Following a heart attack and reperfusion to restore blood flow, nearly half of patients have bleeding within the heart (hemorrhage). Hemorrhage is a strong predictor for both near-term loss of even more heart cells (e.g. reperfusion-induced death of cardiomyocytes resulting in myocardial infarct expansion) and long-term chronic heart failure and death. Diagnosis of hemorrhage is therefore essential for preventing near-term and long-term loss of heart function. Yet, current MRI for detection of hemorrhage is contraindicated until several days after a heart attack. Using proteomics, we have identified blood markers that now enable us to determine which heart attack patients have hemorrhage so that they can receive timely intervention (patent pending).