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Medical Therapy - Statins

The first study to suggest a beneficial effect of lipid lowering therapy did not appear until 2004 (24). Since that time, there have been additional studies that have also shown perioperative statin therapy reduces the incidence of post-operative cardiac events. For example, in a RCT, Durazzo et al (26) reported a 50% reduction in the in-hospital mortality in vascular patients receiving 20mg of atrovastatin started 7 days pre-operatively. Similarly, the study by Lindenauer et al (27) found that the risk of perioperative death was reduced 30% in patients who had a statin started within 2 days of surgery. Furthermore, using RCRI to indicate peri-operative risk, these authors found that the protective effect of statins was even more pronounced in higher risk patients.

The mechanisms that contribute to the beneficial effects of statins on perioperative cardiac events are independent of their lipid lowering effect and include enhanced functional integrity of vascular endothelium and plaque stabilization, as well as reduction in vascular inflammation, platelet aggregation and thrombus formation (44). Since the evidence today suggests that plaque rupture in an atherosclerotic vessel is one of the mechanisms responsible for perioperative myocardial infarction, stabilization of the plaque becomes an important preventive measure. Thus, acute initiation of statin therapy in the perioperative period is useful in patients with indications for long term statin therapy such as hypercholesteremia, vascular disease (regardless of the baseline cholesterol level) and the metabolic syndrome. (44). (The metabolic syndrome is defined as the presence of 3 or more risk factors for atherosclerosis, ie cardiovascular, peripheral vascular, & cerebrovascular disease and Type 2 diabetes. Risk factors include abdominal obesity, elevated triglycerides ≥150mg/dl, reduced HDL {<40 mg/dl for men & ,50mg/dl for women}, elevated blood pressure {≥130/85} and elevated fasting glucose ≥100mg/dl). In addition, Biccard et al (45) have suggested that patients with ≥2 risk factors should be started on perioperative statin therapy. At present, the optimal time for initiation is unknown but evidence suggests that some of the beneficial effects occur rapidly, even when administered in the immediate preoperative period. (44)

In light of the beneficial effects of statins on plaque stabilization, combination therapy with perioperative beta blockade may prove to be better than each agent alone. In addition to improving the myocardial oxygen supply and demand ratio, beta blockade may help to decrease the likelihood of plaque rupture by decreasing the mechanical stresses within the vessel wall that occur secondary to perioperative increases in sympathetic tone. Early evidence suggests that combination therapy is beneficial although more RCTs are needed.

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