Cholesterol: the race to the bottom

Aggressive LDL-C Lowering and the Brain: Impact on Risk for Dementia and Hemorrhagic Stroke: A Scientific Statement From the American Heart Association

The objective of this scientific statement is to evaluate contemporary evidence that either supports or refutes the conclusion that aggressive low-density lipoprotein cholesterol lowering or lipid lowering exerts toxic effects on the brain, leading to cognitive impairment or dementia or hemorrhagic stroke. The writing group used literature reviews, references to published clinical and epidemiology studies, clinical and public health guidelines, authoritative statements, and expert opinion to summarize existing evidence and to identify gaps in current knowledge. Although some retrospective, case control, and prospective longitudinal studies suggest that statins and low-density lipoprotein cholesterol lowering are associated with cognitive impairment or dementia, the preponderance of observational studies and data from randomized trials do not support this conclusion. The risk of a hemorrhagic stroke associated with statin therapy in patients without a history of cerebrovascular disease is nonsignificant, and achieving very low levels of low-density lipoprotein cholesterol does not increase that risk. Data reflecting the risk of hemorrhagic stroke with lipid-lowering treatment among patients with a history of hemorrhagic stroke are not robust and require additional focused study.

Targeting PCSK9 With Antibodies and Gene Silencing to Reduce LDL Cholesterol

The discovery of PCSK9 and its role in regulating the low-density lipoprotein (LDL) receptor, and the effect of loss-of-function mutations of its gene, identified it as a therapeutic target in 2006. Fully humanized monoclonal antibodies to PCSK9 (alirocumab and evolocumab) proved effective for lowering LDL cholesterol and subsequently for reducing atherosclerotic events in large outcome trials. Suppressing PCSK9 synthesis via gene silencing using inclisiran, a small interfering RNA, is another approach that effectively reduces LDL cholesterol, and a cardiovascular outcome trial is in progress. These treatments are given subcutaneously on a background of maximally tolerated statin treatment and are long-lasting: dosing is once or twice a month, self-administered, for alirocumab and evolocumab, and every 6 months for inclisiran, in the clinic, with an extra dose at 3 months in the initial year of therapy. These 3 agents produce mean LDL reductions of about 55% with no important adverse effects detectable to date. They are indicated in patients with atherosclerotic vascular disease or familial hypercholesterolemia who cannot achieve LDL cholesterol targets with maximally tolerated statin treatment. Such therapy can produce very low plasma LDL cholesterol and PCSK9, but there is no evidence this is harmful. Introduction into clinical practice has been impeded by economic considerations. The barrier to their use has not been scientific or medical, but rather the impact on healthcare resources. Prices have been reduced, but whether they are now cost-effective varies from country to country.

Impact of Atorvastatin on Skeletal Muscle Mitochondrial Activity, Locomotion and Axonal Excitability-Evidence from ApoE-/- Mice

The cardiovascular benefit of statins is well established. However, only 20% of high-risk patients remain adequately adherent after 5 years of treatment. Among reasons for discontinuation, statin associated-muscle pain symptoms are the most prevalent. Aim of the present study was to evaluate the impact of high dose atorvastatin on skeletal muscle mitochondrial activity, aerobic and anaerobic exercise, and axonal excitability in a murine model of atherosclerosis. ApoE^-/- mice were fed 12 weeks a high-fat high-cholesterol diet alone or containing atorvastatin (40 mg/Kg/day). Outcomes were the evaluation of muscle mitochondrial functionality, locomotion, grip test, and axonal excitability (compound action potential recording analysis of Aα motor propioceptive, Aβ mechanoceptive and C nociceptive fibres). Atorvastatin led to a reduction in muscle mitochondrial biogenesis and mitochondrial ATP production. It did not affect muscular strength but led to a time-dependent motor impairment. Atorvastatin altered the responsiveness of mechanoceptive and nociceptive fibres, respectively, the Aβ and C fibres. These findings point out to a mild sensitization on mechanical, tactile and pain sensitivity. In conclusion, although the prevalence of muscular side effects from statins may be overestimated, understanding of the underlying mechanisms can help improve the therapeutic approach and reassure adherence in patients needing-to-be-treated.