Intensive lowering of LDL cholesterol to below 55 mg/dL reduces major adverse cardiovascular events by 33% and improves renal outcomes without increasing safety risks in patients with established atherosclerotic cardiovascular disease.

Study: Achieved LDL-C levels <55 mg/dL and cardiac events in patients and lesions harbouring lipid-rich plaque phenotypes

This study found that for heart patients with especially fatty, dangerous plaques in their arteries, lowering LDL cholesterol below 55 mg/dL greatly reduced their risk of heart attacks and other serious heart problems. But for patients without these fatty plaques, lowering LDL that much didn’t help.

Study: Lipid plaque density index as a phenotypic plaque feature which benefits from achieving LDL-C <55 mg/dL: Observations from the REASSURE-NIRS Multi-center Registry

This study found that lowering LDL cholesterol below 55 mg/dL helps reduce heart problems only in patients whose arteries have a lot of fatty buildup — not in everyone. So it supports the idea that this treatment works, but only for some people.

Study: Long-term outcomes according to absolute value vs. percentage reduction in low-density lipoprotein cholesterol levels after acute myocardial infarction

This study found that lowering LDL cholesterol too much—below 55 mg/dL—didn’t help heart patients any more than keeping it around 55–69 mg/dL, and might even be less safe. It also didn’t look at kidney health or safety risks like the claim says.