Is a calcium score of my heart worth doing?
Unsure whether to start taking statins? A calcium score can help inform that decision: a score of zero is highly reassuring, while a score above 300 is reason for a serious conversation with your cardiologist.
A calcium score is a CT scan of your heart that measures how much calcium has built up in the walls of your coronary arteries. More calcium generally means more atherosclerosis and a higher risk of a heart attack. The score is only meaningful when compared with people of your own age and sex: a score of 100 in a 45-year-old man is very different from the same score in a 70-year-old woman, as the large MESA study of more than 6,000 participants shows1.
The gain in predictive accuracy is statistically demonstrable, but modest. Adding the calcium score to standard risk calculations improves accuracy by an average of just 0.036 on a scale of 0 to 1, according to a meta-analysis in JAMA Internal Medicine2. There are downsides as well: the scan delivers a small radiation dose and sometimes picks up incidental abnormalities in the lungs that lead to unnecessary follow-up investigations. Of the people whose risk category was upgraded to moderate or high on the basis of their score, 85.5 to 96.4 percent still had no cardiac event in the following 5 to 10 years. Reclassification to a higher risk category therefore often causes unwarranted anxiety.
The real clinical value lies at the two extremes. A score of zero, meaning no calcium visible, is highly reassuring: depending on your age group, it rules out clinically significant coronary artery disease in 94 to 100 percent of cases3,4. That can be a reason to defer preventive medication such as statins for the time being. On the other hand, people with no known heart disease but a score above 300 were found to have the same level of risk as people who had already had a heart attack or undergone a coronary intervention5. That is a serious signal, even though no proven treatment protocol specifically for this group yet exists.
Major guidelines, including the ACC/AHA, ESC/EAS and Canadian guidelines from 2019 to 2021, recognise the calcium score as a tool to help decide whether or not to start statins or aspirin6,4. It is explicitly intended as a personal conversation between you and your doctor, not as a screening programme for everyone. For the large middle group with scores somewhere in between, the score is less decisive, and the risk of unwarranted anxiety and possible follow-up investigations must be weighed in the balance.
One meta-analysis (PMID 35467692) forms the core of the evidence on predictive gain and downsides. Other claims come from large observational cohort studies (MESA, PMID 16365194) and guideline publications. There are no randomised trials demonstrating that the use of the calcium score leads to better clinical outcomes. All associations are observational in nature unless stated otherwise.