Are Canadian guidelines for cholesterol lowering in high-risk patients optimal?

Recent Canadian lipid guidelines recommend that all high-risk patients receive medication to reduce low density lipoprotein cholesterol (LDL-C) below 2.5 mmol/L. The recently published Reversal of Atherosclerosis with Aggressive Lipid Lowering (REVERSAL) and Pravastatin or Atorvastatin Evaluation and Infection Therapy (PROVE IT) studies compared strategies of cholesterol lowering with atorvastatin 80 mg versus pravastatin 40 mg. Atorvastatin halted the progression of atherosclerosis (whereas atherosclerosis progressed in the patients receiving pravastatin), and resulted in a 16% reduction in the primary composite end point (all-cause death, myocardial infarction, unstable angina, revascularization and stroke) compared with the pravastatin-treated group. In the PROVE IT trial, LDL-C was reduced by atorvastatin to 1.6 mmol/L and by pravastatin to 2.46 mmol/L. Although lower LDL-C levels are one explanation for the improved outcomes with atorvastatin, pleiotropic differences of the two statins, such as their effects on inflammation and coagulation, cannot be excluded. Until trials are completed that compare outcomes from LDL-C lowering to different targets with the same statin, it is premature to recommend changes to the current Canadian guidelines. However, future recommendations may suggest much lower LDL-C targets than those currently recommended.