Why Everyone Should Get a Calcium CT Scan?
Powerful screening tool provides a window into your cardiovascular health
You breathe a sigh of relief - your LDL cholesterol is a cool 90, well below that pesky 120 mg/dL threshold set by the AHA. "Woohoo, I'm in the clear!" you exclaim, high-fiving yourself in the mirror. Sadly, you are not out of the woods yet!
For individuals at elevated risk of cardiovascular disease (CAD), a more nuanced method of assessing cardiovascular risk is necessary, extending beyond the mere examination of LDL and HDL (high-density lipoprotein) cholesterol levels. Unlike LDL and HDL levels, which serve as indirect markers of cardiovascular risk, cardiologists will often emphasize that the coronary artery calcium (CAC) score directly indicates the presence and severity of atherosclerosis in the coronary arteries. A coronary calcium scan can measure the amount of calcium in your heart arteries, which is the CAC score. A coronary calcium scan is a special computerized tomography (CT) scan of the heart. It looks for calcium deposits in the heart arteries, and may reveal coronary artery disease before you have symptoms. For instance, patients can have low LDL-C levels but still have high CAC scores. Higher CAC scores indicate a greater burden of coronary artery disease (more calcium deposits) and are associated with an increased risk of adverse cardiovascular events such as heart attacks and strokes.
The figures shown above are from research that associates coronary plaque with LDL-C levels and rates of cardiovascular disease events among symptomatic patients. They show that even patients with LDL-C levels < 77 mg/dL have high CAC scores >100. In addition, according to the study, 46.2% of patients with LDL-C ≥190 mg/dL had a CAC score of 0. The authors found that the prevalence of calcified plaque had no clear association with LDL-C levels. Overall, absence of plaque (low CAC score) was associated with low event rates1 across all LDL-C levels, with any detectable plaque being associated with 2 to 3 times higher event rates. From the figures, it is clear that a patient with an LDL-C level < 77 had a higher cardiovascular event rate than a patient with an LDL-C level > 190 if their CAC score was higher. The bottom line is that that LDL-C alone does not fully determine the presence and extent of coronary artery calcification. In summary, CAC score is a stronger predictor of cardiovascular risk, regardless of LDL-C levels. A high CAC score (e.g. >300) confers high cardiovascular risk, similar to those with established heart disease, while a CAC score of 0 is associated with very low cardiovascular event rates, even in those with severely elevated LDL-C. CAC burden can be used to stratify risk among various other lipid disorders, allowing for the identification of individuals with lowest and highest event rates.
Now, how do you get a coronary calcium scan? Unfortunately, most primary care physicians still look at only LDL-C and HDL-C levels as markers of coronary risk and will rarely bring up the CAC score. I would strongly suggest that you advocate for yourself and insist on the coronary calcium scan procedure. In most states, a physician's prescription may be required and most insurances will not pay for the test. Fortunately, the test is relatively low cost ($50 to $200 in most cities).
The test's excellent predictive value for atherosclerotic cardiovascular disease (ASCVD) and mortality, coupled with its noninvasive nature makes this a no-brainer, given the large number of asymptomatic individuals in the high and intermediate risk categories in the United States is large (includes all diabetic patients and genetic causes of hyperlipidemia).
Let me leave you with a story that hits close to home. On the insistence of a cardiologist friend, I persuaded my skeptical primary care physician to order a CAC scan, despite my seemingly innocuous LDL-C reading of 120. My doc, bless his heart, tried to dissuade me, citing my "not-too-high" cholesterol as a get-out-of-jail-free card. But I persisted, and the scan revealed a CAC score alarmingly north of 100, prompting an immediate prescription for a 10mg statin regimen. He was genuinely blindsided by the high score, chalking it up to my "South Asian genes." From this experience, three invaluable lessons emerged, seared into my consciousness: First, never be afraid to advocate for yourself. Don't assume the experts always know best – sometimes, you've got to trust your gut and push for the tests or treatments you need. Second, LDL-C is not the be-all and end-all of heart health. As my story illustrates, those numbers can lull you into a false sense of security, masking underlying issues that more comprehensive tests can uncover. And finally, for my fellow South Asians out there, this is a wake-up call. We can't afford to be complacent when it comes to our cardiac risk factors. Our genetic predisposition demands extra vigilance, a topic I'll dive into in a future post.
Takeaway: If you are over 40 and have a family history of cardiovascular disease, it's essential to prioritize getting a Calcium CT scan done as soon as possible, particularly if you're not currently using statin therapy. Fortunately, the test is relatively low cost ($50 to $200 in most cities). A CAC score of 0 or near 0 is a positive sign, but if your score indicates otherwise, starting statin therapy may be necessary.