The primary uses of simvastatin are to treat dyslipidemia and to prevent atherosclerosis-related complications such as stroke and heart attacks in those who are at high risk. It is recommended to be used as an addition to a low-cholesterol diet.
In the Scandinavian Simvastatin Survival Study (a placebo-controlled, randomized clinical trial of five years' duration), simvastatin reduced overall mortality in people with existing cardiovascular disease and high LDL cholesterol by 30% and reduced cardiovascular mortality by 42%. The risks of heart attack, stroke, or needing a coronary revascularization procedure were reduced by 37%, 28%, and 37%, respectively.
The Heart Protection Study evaluated the effects of simvastatin in people with risk factors including existing cardiovascular disease, diabetes, or stroke, but having relatively low LDL cholesterol. In this trial, which lasted 5.4 years, overall mortality was reduced by 13% and cardiovascular mortality was reduced by 18%. People receiving simvastatin experienced 38% fewer nonfatal heart attacks and 25% fewer strokes.
Simvastatin has been used to explore whether statins have an effect on delaying on the onset and progression of age-related macular degeneration (AMD). Results from one trial showed participants assigned to simvastatin had lower odds (0.51 OR) of having AMD progression at three years compared to those assigned to placebo, though the results were not significant. Overall, evidence is insufficient to conclude that simvastatin has an effect in delaying the onset and progression of AMD.