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

Q: What is the clinical evidence from this study?

Study design: Case-Control. Population: Stage II–IV lung cancer (n=74). Intervention: Curative-intent thoracic radiotherapy vs. Sociodemographically matched healthy controls without radiotherapy. Primary outcome: Presence of fragmented QRS (fQRS) on 12-lead ECG (OR 4.44, 95% CI 1.10-17.9, p=0.027).

Q: What does this research mean for the field?

Fragmented QRS occurs with significantly higher prevalence in lung cancer patients following curative-intent thoracic radiotherapy compared with non-irradiated controls, serving as an early electrocardiographic marker of subclinical radiation-induced cardiotoxicity. Novelty: ClaimNovelty.INCREMENTAL. Consensus alignment: ConsensusAlignment.NEUTRAL.

Hasan Oğuz Kapıcıbaşı; Ercan Akşıt; Özgür Yildirim

doi:10.1186/s40959-026-00570-3

October 24, 2026Cardio-OncologyOpen Access

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

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Key result

Thoracic radiotherapy for lung cancer is linked to ~4.4-fold higher odds of fragmented QRS.

OR 4.44
95% CI 1.10-17.9
P=0.027
n=74

Why the study?

Cardiac exposure during thoracic radiotherapy may contribute to subclinical myocardial injury, but few studies have evaluated fragmented QRS in radiation-induced cardiotoxicity and data in lung cancer patients remain limited.

Does curative-intent thoracic radiotherapy increase the prevalence of fragmented QRS on electrocardiography in patients with locally advanced lung cancer compared with matched controls?

Key Points

To evaluate the incidence and determinants of fragmented QRS development as an early marker of radiation-induced cardiotoxicity in lung cancer patients receiving curative-intent radiotherapy.
Conducted a controlled observational study between September 2020 and September 2023 comparing 34 patients with locally advanced lung cancer treated with curative-intent thoracic radiotherapy (60–66 Gy) against 40 sociodemographically matched controls.
Obtained standard 12-lead electrocardiography during routine follow-up at a median of 4 months (range: 2–12 months) post-radiotherapy, defining fragmented QRS according to established criteria, alongside echocardiographic assessment.
Fragmented QRS was observed in 9 of 34 patients (26.5%) in the radiotherapy group versus 3 of 40 controls (7.5%), demonstrating a significantly higher prevalence with radiotherapy (OR: 4.44, 95% CI: 1.10–17.9, p = 0.027).
Echocardiographic parameters showed preserved systolic function with no significant difference between groups, including left ventricular ejection fraction (56.09 ± 6.73% vs. 56.85 ± 5.70%, p = 0.750).

Study Design

Type

Case-Control (n=74)

Blinding

Assessor-blinded

Multicenter

No

Structured PICO

Does curative-intent thoracic radiotherapy increase the prevalence of fragmented QRS on electrocardiography in patients with locally advanced lung cancer compared with matched controls?

P

Population

74 adults (mean age 63.3 years, 33.8% female), including 34 patients with stage II–IV lung cancer treated with curative-intent thoracic radiotherapy and 40 sociodemographically matched controls, evaluated at a median of 4 months post-radiotherapy.

E

Exposure

Curative-intent thoracic radiotherapy delivered via RapidArc volumetric modulated arc therapy (VMAT) with 6-MV photons once daily, 5 days per week, to a total prescribed dose of 60-66 Gy (2 Gy per fraction) over 6-6.5 weeks, with concurrent cisplatin-based chemotherapy (7 patients received curative postoperative radiotherapy).

C

Comparator

40 sociodemographically matched control subjects without lung cancer or radiotherapy, matched for baseline demographic and cardiovascular risk characteristics including sex, age, smoking status, and common comorbidities.

O

Outcome

Prevalence/incidence of fragmented QRS (fQRS) on standard 12-lead surface electrocardiography at a median of 4 months (range: 2-12 months) after completion of radiotherapy, evaluated by two independent blinded expert cardiologists.surrogate

Main Result

Odds Ratio: 4.44 (95% CI 1.1–17.9)

Absolute Event Rate: 26.5% vs 7.5%

p-value: p=0.027

Fragmented QRS on routine 12-lead ECG is significantly more prevalent in lung cancer patients following curative-intent thoracic radiotherapy despite preserved LVEF, suggesting it may serve as an early, low-cost marker of subclinical radiation-induced cardiotoxicity.

Limitations

Absence of baseline electrocardiographic evaluation prior to radiotherapy
Small sample size and limited number of fQRS events preventing multivariate regression analysis to adjust for confounders
Single-center retrospective design with lack of longitudinal follow-up and unknown long-term clinical outcomes
Inability to adequately adjust for concomitant chemotherapy or systematically exclude coronary artery disease via advanced imaging
Lack of patient-level cardiac dose-volume histogram (DVH) parameters for dose-response analysis
Absence of baseline electrocardiographic evaluation prior to radiotherapy to confirm whether fQRS was newly developed
Small sample size and limited number of fQRS events precluded multivariate regression analysis and adjustment for confounders
Retrospective, single-center case-control design with lack of longitudinal follow-up and unknown long-term clinical outcomes
Unavailable patient-level cardiac dose-volume histogram (DVH) parameters for dose-response analysis
Potential confounders such as concomitant chemotherapy and unexcluded coronary artery disease could not be systematically addressed

Implication

fQRS prevalence was higher after radiotherapy; hypothesis-generating for early cardiotoxicity marker, needs prospective validation.

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.

Discussion

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Cite This Study

Kapıcıbaşı et al. (2026) conducted a case-control in Stage II–IV lung cancer (n=74). Curative-intent thoracic radiotherapy vs. Sociodemographically matched healthy controls without radiotherapy was evaluated on Presence of fragmented QRS (fQRS) on 12-lead ECG (OR 4.44, 95% CI 1.10-17.9, p=0.027). Curative-intent thoracic radiotherapy in lung cancer patients was associated with a higher prevalence of fragmented QRS compared to controls (26.5% vs 7.5%; OR 4.44, 95% CI 1.10–17.9, p=0.027).

synapsesocial.com/papers/6adde7e6df72b09fd59bee8b https://doi.org/10.1186/s40959-026-00570-3

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

Key Points

Study Design

Structured PICO

Main Result

Limitations

Implication

Abstract

Discussion

Cite This Study

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

Key Points

Study Design

Structured PICO

Main Result

Limitations

Implication

Abstract

Discussion

Cite This Study

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