NPPB and hydrops fetalis: In this cross-sectional analysis of patients with significant incidental heart exposure following thoracic radiotherapy without an established history of CVD or HF, we found peak exercise %O2Pulse (a normalized surrogate of exercise LV SV response) was inversely associated with a CMR-derived marker of diffuse myocardial fibrosis (LV ECVF), ventricular wall stress (NTproBNP), cardiac radiation dose, and positively related to cardiac function (LVEF).