If someone with heart disease has a very low 'bad' cholesterol level when they’re admitted for a heart attack, they might be more likely to die in the hospital or later on — but this link goes away when you account for how sick they were overall.

Even when people with heart disease have really low 'bad' cholesterol, some still have heart attacks — showing that low cholesterol alone doesn’t eliminate all heart risks.

If someone with heart disease has a heart attack, fixing blocked arteries might help more if their 'bad' cholesterol was already low when they arrived at the hospital.

In middle-aged and older adults in China who aren’t at high risk for heart disease, having either too low or too high 'bad' cholesterol (LDL) is linked to a higher chance of dying from any cause or heart problems — the safest zone seems to be around 106 to 118 mg/dL.

If you have heart disease from clogged arteries, getting your bad cholesterol down to around 56 mg/dL instead of 66 mg/dL can cut your risk of heart attacks or strokes by about a third over three years. For every 32 people treated this way, one person avoids a major heart problem.

A lot of people with heart problems don't actually have high LDL cholesterol — about half of them have normal or even low levels — so maybe LDL isn't the main cause of heart disease after all.