If you have calcium buildup in your heart's arteries, the link between your 'bad' cholesterol and heart problems changes — it’s stronger or weaker depending on that calcium.

If you're a middle-aged person with signs of heart disease and calcium in your arteries, having very high 'bad' cholesterol makes your risk of heart problems more than double. But if your arteries are clean, even sky-high cholesterol doesn’t seem to increase your risk.

If a middle-aged person has higher 'bad' cholesterol, they're more likely to have buildup in their heart arteries — every 38.7-point rise means about a 17% higher chance of early heart disease signs, even if they already have symptoms.

If a middle-aged person has heart symptoms but no calcium buildup in their arteries, things like diabetes, smoking, and low 'good' cholesterol are linked to future heart problems — but their 'bad' cholesterol level doesn’t seem to matter, which might mean other non-plaque-related issues are causing the heart trouble.

If a middle-aged person has very high 'bad' cholesterol but feels fine, they’re more than 2.6 times as likely to have early signs of heart artery buildup — even if everything else about their health is accounted for.

Even if someone has high 'bad' cholesterol, it doesn’t seem to reliably predict how much plaque is building up in their heart arteries — some people with very high levels have clean arteries, and their risk of heart events stays low if their scan shows no calcium.