Intermittent fasting (IF) is a lifestyle growing in our societies. IF prevents metabolic syndrome in humans and cardiac remodeling in models of myocardial infarction.

In this preliminary study, we wanted to determine whether IF confers cardioprotection involving improvement in energy metabolism during ischemia-reperfusion injury.

10-week-old Wistar rats (Charles River) were separated into two groups: a control group (CTL, n=6) and IF group (IF, n=6). The CTL group was fed ad libitum and the IF group was fed every other day for 19 weeks. Weight and food intake were monitored weekly. At the end of the diet, intraperitoneal glucose tolerance test (IPGTT) and cardiac magnetic resonance imaging (MRI; Pharmascan, Siemens) were performed. Myocardial tolerance to ischemia-reperfusion was then studied on the Langendorff-perfused isolated heart model, with simultaneous study of cardiac function and energy metabolism by P-31 magnetic resonance spectrometry (MRS; Avance 400 9.4T, Bruker). Acute stress was induced by a period of partial ischemia at 0.4mL/min/g, at 37°C for 32min. The hearts were then reperfused for 32min. Energy metabolism was monitored by measuring adenosine triphosphate (ATP).

If female rats had similar weight gain to CTL despite a significant (P<0.01) decrease of food efficiency (0.017±0.003 vs 0.036±0.003). The area under the curve of IPGTT was significantly (P<0.05) decreased in IF compared with CTL (15329±1244 vs 17655±1958). MRI showed no difference in morphology or cardiac function between the two groups but showed a drastic reduction (P<0.05) in myocardial perfusion in IF compared with CTL (4.49±2.36mL/g/min vs 8.16±2.04mL/g/min). At reperfusion, the percentage recovery of cardiac function (Fig. 1A) was significantly higher (P<0.01) in IF compared with CTL (67.0±8.7% vs 10.5±13.7%). In parallel, myocardial post-ischemic ATP recovery (Fig. 1B) was significantly higher (P<0.05) in IF compared to CTL (77.7±4.8% vs 42.3±22.1%).

In this preliminary study, we show for the first time that IF protects the heart against an episode of ischemia, probably by optimally maintaining energy metabolism, particularly ATP. A decrease in myocardial perfusion and an improvement in carbohydrate homeostasis were also observed. These results suggest an improved diffusion of oxygen from the capillary to the mitochondria. This preliminary study opens up new avenues for exploring the preventive impact of dietary patterns in cardiometabolic pathologies.