Advances in the measurement of troponin in blood using highly sensitive assays has improved time to diagnosis of heart attacks but increases in troponin in patients presenting with chest pain that do not rise above diagnostic thresholds can lead to uncertainty for clinical care and management. Furthermore, the moderate ability of troponin to predict future mortality and cardiovascular events can be improved upon. We have discovered in human blood a novel protein called APRIL that identifies patients with chest pain whom might be at high risk of future adverse events, that are not identified by troponin. APRIL appears to complement and add to the prognostic ability of troponin in patients with chest pain. This study will clarify the potential diagnostic and prognostic utility of APRIL in patients with cardiovascular disease and seek to confirm its potential use as a clinical partner to troponin measurement in this high risk group.