Updated by Konstantin A. Krychtiuk, 20 August 2021
In patients who have suffered an AMI, an LDL-C reduction of at least 50% from baseline together with an LDL-C goal of <55 mg/dL (<1.4 mmol/L) are recommended (both goals need to be achieved).  High-intensity statins such as atorvastatin 40-80 mg or rosuvastatin 20-40 mg usually result in an LDL-C reduction of around 50%. If target levels cannot be reached with maximally dosed high-intensity statins, ezetimibe should be added; for further reduction of LDL-C levels, a PCSK9-inhibitor is recommended. (Table 1)
Table 1. Lipid-Lowering treatment in Secondary Prevention – Key messages
Treatment Goals: LDL<55 mg/dL (<1.4 mmol/L) AND at least a 50% reduction from baseline values.
|Available Drugs||Dosage||Expected LDL-C reduction||Comment|
|Atorvastatin||40 mg, 80 mg once daily||≥ 50%|
|Rosuvastatin||20mg, 40 mg once daily||≥ 50%|
|Ezetemibe||10 mg once daily||15-20% as add-on||refer to specialist|
|Evolocumab||140 mg s.c. every other week; 420 mg s.c. monthly||50-60% as add-on||refer to specialist|
|Alirocumab||75 mg, or 150 mg s.c., every other week||50-60% as add-on||refer to specialist|
|Inclisiran||284 mg s.c., on day 1, day 90 and every 6 months||40-50% as add-on||No CV outcome trials available yet|
|Bempedoic acid||180 mg once daily||23% as monotherapy
35% in combination with ezetimibe
|No CV outcome trials available yet|
Optimal lipid management for patients after an acute myocardial infarction (AMI) is of paramount importance. Prompt initiation of high-intensity statin therapy is strongly recommended for every patient after an AMI – regardless of baseline LDL-cholesterol levels, – within 1-4 days of the index event. The type and dose chosen should achieve LDL-C values of <55mg/dL (<1.4 mmol/L) AND a reduction of at least 50%. This includes atorvastatin 40-80mg and rosuvastatin 20-40mg (see Table 1) .
LDL-C levels should be re-checked after 6-8 weeks. If patients fail to reach target levels, ezetimibe 10mg once daily should be added and is associated with improved outcomes. In patients with high LDL-C unlikely to reach goal with a statin alone, an statin-ezetimibe combination treatment should be considered upfront during index hospitalization. 
Patients with an established ASCVD and especially those in the early phase after an AMI who present with persistently elevated levels of LDL-C despite treatment at the the maximum tolerated statin dose combined with ezetemibe or patients with true statin intolerance, should receive treatment with a PCSK-9 inhibitor to further improve outcome.  Such patients should in addition be referred to a lipid specialist for screening for familial hypercholesterolemia.
Patients that experience a second vascular event within two years while taking maximum-tolerated statin therapy, an LDL-C goal of < 40mg/dL may be considered.
By inhibiting the HMG-CoA-reductase activity in hepatocytes, statins reduce hepatic cholesterol synthesis, leading to lower intracellular cholesterol levels. This in turn, causes LDL-receptor upregulation on the hepatocyte surface, which results in increased uptake thereby further decreases the LDL-C levels in the circulation. The degree of this action is dependent on the dose and type of statin used (see Table 1).
As it is one of the most intensively investigated drugs in cardiovascular medicine, the underlying evidence can only be partially discussed here. The Cholesterol Treatment Trialists (CTT) data including >170,000 participants from 26 randomized controlled trials (RCTs) suggest that a 40 mg/dL reduction in LDL-C results in a 10% reduction of all-cause and a 20% drop of CAD mortality as well as a 23% reduction in major coronary events . These benefits were consistent in all subgroups and even more significant after a longer period of treatment.
In secondary prevention, particularly after an AMI, the beneficial effects of statins are particularly significant involving other (pleiotropic) statin effects including potentially anti-inflammatory or plaque-stabilizing effects .
Muscle symptoms ranging from myalgia without any rise in creatine kinase levels to rhabdomyolysis, are the most commonly described adverse effects and the principal reason for statin discontinuation with potential detrimental effect on the patient. The reported frequency varies considerably, with evidence suggesting a 5% occurrence rate . It is not recommended to routinely check creatine kinase levels after a statin therapy is started. Diagnosis should be based on clinical observation: whether symptoms disappear after discontinuation and re-appear after re-challenge with at least three statin types and various dosages. In secondary prevention especially, it is of utmost importance to secure the diagnosis of statin-associated muscle symptoms (SAMS) with a structured work-up and treat the few truly affected patients on the maximum tolerated statin dose combined with non-statin lipid-lowering therapies to attain the recommended LDL-C targets. Further information can be found in the Consensus Statement of the European Atherosclerosis Society . A systematic review found that the incidence of drug-induced hepatotoxicity in patients taking statins is unknown , but it is recommended to have the liver enzymes (alanine transaminase - ALT) checked every 8–12 weeks after a statin treatment is started or the dose has been increased.
As a cholesterol absorption inhibitor, Ezetemibe inhibits intestinal cholesterol uptake and thereby reduces cholesterol transport to the liver. This causes the LDL-receptor upregulation which in turn, lowers the circulating LDL-C levels. Monotherapy with Ezetemibe results in lower LDL-levels, around 15-22%, while adding statin therapy causes a further 15-20% drop. In IMPROVE-IT, Ezetemibe was added to 40 mg Simvastatin in more than 18,000 patients after ACS, this led to an additional LDL-reduction, which resulted in another slight yet statistically significant reduction in cardiovascular events .
Bempedoic acid is a novel, oral small molecule inhibiting cholesterol synthesis within the liver by blocking adenosine triphosphate citrate lyase, an enzyme upstream of HMG-CoA reductase. In contrast to statins, inhibition of cholesterol biosynthesis is liver-specific which results in reduced side effects, in particular a reduction of muscle symptoms as compared to statins. It was recently approved in the US and Europe. Addition of bempedoic acid (180mg once daily) to maximally tolerated statin therapy reduced LDL-C levels by 16.5 and 17.2%, while administration as a combination therapy with ezetimibe was associated with a 36.2% reduction. A phase III cardiovascular outcome trial (CLEAR-Outcomes) in statin-intolerant patients is currently being undertaken (NCT02993406; clinicaltrials.gov).
After LDL-uptake, PCSK-9 binds to the now intracellular LDL-receptors causing lysosomal degradation. Inhibiting this protein reduces LDL-receptor degradation, thereby causing an increased LDL-receptor expression on the hepatocyte which decreases the circulating LDL-levels. PCSK-9 inhibitors are injected subcutaneously every other week or every month. The efficacy in reducing LDL-C is very high with reported reductions of 50-60% independently of any background therapy. Two phase III randomized controlled cardiovascular outcome trials evaluating the two available PCKS-9 antibody treatments suggested a reduction of cardiovascular events upon treatment with PCSK9-inhibitors.  
Therefore, a PCSK9 inhibitor should be prescribed for patients who have suffered an AMI with persistent high LDL-C despite treatment at the maximum tolerated statin dose, in combination with ezetimibe, or for patients with confirmed statin intolerance.
Inclisiran is a small, interfering RNA agent (siRNA) and reduces hepatic PCSK-9 synthesis. It is injected subcutaneously on day 1, day 90 and and every 6 months thereafter. In the ORION study program, this therapeutic regime resulted in an approximately 40-50% reduction in circulating LDL-C levels.  As of now, no data from outcome trials are available, a phase III cardiovascular outcome trial is currently being conducted (ORION-4; NCT03705234; clinicaltrials.gov).