INTRODUCTION We evaluated the incidence of cardiac events after chemoradiotherapy in patients with stage III non-small cell lung cancer (NSCLC) based on baseline cardiovascular risk and the heart substructures' radiation dose.

METHODS From 2008 to 2018, the cardiac events of 258 patients with stage III NSCLC who received definitive chemoradiotherapy were reviewed. The 10-year cardiovascular risk was calculated using the Atherosclerotic Cardiovascular Disease (ASCVD) scoring system. Dose-volume histograms were estimated for each cardiac chamber. A multivariate competing-risk regression analysis was conducted to assess each cardiac event's subhazard function (SHR).

RESULTS The median follow-up was 27.5 months overall and 38.9 months for survivors. Among the 179 deaths, none was definitely related to cardiac conditions. Altogether, 32 cardiovascular events affected 27 patients (10.5%) after chemoradiotherapy. Ten were major cardiac adverse events, including heart failure (N = 6) and acute coronary syndrome (ACS, N = 4). Most cardiovascular events were related to well-known risk factors. However, the volume percentage of the left ventricle (LV) receiving 60 Gy (LV V60) > 0 was significantly associated with ACS (SHR = 9.49, 95% CI = 1.28-70.53, P = 0.028). In patients with high cardiovascular risk (ASCVD score > 7.5%), LV V60 > 0% remained a negative ACS prognostic factor (P = 0.003). Meanwhile, in patients with low cardiovascular risk, the LV radiation dose was not associated with ACS events (P = 0.242).

CONCLUSIONS A high LV radiation dose could increase ACS events in patients with stage III NSCLC and high cardiovascular risk. Pre-treatment cardiac risk evaluation and individualized surveillance may help prevent cardiac events after chemoradiotherapy.