Fragmented QRS as an early marker of radiation-induced cardiotoxicity in lung cancer patients: a controlled observational study

Abstract Background Fragmented QRS (fQRS) is an electrocardiographic marker reflecting myocardial scarring and conduction heterogeneity and has been linked to adverse cardiac outcomes. Cardiac exposure during thoracic radiotherapy (RT) may contribute to subclinical myocardial injury. Objectives To assess the incidence and determinants of fragmented QRS development in lung cancer patients undergoing curative-intent radiotherapy. To our knowledge, few studies have evaluated fragmented QRS in the setting of radiation-induced cardiotoxicity, and data specifically focusing on lung cancer patients receiving thoracic radiotherapy remain limited. Methods Between September 2020 and September 2023, 34 lung cancer patients treated with curative-intent radiotherapy were compared with 40 sociodemographically matched controls. Patients were aged ≥ 18 years and had local advanced lung cancer. Individuals with cardiac implantable electronic devices, acute coronary syndrome, systemic connective tissue disease, sarcoidosis, or inadequate electrocardiographic data were excluded. All patients in the radiotherapy group underwent standard 12-lead electrocardiography after completion of curative-intent thoracic radiotherapy. ECG recordings were obtained during routine follow-up visits at a median of 4 months (range: 2–12 months) after completion of radiotherapy.Fragmented QRS was identified according to established criteria. Results Fragmented QRS was observed in 9 of 34 patients (26.5%) in the radiotherapy group and in 3 of 40 controls (7.5%). The prevalence of fQRS was significantly higher among patients who received radiotherapy ( p = 0.027). Conclusions Fragmented QRS appears to occur with increased frequency in lung cancer patients treated with curative-intent radiotherapy and may represent an early electrocardiographic marker of radiation-induced cardiotoxicity. Careful attention to cardiac dose during treatment planning, routine ECG surveillance, and additional cardiac evaluation should be considered in patients with detected fQRS.