Final answer:
Chest pain is a sign of decreased oxygen to the heart muscle, often associated with coronary heart disease and angina.
Step-by-step explanation:
A sign or symptom of decreased oxygen to the heart muscle is chest pain. This condition, known as angina, indicates that heart muscle fibers are not receiving enough oxygen, which can be a symptom of coronary heart disease. The heart requires a steady supply of oxygen to function properly, and this is delivered through the coronary arteries. The buildup of plaque within these arteries can reduce blood flow, leading to oxygen deprivation in the heart muscle during stress or physical activity, which manifests as chest pain. It's important to note that other conditions can also cause chest pain, and it should be evaluated by a healthcare professional.