Ingestion of Hibiscus sabdariffa L. (HSL) provides antioxidants with beneficial effects for several pathologies, with underlying oxidative stress. However excessive, chronic consumption of the antioxidant-rich diet with HSL in healthy rats induces reductive stress (RS) with damaging effects. The aim of this study was to evaluate if the consumption of an infusion of 6% HSL for two months alters the function and structure of the myocardium. 24 male Wistar rats were divided into three groups: Control (C), HLS infusion at 6% for two months (HSL 6%), and a washout group that received HSL 6 % for two months followed by two months of natural water (HSL ± 6%). Myocardial performance during ischemia-reperfusion (I/R) was evaluated by using the isolated Langendorff heart model, accompanied by surface electrocardiography and histopathological analysis. Chronic 6% HSL intake increased systolic pressure (p≤0.03), elevated coronary vascular resistance, depressed mechanical performance, led to bradycardia, and critical, extended asystolic/sinus pauses. Histopathology showed dense, permanent networks of interstitial and perivascular collagen encapsulating the hypertrophied cardiomyocytes. Therefore, the overload of antioxidant molecules provided by the HSL infusion leads to RS that increases myocardial interstitial fibrosis and disrupts coronary compliance and intercellular electrical coupling, leaving the heart vulnerable to ischemic stress.