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Circulation. 2018;138:e272–e391. DOI: 10.1161/CIR.0000000000000549 September 25, 2018 e301 CLINICAL STATEMENTS AND GUIDELINES 12. Epinephrine may increase coronary and cerebral perfusion pressure during CPR because of its vasoconstrictive effects. High doses of epinephrine (0.1 to 0.2 mg/kg IV, as opposed to a standard dose of 1 mg) have been studied in RCTs. In out-of-hospital cardiac arrest unresponsive to defibrillation, administration of high-dose epinephrine improved survival to hospital admission, but there was no difference compared to standard dose epinephrine in survival to hospital discharge.S6-19 There was also no improvement in long-term survival.S6-21 Of note, the administration of vasopressin is no longer recommended in the most recent advanced cardiovascular life support algorithms.S6-1 13. Magnesium may suppress automaticity, suppress early and late after-depolarizations, and inhibit calcium flux into cardiomyocytes. It is effective in suppressing VA related to acquired long QT syndrome. However, 2 RCTs that investigated the use of intravenous magnesium in patients with cardiac arrest and refractory VF found no benefit.S6-27,S6-28 In a study of out-of-hospital cardiac arrest, administration of 2 to 4 g magnesium intravenously did not improve survival to hospital admission.S6-27 In a similar study involving inpatient cardiac arrest, magnesium did not improve return of spontaneous circulation, survival to 24 hours, or survival to hospital discharge.S6-28 There are exceptions such as marked hypokalemia or medication-induced torsades de pointes in which administration of intravenous magnesium is warranted. 14. Several studies have tested the hypothesis that prophylactic administration of antiarrhythmic medications could reduce the incidence of post- MI VA and lead to better outcomes. One metaanalysis assessed studies in which beta blockers, class I antiarrhythmic agents such as lidocaine and procainamide, and amiodarone were given in the setting of AMI. The routine use of lidocaine and procainamide was associated with increased mortality, whereas beta blockers were associated with a significantly lower mortality rate.S6-16 Limited data with amiodarone appeared to be promising, but a subsequent RCT involving 1073 patients found that administration of high-dose amiodarone led to a higher mortality rate, although a moderate dose of amiodarone was not superior to placebo.S6-29 15. With a stable, wide QRS complex tachycardia, differentiation between SVT with aberrancy and VT is often possible by review of the patient’s history and the 12-lead ECG during tachycardia. Patients with wide QRS complex tachycardia and known structural heart disease should be presumed to have VT until proven otherwise. Administration of a calcium channel blocker such as verapamil to a patient with VT may result in severe hypotension or syncope.S6-31 The exception is verapamil-sensitive VT (interfascicular reentry) that occurs in a structurally normal heart; but this is often difficult to recognize on initial presentation.S6-30 7 ONGOING MANAGEMENT OF VA AND SCD RISK RELATED TO SPECIFIC DISEASE STATES 7.1 Ischemic Heart Disease 7.1.1 Secondary Prevention of SCD in Patients With Ischemic Heart Disease Recommendations for Secondary Prevention of SCD in Patients With Ischemic Heart Disease References that support the recommendations are summarized in Online Data Supplements 17 and 18. COR LOE Recommendations I B-R 1. In patients with ischemic heart disease, who either survive SCA due to VT/VF or experience hemodynamically unstable VT (LOE: B-R) S7.1.1-1–S7.1.1-4 or stable sustained VT (LOE: B-NR) S7.1.1-5 not due to reversible causes, an ICD is recommended if meaningful survival greater than 1 year is expected. B-NR Value Statement: Intermediate Value (LOE: B-R) 2. A transvenous ICD provides intermediate value in the secondary prevention of SCD particularly when the patient’s risk of death due to a VA is deemed high and the risk of nonarrhythmic death (either cardiac or noncardiac) is deemed low based on the patient’s burden of comorbidities and functional status.S7.1.1-6 I B-NR 3. In patients with ischemic heart disease and unexplained syncope who have inducible sustained monomorphic VT on electrophysiological study, an ICD is recommended if meaningful survival of greater than 1 year is expected.S7.1.1-7 Downloaded from http://ahajournals.org by on October 7, 2026