The heart is a voracious consumer of energy, more than any other organ. Like every other cell and organ in the body, the heart’s energy currency is adenosine triphosphate, or ATP. The heart runs through approximately six kilograms of ATP every day, which is 20 to 30 times its own weight. The heart must generate all of the ATP it needs in real time.
Under normal circumstances, both glucose (sugars) and free fatty acids (fats) are fuels for metabolism in the heart. In heart disease, oxygen levels available to cells may be lower than usual, and as a result the heart may rely to a greater extent on fatty acids to make energy. However, ATP generation is less efficient because 10% to 15% more oxygen is required to generate the same amount of ATP from fatty acids as compared to glucose.