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RIBOCICLIB AND CARDIAC OUTCOMES IN BREAST CANCER PATIENT
Conference poster   Peer reviewed

RIBOCICLIB AND CARDIAC OUTCOMES IN BREAST CANCER PATIENT

Gokul Karthikeyan, Feras Al Moussally, Mohammed Rahhal and Anas Atrash
Journal of the American College of Cardiology, v 87(13), pp A1086-A1087
07 Apr 2026
DOI: https://doi.org/10.1016/j.jacc.2026.02.2665
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https://doi.org/10.1016/j.jacc.2026.02.2665View
Published, Version of Record (VoR) Restricted Open Access (License Unspecified)

Abstract

Background Ribociclib, a CDK4/6 inhibitor for HR+/HER2- breast cancer, carries a known risk of QTc prolongation. In pooled MONALEESA-2, -3, and -7 trials, QTcF >480 ms occurred in 5.2%, >500 ms in 1.4%, increases ≥60 ms in 5.8%, and serious arrhythmias were rare. In the adjuvant NATALEE trial, all-grade QTc prolongation occurred in 4.3% and grade ≥3 events in 0.3%, with no reported torsades de pointes. These data support routine ECG monitoring during ribociclib treatment to ensure cardiac safety. Methods Using the TriNetX Global Collaborative Network (154 healthcare organizations), we defined a cohort of 4,775 patients with breast cancer who initiated ribociclib and had no prior diagnosis of arrhythmia. The index date was the day of first ribociclib initiation following breast cancer; outcomes were assessed from one day post-index onward, with no maximum follow-up. Outcomes included atrial fibrillation/flutter, other cardiac arrhythmias, long QT syndrome, and cardiac arrest. Analyses included risk estimates, Kaplan-Meier survival curves, and instance count distributions. Results Among 4,775 patients with breast cancer treated with ribociclib and no prior arrhythmia, atrial fibrillation/flutter occurred in 1.4% (n=67), survival ∼95.96%. Other cardiac arrhythmias were observed in 11.3% (n=541), survival ∼71.4%. Long QT syndrome was rare at 0.4% (n=19), survival ∼99.41%. Cardiac arrest occurred in 0.4% (n=20), survival ∼98.37%. Conclusion Our study of 4,775 breast cancer patients with no prior arrhythmia who started ribociclib showed a low incidence of long QT syndrome (0.4%) and cardiac arrest (0.4%), with nearly 99% and 98% survival probabilities, respectively. Atrial fibrillation/flutter occurred in 1.4% of patients, and broader cardiac arrhythmias were more frequent at 11.3%, with a corresponding survival probability of 71.4%. Compared to clinical trials and prior real-world data, which reported QTc prolongation incidences between 0.1% and 5.2%, with rare serious arrhythmias and no torsades de pointes, our findings confirm ribociclib’s measurable but low cardiac risk, supporting the importance of routine cardiac monitoring to maintain safety during treatment.

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