Cardiac rhythm disorders as cardiovascular toxicity of immune checkpoint inhibitors therapy: incidence and prognostic value

Introduction While immune checkpoint inhibitors (ICI) have fundamentally improved cancer outcomes, cardiovascular toxicity has emerged as a critical limitation of therapy. Cardiac rhythm disorders represent an important yet understudied manifestation of ICI-related cardiovascular toxicity, with limited data on their clinical spectrum and prognostic relevance. Purpose This research aims to assess the burden and types of arrhythmias in ICI therapy in a large patient cohort and to examine the relationship between these clinical findings and survival. Methods Patients treated with ICI from a local registry (EcoR) were systematically screened for cardiac rhythm disorders in accordance with European Society of Cardiology Cardio-Oncology guideline definitions. Patients underwent structured cardio-oncology assessments at baseline and at 6 weeks, 3 months, 6 months, 1 year, and 2 years of follow-up. Arrhythmias were categorized as bradyarrhythmias, atrial fibrillation (AF), supraventricular arrhythmias (atrial tachycardias or supraventricular extrasystoles (SVES)), ventricular tachycardias, ventricular extrasystoles (VES), and QT prolongation (>480 ms). Results A total of 568 patients out of 2,840 in the registry were screened for arrhythmias. The median age was 63 years (Q1:53, Q3:74), and males represented the 58.8% (334/568). Dermatological malignancies were the most common cancer type (86.8%, 493/568). Arrhythmias were observed in 29.8% (169/568) of participants, whereas baseline arrhythmias occurred in 15.8% (90/568). AF was detected in 7.9% (45/568) of participants. Other supraventricular arrhythmias were documented in 11.3% (64/568) of patients (50 with atrial tachycardias and 14 with SVES). Sinus bradycardia was present in 6.9% (39/568) of patients. Only 15 patients had VES, while no ventricular tachycardias were documented. 2-year survival in patients without arrhythmias, with baseline arrhythmias, and with new-onset arrhythmia was similar. Conclusion Arrhythmias are frequent during ICI therapy but are not associated with reduced survival, indicating a generally favorable prognostic profile under systematic cardio-oncology surveillance.