Dr. Kumar’s Take:
A study from the Western Denmark Heart Registry looked at how much LDL cholesterol (LDL-C) predicts future heart attack and stroke, depending on whether a patient already has coronary artery calcification (CAC). In this cohort of symptomatic patients sent for coronary CT angiography, LDL-C predicted events almost exclusively in the patients who already had calcium in their arteries. In patients with a calcium score of zero, LDL-C showed no association with events over the follow-up period. This is an observational registry study, not a trial of treatment, so it tells me who is at risk over the next few years, not who should stop a statin. Still, it is useful for framing how I talk about risk with a middle-aged patient in front of me.
Brief Summary:
Researchers analyzed 23,132 symptomatic patients who underwent coronary CT angiography. LDL-C was associated with future heart attack and ischemic stroke only in patients who already had coronary artery calcification (CAC > 0). Among patients with CAC = 0, LDL-C was not associated with those events. The principal findings were replicated in the Multi-Ethnic Study of Atherosclerosis.
Key Takeaways:
✔ LDL-C was associated with future events only when CAC was present.
✔ In patients with CAC = 0, no association was seen between LDL-C and future events.
✔ In patients with CAC = 0, diabetes, current smoking, and low HDL cholesterol were associated with future events.
✔ CAC status changed how informative LDL-C was for near-term risk.
Study Design:
This was an observational cohort study using data from the Western Denmark Heart Registry, a semi-national, multi-center registry with longitudinal registration of patient and procedure data. The researchers followed 23,132 consecutive symptomatic patients evaluated for coronary artery disease with coronary CT angiography (CTA). LDL-C was measured before the CTA. Patients were stratified by CAC > 0 and CAC = 0. Outcomes, heart attack and ischemic stroke, were identified through linkage among national registries covering all hospitals in Denmark, over a median follow-up of 4.3 years. Cox regression models were adjusted for baseline characteristics. The results were replicated in the Multi-Ethnic Study of Atherosclerosis.
Results:
✔ 552 patients had a first cardiovascular event during follow-up.
✔ In the overall population, each 38.7 mg/dL increase in LDL-C carried an adjusted hazard ratio of 1.14 (95% CI 1.04 to 1.24).
✔ In the 10,792 of 23,132 patients (47%) with CAC > 0, the adjusted hazard ratio per 38.7 mg/dL was 1.18 (95% CI 1.06 to 1.31).
✔ In the 12,340 of 23,132 patients (53%) with CAC = 0, there was no association: adjusted hazard ratio 1.02 (95% CI 0.87 to 1.18).
✔ LDL-C of 193 mg/dL or higher versus below 116 mg/dL carried an adjusted hazard ratio of 2.42 (95% CI 1.59 to 3.67) in patients with CAC > 0, and 0.92 (95% CI 0.48 to 1.79) in those with CAC = 0.
✔ In patients with CAC = 0, diabetes, current smoking, and low HDL cholesterol were associated with future events.
Why This Matters:
LDL-C is a well established causal risk factor for atherosclerotic cardiovascular disease, but this study shows its short-term predictive value depends on whether atherosclerosis has already taken hold. Over roughly five years of follow-up, LDL-C tracked with events in patients who had coronary calcium and not in those who did not. The authors frame this as information for individualized risk assessment in middle-aged patients with or without coronary atherosclerosis.
Related Studies and Research
The TG/HDL-C Ratio and Cardiovascular Risk: Explores the significance of the triglyceride-to-HDL cholesterol ratio in assessing cardiovascular risk and metabolic health.
Coronary Artery Calcium and Statin Allocation: Discusses how coronary artery calcium (CAC) scoring influences statin use and refines cardiovascular risk prediction.
Frequently Asked Questions
Does this mean LDL cholesterol is not important?
No. LDL-C is a causal risk factor in the development and progression of atherosclerosis, and this study does not contradict that. What it shows is that over about five years, LDL-C predicted heart attack and stroke in patients who already had coronary calcium, and did not in patients with a calcium score of zero.
Should I get a coronary artery calcium scan?
That is a decision to make with your own physician. This study was done in symptomatic patients already referred for coronary CT angiography, so it speaks to that setting rather than to screening the general population.
What if I have high LDL but no CAC?
In this cohort, patients with a calcium score of zero showed no association between LDL-C and heart attack or stroke over a median 4.3 years. In that same group, diabetes, current smoking, and low HDL cholesterol were associated with future events. This is an observational study over a limited follow-up window, and it does not test what happens if treatment is withheld.
Conclusion
LDL-C appeared almost exclusively associated with heart attack and ischemic stroke over roughly five years of follow-up in middle-aged patients who had evidence of coronary atherosclerosis, and not in those without it. In patients with a calcium score of zero, diabetes, current smoking, and low HDL cholesterol were the factors associated with future events.
I read this as an argument for using coronary calcium to refine how I interpret an LDL-C number in a middle-aged patient, not as an argument that LDL-C stops mattering.
