Chapter 21 Marini Acute Coronary Syndromes

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CHAPTER 21 • Acute Coronary Syndromes

properties. β -Blockers have been shown to improve survival in all patient subgroups, including those in whom they are traditionally considered as relatively contraindicated (dia- betics, chronic obstructive pulmonary disease [COPD], heart failure, and peripheral vascular disease). Just as with ACEI therapy, β -blockers should be started in small dosage and gradually increased as tolerated. They must be used with caution in those with severe COPD or bron- chospasm, overt CHF, bradyarrhythmias, and brittle diabetes. 5. Aldosterone Antagonists: Eplerenone (an aldosterone receptor antagonist) was reported to reduce mortality in post-MI patients with severe LV systolic dysfunction already taking ACEI and β -blockers in the EPHESUS trial. Spironolactone is another agent with similar action that could potentially be used in these patients. Although cheaper in cost, spirono- lactone has more unpleasant endocrine side effects compared to eplerenone. These include hirsutism in women and painful gynecomas- tia in men. Therefore, all post-MI patients with LVEF less than 40%, symptomatic CHF, or diabetes mellitus and without renal failure (creatinine <2.5 mg%) or hyperkalemia (potas- sium >5.0 mmol/L) should be considered for an aldosterone antagonist if they are already on an ACEI. Creatinine and potassium must be monitored closely in all patients receiving an aldosterone antagonist. 6. Statin and Alternative Cholesterol Man- agement: Multiple, secondary prevention tri- als have all shown reduction of reinfarction and death in post-MI patients receiving high-dose statins. Lowering LDL cholesterol level is the primary goal; however, it can be reached. Ben- efit may accrue even in those with LDL-c less than 100 mg/dL. Current guidelines suggest achieving a goal LDL-c level less than 70 mg/dL in these patients, with use of powerful statin drugs like atorvastatin or rosuvastatin. One must monitor these patients periodically for side effects like myalgias, myositis, and drug-induced hepatitis. Statin therapy should be continued indefinitely if well tolerated. If the patient expe- riences side effects, lower doses or a switch to a less powerful statin like pravastatin seems indicated. Failure to reach LDL targets despite dietary and lifestyle changes and tolerated doses

of statin should prompt consideration of adding other classes of drug such as the fibrates and dietary cholesterol blockers (e.g., ezetimibe [Zetia] or bile salt sequestrants). The dramatic LDL-lowering potency (and extraordinarily high cost) of recently introduced human monoclonal antibody agents (alirocumab [Praluent] and evo- locumab [Repatha]) suggests that a new era of cholesterol management may be dawning. 7. Antiarrhythmic Agents: Routine use of pro- phylactic antiarrhythmic therapy is not neces- sary in patients with AMI. Even though PVCs and nonsustained VT are markers of increased riskof SCD, especially in the setting of decreased LV systolic function, their suppression with antiarrhythmic agents may actually result in increased mortality because of their proarrhyth- mic potential (CAST trial findings). The best way to reduce risk of SCD in these patients is by means of quick reperfusion, and judicious use of β -blockers and ACEI, as already dis- cussed. β -Blockers and ACEI have been shown to reduce SCD over the long term through posi- tive ventricular remodeling, which also ensures electrical stability. Antiplatelet agents (aspirin, clopidogrel) and statins have also been shown to reduce SCD long term in post-MI patients. There is epidemiological evidence supporting the use of fish oils rich in omega-3 fatty acids, which have been shown to reduce the risk of SCD. In patients with STEMI resuscitated from VF arrest and in those with symptomatic sustained VT, one may consider amiodarone, which is not only very effective in suppressing ventricular and supraventricular arrhythmias but also one of the safest antiarrhythmic agents from the standpoint of proarrhythmia. It may also be indicated for prophylaxis against recur- rent AF, in which case it is usually given for 8 to 12 weeks. In dire emergencies like resusci- tated VF arrest, sustained VT, and symptomatic supraventricular tachycardia (SVT) includ- ing AF, it is usually given intravenously in the dose of 150 mg bolus followed by infusion of 1 mg/min for 6 hours, followed by infusion of 0.5 mg/min for 18 hours. This is usually followed by oral amiodarone therapy lasting for 3 to 6 months or longer. 8. Calcium Channel Blockers: Although they are effective for controlling acute hyperten- sion, reversing coronary spasm, and relieving