In November 2018 the ACC/AHA guidelines strongly embraced coronary calcium scanning for better assessing the risk of intermediate risk patients.
I discuss this welcome change here.
My most recent post discusses the importance of using coronary calcium scans in youngish patients.
In July 2019 I summarized coronary calcium scanning with the humbly named The Ultimate Guide To The Coronary Artery Calcium Scan (Score) Circa 2019
In earlier posts I referenced the ACC/AHA ASCVD risk estimator tool as the starting point but if I have information on my patient’s CACS I use a new and improved tool called the MESA risk score calculator.
It is available online and through an app for Apple and Android (search in the app store on “MESA Risk Score” for the (free) download.)
The MESA tool allows you to easily calculate how the CACS effects you or your patient’s 10 year risk of ASCVD.
To use the score you will need information on the following risk factors:
age, gender, race/ethnicity, diabetes (yes/no), current smoker (yes/no), total and HDL cholesterol, use of lipid lowering medication (yes/no), systolic blood pressure (mmHg), use of anti-hypertensive medication (yes/no), any family history of heart attack in first degree relative (parent/sibling/child) (yes/no), and a coronary artery calcium score (Agatston units).
In many cases the CACS dramatically lowers or increases the risk estimate.
In this example a 64 year old man with no discernible risk factors has a CACS of 175
The 10 year risk of a CHD event almost doubles from 4.7% to 7.6% when the CACS is added to the standard risk factors and moves into a range where we need much more aggressive risk factor modification.
On the other hand if we enter in zero for this same patient the risk drops to a very low 1.9%.
It’s also instructive to adjust different variables. For example, if we change the family history of heart attack (parents, siblings, or children) from no to yes, this same patient’s risk jumps to 7.2% (2.6% with zero calcium score and to 10.4% with CACS 175.)
It can also be used to help modify risk-enhancing behaviors. For example if you click smoker instead of non-smoker the risk goes from 4.7% to 7.5%. Thus, you can tell your smoking patient that his risk is halved if he stops.
Discussions on the value of tighter BP control can also be informed by the calculator. For example, if our 64 year old’s systolic blood pressure was 160 his risk has increased to 6.8%.
How Does Your CACS Compare To Your Peers?
A separate calculator let’s you see exactly where your score stands in comparison individuals with your same age, gender, and ethnicity
The Coronary Artery Calcium (CAC) Score Reference Values web tool will provide the estimated probability of non-zero calcium, and the 25th, 50th, 75th, and 90th percentiles of the calcium score distribution for a particular age, gender and race. Additionally, if an observed calcium score is entered the program will provide the estimated percentile for this particular score. These reference values are based on participants in the MESA study who were free of clinical cardiovascular disease and treated diabetes at baseline. These participants were between 45-84 years of age, and identified themselves as White, African-American, Hispanic, or Chinese. The current tool is thus applicable only for these four race/ethnicity categories and within this age range.
The calculator tells us that 75% of 64 year old white males have a zero CACS and that the average CACS is 61.
Unlike SAT scores or Echo Board scores you don’t want your CACS percentile status to be high. Scores >75th percentile typically move you to a higher risk category, whereas scores <25th percentile move you to a lower risk category, often with significant therapeutic implications.
Scores between the 25th and 75th percentile typically don’t significantly change the risk calculation.
Exploring Gender Differences In CACS
If we change the gender from male to female on our 64 year old the risk drops considerably from 4.7% down to 3.3%. This graph demonstrates that over 20% of women between the ages of 75 and 84 years will have zero calcium scores.
The graph for men in that same range shows that only around 10% will have a zero CACS.
I’ve been asked what the upper limit is for CACS but I don’t think there is one. I’ve seen numerous patients with scores in the high two thousands and these graphs show individuals in the lowest age decile having scores over 2981.
If you want to be proactive about the cardiovascular health of yourself or a loved one, download the MESA app and evaluate your risk. Ask your doctor if a CACS will help refine that risk further.
Miscellaneous Posts On CAC