CHyLL bro.

Top Line: How can we identify patients at risk of major cardiac events after radiation for NSCLC?

The Study: We’ve learned that the left anterior descending coronary artery (LAD) V15Gy is independently associated with increased risk of major adverse cardiac events (MACE) in patients receiving definitive radiation for NSCLC. V15 > 10% is a good threshold for increased risk of MACE. We’ve also learned that mean heart dose (MHD) is a poor surrogate for LAD V15, and even with a low MHD, a high LAD V15 increases MACE risk. The authors who brought us those findings are back with a MACE risk prediction model that incorporates patient cardiac risk factors and cardiac dosimetry. Patients (n=701) used in the study had stage II-III NSCLC and received radiation therapy at 1.8-2Gy per fraction. Heart dose objectives were pretty standard. MACEs occurred in 9.2% of patients, and 57% of MACEs were ischemic events. The final model incorporated coronary heart disease (CHD), hypertension, and LAD V15 as the strongest predictors of MACE after RT. In addition, a factor accounting for the interaction between CHD and LAD V15 was included. CHD included coronary artery disease, congestive heart failure, extensive coronary artery calcifications, peripheral vascular disease, or stroke. The following formula was used to calculate the CHyLL risk score: CHyLL = 5.51*CHD + 1.28*HTN + 1.48*ln(LADV15 + 1) - 1.36CHD^ln(LADV15 + 1). A score of 5 was used to identify low risk (CHyLL<5) and high risk (CHyLL≥5). Most patients (>50%) were categorized as high risk. The rate of MACE was 0% v 17.7% at 36 months and 0% v 21.5% at 48 months for low v high risk patients.Those with the highest CHyLL scores (≥7) had a MACE risk of >30% at 48 months. There was also a trend towards association between CHyLL and overall survival. The only modifiable factor in CHyLL is LADV15. To be low risk, the V15 could be as high as 28.3% in patients with neither HTN nor CHD and as high as 11.3% in patients with HTN but no CHD. Those with CHD are high risk, so V15 should be as low as is achievable.

TBL: The CHyLL score is a useful tool to estimate the risk of MACE after RT for NSCLC. Those at high risk could benefit from further optimization of the LAD15 and primary and secondary cardiac prevention strategies. | Tjong, Radiother Oncol 2022