An elevated concentration of what analyte decreases the risk of coronary heart disease?

High-density lipoprotein (HDL) cholesterol is known as "good" cholesterol because it plays a protective role in cardiovascular health. Elevated levels of HDL cholesterol are associated with a decreased risk of coronary heart disease. This is primarily due to HDL’s functionality in transporting cholesterol from the arteries and tissues back to the liver, where it can be metabolized and excreted. This reverse cholesterol transport process aids in reducing the build-up of arterial plaque, thus lowering the risk of atherosclerosis and related heart conditions.

In contrast, low-density lipoprotein (LDL) cholesterol is often referred to as "bad" cholesterol because high levels can lead to plaque accumulation in arteries, increasing the risk of heart disease. Triglycerides, elevated levels of which can also be a risk factor for heart disease, are a type of fat found in the blood and can signal metabolic issues when present in high concentrations. Total cholesterol includes both HDL and LDL components and does not distinguish between the protective and harmful types of cholesterol; thus, it is not a definitive marker alone for coronary heart disease risk.

Consequently, an elevation in HDL cholesterol is a clear indicator of a protective factor against coronary heart disease, making it the correct answer in this context.