Cardio-Oncology (Jan 2022)

Influence of extracellular volume fraction on peak exercise oxygen pulse following thoracic radiotherapy

  • Justin M. Canada,
  • Elisabeth Weiss,
  • John D. Grizzard,
  • Cory R. Trankle,
  • Leila Rezai Gharai,
  • Franklin Dana,
  • Leo F. Buckley,
  • Salvatore Carbone,
  • Dinesh Kadariya,
  • Anthony Ricco,
  • Jennifer H. Jordan,
  • Ronald K. Evans,
  • Ryan S. Garten,
  • Benjamin W. Van Tassell,
  • W. Gregory Hundley,
  • Antonio Abbate

DOI
https://doi.org/10.1186/s40959-021-00127-6
Journal volume & issue
Vol. 8, no. 1
pp. 1 – 11

Abstract

Read online

Abstract Background Radiation-induced myocardial fibrosis increases heart failure (HF) risk and is associated with a restrictive cardiomyopathy phenotype. The myocardial extracellular volume fraction (ECVF) using contrast-enhanced cardiac magnetic resonance (CMR) quantifies the extent of fibrosis which, in severe cases, results in a noncompliant left ventricle (LV) with an inability to augment exercise stroke volume (SV). The peak exercise oxygen pulse (O2Pulse), a noninvasive surrogate for exercise SV, may provide mechanistic insight into cardiac reserve. The relationship between LV ECVF and O2Pulse following thoracic radiotherapy has not been explored. Methods Patients who underwent thoracic radiotherapy for chest malignancies with significant incidental heart dose (≥5 Gray (Gy), ≥10% heart) without a pre-cancer treatment history of HF underwent cardiopulmonary exercise testing to determine O2Pulse, contrast-enhanced CMR, and N-terminal pro-brain natriuretic peptide (NTproBNP) measurement. Multivariable-analyses were performed to identify factors associated with O2Pulse normalized for age/gender/anthropometrics. Results Thirty patients (median [IQR] age 63 [57–67] years, 18 [60%] female, 2.0 [0.6–3.8] years post-radiotherapy) were included. The peak VO2 was 1376 [1057–1552] mL·min− 1, peak HR = 150 [122–164] bpm, resulting in an O2Pulse of 9.2 [7.5–10.7] mL/beat or 82 (66–96) % of predicted. The ECVF, LV ejection fraction, heart volume receiving ≥10 Gy, and NTproBNP were independently associated with %O2Pulse (P < .001). Conclusions In patients with prior radiotherapy heart exposure, %-predicted O2Pulse is inversely associated markers of diffuse fibrosis (ECVF), ventricular wall stress (NTproBNP), radiotherapy heart dose, and positively related to LV function. Increased LV ECVF may reflect a potential etiology of impaired LV SV reserve in patients receiving thoracic radiotherapy for chest malignancies.

Keywords