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Circulation. 2018;138:e272–e391. DOI: 10.1161/CIR.0000000000000549 September 25, 2018 e307 CLINICAL STATEMENTS AND GUIDELINES

mortality among the patients with NICM who received amiodarone (P =0.07).S7.1.3-20 2.	 Patients with prior MI may present with frequent episodes of sustained monomorphic VT or recurrent VF episodes that are initiated by PVCs arising from Purkinje Fibers in the peri-infarct zone. VA storms are  associated with increased mortality.S7.1.3-12 The arrhythmia substrate is usually in the subendocardium. The randomized VANISH (Ventricular Tachycardia Ablation versus Escalated Antiarrhythmic Drug Therapy in Ischemic Heart Disease) trialS7.1.3-4 compared escalating antiarrhythmic medication therapy versus catheter ablation for patients with prior MI  and recurrent sustained monomorphic VT despite antiarrhythmic medications. The primary outcome, a composite of death, VT storm, or ICD shocks occurred in 59.1% in the ablation group and in 68.5% in the escalated-therapy group. There was no difference in mortality between the groups. Recurrent ICD shocks and VT storm and treatment-related adverse events were lower in the ablation group. In a subgroup analysis, patients having VT on amiodarone had better outcomes with ablation compared with increasing amiodarone or adding mexiletine to amiodarone. For patients receiving medications other than amiodarone, catheter ablation did not reduce the risk of ICD shocks or VT storm compared with switching to amiodarone. Although recurrent VT after catheter ablation is associated with increased mortality,S7.1.3-9 whether mortality is reduced by catheter ablation has not been established. Procedural complications occur in approximately 6% of patients, most of which are related to vascular access but stroke, tamponade, and atrioventricular block can occur. Procedure mortality is <1% in experienced centers.S7.1.3-4,S7.1.3-9

Sustained monomorphic VT often occurs as occasional isolated episodes in patients with prior MI. Several nonrandomized studies have shown that catheter ablation reduces recurrent VT or ICD shocks.S7.1.3-5,S7.1.3-7,S7.1.3-8 A meta-analysis of 5 VT ablation studiesS7.1.3-5 reported that VT recurred in 35% of patients after catheter ablation compared with 55% on antiarrhythmic medications. In a multicenter study of catheter ablationS7.1.3-7 for patients with  ≥3 episodes of sustained VT in the prior 6 months, 53% were free from recurrent VT at 6 months follow-up; the median number of VT episodes was reduced from 11.5 to 0. Superiority of ablation over escalating medication therapy was shown in the composite endpoint of death, VT storm, or ICD shocks by the VANISH trial.S7.1.3-4 3.	 Patients with prior MI who develop sustained monomorphic VT often have recurrent episodes. The VTACH (Ventricular Tachycardia Ablation in Addition to Implantable Defibrillators in Coronary Heart Disease) trialS7.1.3-11 randomized patients undergoing ICD implantation for stable sustained monomorphic VT, who had not failed antiarrhythmic medication therapy, to catheter ablation versus ICD implantation alone. At 2 years, any VT had recurred in 53% of the ablation group and 71% of the control group. Ablation prolonged the time to recurrent VT from a median of 5.9 months to 18.6 months.S7.1.3-11 Several nonrandomized studies have shown that catheter ablation reduces the risk of recurrent VT or ICD shocks in patients with sustained VT related to prior MI.S7.1.3-5,S7.1.3-7,S7.1.3-8 In a multicenter study of catheter ablationS7.1.3-7 for patients with  ≥3 episodes of sustained VT in the prior 6 months, 53% were free from recurrent VT at 6 months follow-up; the median number of VT episodes was reduced from 11.5 to 0. A meta-analysis of 5 VT ablation studiesS7.1.3-5 reported that VT recurred in 35% of patients after catheter ablation compared with 55% on antiarrhythmic medications. Another study of 63 patients with recurrent VT after MI demonstrated acute success with catheter ablation in 83% of mappable VTs and 40% of nonmappable VTs.S7.1.3-8 Superiority of ablation over escalating medication therapy for patients with recurrent VT despite antiarrhythmic medications was shown by the VANISH trial.S7.1.3-4 See Section 5.6. 4.	 CASTS7.1.3-21 demonstrated higher rates of mortality or nonfatal cardiac arrest in post-MI patients treated with encainide or flecainide when used to suppress PVCs and NSVT.S7.1.3-13 Propafenone is associated with increased mortality in SCA survivors compared with beta blockers, amiodarone, and the ICD.S7.1.3-22

5.	 Implantation of an ICD prior to achieving suppression of frequent or incessant VA places the patient at high risk of repetitive shocks, which can be psychologically detrimental and has been associated with increased mortality.S7.1.3-23,S7.1.3-24 6.	 Sustained monomorphic VT in the setting of prior MI is typically due to scar-related reentry and is not due to acute ischemia. Although it may be appropriate to recommend revascularization when another indication for revascularization exists, revascularization alone is unlikely to reduce the recurrence of monomorphic VT and specific therapies such as antiarrhythmic medications or ablation may be needed to prevent recurrence.S7.1.3-16 On the contrary, revascularization might be beneficial in patients with

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