A Reappraisal of the Risks and Benefits of Treating to Target with Cholesterol Lowering Drugs

Atherosclerotic cardiovascular disease (CVD) is the number one cause of death globally, and lipid modification, particularly lowering of low density lipoprotein cholesterol (LDLc), is one of the cornerstones of prevention and treatment. However, even after lowering of LDLc to conventional goals, a sizeable number of patients continue to suffer cardiovascular events. More aggressive lowering of LDLc and optimization of other lipid parameters like triglycerides (TG) and high density lipoprotein cholesterol (HDLc) have been proposed as two potential strategies to address this residual risk. These strategies entail use of maximal doses of highly potent HMG CoA reductase inhibitors (statins) and combination therapy with other lipid modifying agents. Though statins in general are fairly well tolerated, adverse events like myopathy are dose related. There are further risks with combination therapy. In this article, we review the adverse effects of lipid modifying agents used alone and in combination and weigh these effects against the evidence demonstrating their efficacy in reducing cardiovascular events, cardiovascular mortality, and all cause mortality. For patients with established CVD, statins are the only group of drugs that have shown consistent reductions in hard outcomes. Though more aggressive lipid lowering with high dose potent statins can reduce rates of non fatal events and need for interventions, the incremental mortality benefits remain unclear, and their use is associated with a higher rate of drug related adverse effects. Myopathy and renal events have been a significant concern with the use of high potency statin drugs, in particular simvastatin and rosuvastatin. For patients who have not reached target LDL levels or have residual lipid abnormalities on maximal doses of statins, the addition of other agents has not been shown to improve clinical outcomes and carries an increased risk of adverse events. The clinical benefits of drugs to raise HDLc remain unproven. In patients without known cardiovascular disease, there is conflicting evidence as to the benefits of aggressive pursuit of numerical lipid targets, particularly with respect to all cause mortality. Certainly, in statin intolerant patients, alternative agents with a low side effect profile are desirable. Bile acid sequestrants are an effective and safe choice for decreasing LDLc, and omega-3 fatty acids are safe agents to decrease TG. There remains an obvious need to design and carry out large scale studies to help determine which agents, when combined with statins, have the greatest benefit on cardiovascular disease with the least added risk. These studies should be designed to assess the impact on clinical outcomes rather than surrogate endpoints, and require a comprehensive assessment and reporting of safety outcomes.