In high-risk patients, a low or even a score of zero is not a reliable tool to rule out coronary artery disease and can be misleading. Here are two examples of severe coronary artery disease despite having a coronary calcium score of zero. These cases emphasise the importance of proper use of coronary calcium score in daily practice.
Case 1: This is a case of a patient who has presented with a suspected heart attack. CT Coronary Angiogram has shown a severe narrowing in the Right Coronary Artery (RCA) with no identifiable calcium. A subsequent invasive angiogram (bottom right picture) confirmed the RCA’s occlusion. This is the case of a young smoker with other risk factors for coronary artery disease.
Case 2 (inappropriate use of Coronary Calcium Score): This case is a 38-year-old man with untreated hypertension and high cholesterol as well as chest pain. Unfortunately, he was investigated with a Coronary Calcium Score as his initial test, which was “zero”, as seen in the scans. However, his chest pain continued, and a subsequent positive stress test led to a CT Coronary Angiogram. CTCA showed a severe (critical) narrowing at the proximal portion of the Left Anterior Descending (LAD) Artery. A subsequent invasive coronary angiogram (shown below) confirmed a subtotal occlusion of the proximal LAD artery, which was treated successfully with angioplasty. Here, the CAC score was used wrongly to investigate “chest pain”. CAC score is designed to be used only in asymptomatic people and should never be used to investigate the cause of chest pain.