If you've had heart problems before, aiming to get your 'bad' cholesterol really low—below 55—cuts your risk of another heart issue by about a third compared to keeping it just under 70.

If you've already had heart problems, keeping your 'bad' cholesterol really low—below 55—might help prevent future heart attacks or strokes compared to aiming for a higher level.

For people who already have heart disease, aiming to get their 'bad' cholesterol (LDL) below 55 mg/dL cuts their risk of serious heart problems by about one-third over three years compared to aiming for below 70 mg/dL — and it doesn’t seem to cause more side effects.

Keeping your 'bad' cholesterol really low—below 55 mg/dL—might give your heart and blood vessels the best protection against clogged arteries and heart problems.

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.

Lowering bad cholesterol really aggressively might not help people live longer because while it prevents heart attacks, it could also cause other problems that balance things out.