from 600 to 400. I have been told I will probably start back on Ibrance along with the Letrozole. I will see what the “verdict” is next week when I meet with my team. 🙏. Keep in touch and let me know how you are doing as you continue your journey.

Okay. Please let me know what they determine. ❤️

Will do!

I am on letrozole only. My heart is doing well. I love how you both do not live with it. You get to the Doctors office and let them know.

Lots of women have trouble with Letrozole from the get-go. Within 24 hours of starting Letrozole, I had horrible side effects. The nurse said it was "too soon" for me to be having severe adverse reactions to that med. Fortunately for me, several women on Mayo Connect had posted their concerns about Letrozole and not being taken seriously about concomitant early adverse reactions. My peripheral neuropathy immediately came back with a vengeance, much worse than it had been before. So when I got back to my chemo oncologist's nurse-gatekeeper, I relayed that women's early concerns about Letrozole were often ignored because of a baseless surmise that it was "too soon." I really had to press to get a satisfactory result. I said, okay, assuming arguendo that it wasn't the Letrozole, I still had a big problem that required diagnosis and treatment. Suddenly, lights went on and Occam's Razor seemed like the correct principle to apply. They switched my estrogen suppressors from Letrozole to Exemestane, and I have not had any side effects since.

Thanks! Something to look in to! Hope you are feeling better and I appreciate you sharing your experience!