Patients with NSCLC receive radiotherapy. The radiation exposure can adversely affect the heart structures. It can lead to coronary heart disease (CHD) and death. But the clinicians do not have stringent planning parameters for radiotherapy. This study examines dosage thresholds and cardiac substructures for MACE – major adverse cardiac events.

The retrospective analysis involves 701 patients with locally advanced NSCLC. They received thoracic radiotherapy for over 11 years. The cohort study analyzed data and manually delineated the cardiac substructures. Specific Gray(Gy) dose parameters in 5-Gy increments were calculated. Researchers used techniques like Fine, Gray, and Cox regression and cut point analyses. The study also included MACE estimates, prognostic, and preexisting CHD adjustments.

For substructure and radiotherapy doses, optimal cut-points were obtained. They include V15 Gy, left circumflex coronary artery >= 14%, and mean coronary artery dose >= 7 Gy. The risks associated with and without CHD were also noted among the patients after adjustments.

Preexisting CHD imposes dose constraints, increase MACE risk with left ventricle Gy >= 1%. Patients without CHD are also at risk as left anterior descending V15 Gy>=10% appears to indicate all-cause mortality and MACE independently. Further studies, risk stratification, and mitigation strategies are necessary.