Dr Fradley on Real-World Atrial Fibrillation and Cardiovascular Outcomes in CLL

If a [patient] developed atrial fibrillation within 1 year of their CLL diagnosis, we saw that they had significantly worse cardiovascular outcomes.

Michael G. Fradley, MD, a professor of clinical medicine (cardiovascular medicine), section chief of Consultative Cardiology, and medical director of the Thalheimer Center for Cardio-Oncology at Penn Medicine, discussed real-world data presented on the incidence of atrial fibrillation (AFib) in patients with chronic lymphocytic leukemia (CLL) or small lymphocytic lymphoma (SLL), and its effect on cardiovascular outcomes and health care resource utilization.

In a retrospective study, data from which were presented at the 2026 ASCO Annual Meeting, Fradley and colleagues used the US Symphony Health open claims database, which captures both privately insured and Medicare populations, Fradley explained. Among 233,362 patients with newly diagnosed CLL/SLL, 13.1% developed AFib within 1 year of diagnosis. Baseline characteristics did not differ significantly between patients who did and did not develop AFib, he noted.

However, patients who developed AFib (n = 30,518) had higher rates of stroke (14.3% vs 8.9%), bleeding events (27.9% vs 19.1%), and heart failure (54.5% vs 18.9%) than those who did not (n = 202,844; all, P < .0001).

In an exploratory analysis of 22,636 patients who started frontline treatment with a BTK inhibitor, Fradley noted that prior data suggest that AFib rates are highest with the first-generation agent ibrutinib (Imbruvica) and lower with acalabrutinib (Calquence) and zanubrutinib (Brukinsa). In this cohort, AFib occurred in 16.0% of patients treated with ibrutinib (n = 15,325), 13.0% of those treated with acalabrutinib (n = 5447), and 11.0% of those treated with zanubrutinib (n = 1864; P < .0001). The analysis is not definitive but is hypothesis generating, he added.

The lower AFib rate with zanubrutinib also translated to fewer cardiovascular adverse effects among patients who developed AFib, according to Fradley. Among patients with AFib, 4.8% of those treated with zanubrutinib had a stroke vs 12.2% of those treated with ibrutinib.

Fradley also highlighted the resource utilization findings, noting that AFib places a significant financial burden on the health care system. Patients with CLL who developed AFib had significantly greater outpatient, inpatient, and other medical service use than those who did not (P < .0001).