Anthracycline cardiotoxicity: role of metabolic vulnerability induced by cardiac pressure overload

BACKGROUND AND AIMS: Hypertension and valvular heart disease, both associated with left ventricular (LV) pressure overload, increase the risk of anthracycline cardiotoxicity. While epidemiologically established, the underlying mechanisms remain unclear, precluding identification of therapeutic targets. METHODS: Two-month-old Yucatan pigs (males and females) underwent aortic banding to induce LV pressure overload or no operation. After 4 months, animals received a low-risk cumulative dose of doxorubicin (5 weekly 1 mg/kg intravenous injections) or vehicle, generating four groups: (i) healthy controls (no LV overload, no doxorubicin), (ii) Dox (doxorubicin, no LV overload), (iii) Banding (B: LV overload, no doxorubicin), and (iv) B + Dox (LV overload plus doxorubicin). Cardiac function, structure, and metabolism were assessed over 8 months by cardiac magnetic resonance, magnetic resonance spectroscopy, and hybrid positron emission tomography/computed tomography. At study end, proteomics and mitochondrial structure and function were analysed. Complementary in vivo and ex vivo studies examined the mechanistic role of energetic imbalance. RESULTS: LV overload increased LV mass (P < .0001) and ejection fraction (P = .0081), with compensatory metabolic changes (drop in phosphocreatine (P = .022)). Low-risk Dox alone altered myocardial metabolism (increased glucose uptake, P = .014) but preserved cardiac function. In pigs with pre-existing LV pressure overload, doxorubicin increased mortality (P < .0001 vs all other groups), reduced left ventricular ejection fraction (LVEF) (P < .0001), increased fibrosis, and impaired mitochondrial respiration (P = .032). In HL-1 cardiomyocytes, reducing energy demand with mavacamten rescued cell viability under combined doxorubicin and hypertrophic stress. CONCLUSIONS: LV pressure overload increases myocardial susceptibility to anthracycline cardiotoxicity by inducing a high-energy-demand state. Anthracycline treatment, even at a low-risk dose, disrupts compensatory mechanisms in the pressure-overloaded heart, rapidly leading to cardiac dysfunction and heart failure. Preventive strategies targeting this metabolic vulnerability are urgently needed for patients with extant LV pressure overload (e.g. hypertension or valvular heart disease) who are undergoing anthracycline therapy.