REN and muscle atrophy: Notably, patients with LVEF <50% may further amplify the risk effects of the TyG/HDL-C ratio through dual pathological pathways: on one hand, skeletal muscle atrophy and mitochondrial oxidative phosphorylation dysfunction lead to peripheral IR deterioration, driving abnormal elevation of the TyG index (79–81); on the other hand, systemic inflammatory states and overactivation of the renin-angiotensin system contribute to depletion in both HDL-C levels and its anti-inflammatory function (82–84).