Reduction of Major Adverse Cardiac Events (MACE) with Low Left Coronary Artery Dose Exposure Query Current Guidelines for Reducing Cardiac Toxicity

Presenting author:
Katelyn Mae Atkins MD, PhD

by Eulanca Y. Liu, PhD, University of California San Diego School of Medicine 

Major adverse cardiac events (MACE) and mortality are rare but very significant sequelae of thoracic radiotherapy for lung and breast malignancies and, thus, have prompted identification of mean threshold doses to the heart. In their recent work, Isolated Low Left Coronary Artery Dose Exposure Reduces the Risk of Major Adverse Cardiac Events in Lung Cancer Radiotherapy: Should Mean Heart Dose Be Retired?, Katelyn Atkins, MD, PhD, and colleagues identified dose parameters to the left anterior descending and left circumflex arteries as most predictive of MACE compared to whole heart or other substructures in 701 patients treated for locally advanced non-small cell lung cancers (NSCLC).

This retrospective analysis separated the cohort into four dosimetric groups based on high or low mean heart dose and coronary artery dose. Cumulative incidence of MACE, including unstable angina, heart failure, myocardial infarction, coronary revascularization and cardiac death, was estimated with regressions adjusted for pre-existing CHD, age and intensity modulated radiation therapy (IMRT) use. Critically, mean heart and left coronary dose exposure were found to be discordant in 15.1% of cases. They found that only combinations of dosing with low left coronary artery dose were associated with significantly reduced risk of MACE. Given the increasing nuance of coronary dosimetry, and “as more robust cardiac sub-structure dosimetric predictors of cardiac toxicity are validated, national guidelines for mean heart dose and whole heart metrics should be re-evaluated,” stated Dr. Atkins.

Given the limitations of mean heart dose and emerging data supporting optimal dose constraints to these specific cardiac substructures, the authors are most interested in next investigating radiation planning decision support methods to optimize a personalized risk balance between cardiac and pulmonary toxicity and tumor control and testing this in the clinic.

Dr. Atkins has long held interest in molecular radiation response pathways since her graduate school years, during which her research training funneled into a passion to better understand radiation toxicities in an effort to personalize strategies for risk mitigation. She reflects, “It struck me early in residency how little we understood as a field about cardiac dosimetry and what a wide impact this could have across disease sites by taking a more elegant and nuanced approach to cardiac risk stratification and risk mitigation strategies.”

Isolated Low Left Coronary Artery Dose Exposure Reduces the Risk of Major Adverse Cardiac Events in Lung Cancer Radiotherapy: Should Mean Heart Dose Be Retired? was presented on Sunday, October 25 in the Science Center, as part of Quick Pitch (QP) 08.

Published on: October 26, 2020