The Troponin I test is a critical, life-saving blood test used to rapidly diagnose a heart attack. Troponin I is a protein that is found only in your heart muscle. When the heart is damaged, it releases this protein into the bloodstream. This test is one of the most sensitive and specific markers available, allowing for a fast and accurate diagnosis in an emergency setting. A simple blood draw is all that is required. This test provides the fast, definitive information your doctor needs to protect your heart and make critical, time-sensitive decisions.