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Circulation. 2018;138:e272–e391. DOI: 10.1161/CIR.0000000000000549 September 25, 2018 e337 CLINICAL STATEMENTS AND GUIDELINES

a very high risk of recurrent VF, an ICD is indicated to prevent SCD. Catheter ablation of the triggering focus has proved to be highly effective in eliminating the repetitive PVCs which induce VF in these patients.S8.4-11 During a median postprocedural follow-up of 63 months, 7 (18%) of 38 patients undergoing catheter ablation of idiopathic VF induced by short coupled PVCs experienced VF recurrence at a median follow-up of 4 months. Five of these 7 patients underwent repeat ablation without VF recurrence. Thus, although catheter ablation is very effective in idiopathic VF, the recurrence risk remains substantial after an apparently successful procedure and the patient should be protected with an ICD. The subcutaneous ICD may not be a good therapy for these patients due to the higher risk of T-wave oversensing seenin this population; however, data are limited.S8.4-10 3.	 Idiopathic VF may be initiated by PVCs that arise from the outflow tracts or the His-Purkinje system within either the right ventricle or left ventricle.S8.4-11,S8.4-14,S8.4-19–S8.4-21 Some patients have clusters of VF episodes (electrical storm) that typically present as PVCs initiating polymorphic VT/VF. The PVCs usually have a consistent QRS morphology and a short coupling interval and can be targeted for ablation to control the arrhythmia.S8.4-11 For PVCs from the Purkinje system, the ablation target is a high-frequency Purkinje potential preceding the PVCs. When episodes are induced by short-coupled PVCs arising from the outflow tracts, the ablation target is the site of earliest ventricular activation. Patients with idiopathic VF often have periods of frequent VT/VF interspersed with periods of relative quiescence.S8.4-11,S8.4-14 To maximize the probability of successful ablation, the procedure is best performed during periods of frequent PVCs. Less-frequent episodes of VF may be amenable to ablation if frequent PVCs with a consistent QRS morphology are present. When the PVCs can be identified, ablation is highly successful, but late recurrences are observed in approximately 10% of patients such that implantation of an ICD is prudent even if ablation is acutely successful. The risks of catheter ablation include bleeding at the site of arterial or venous access and a small risk of pericardial tamponade. Therapy with quinidine acutely and chronically can suppress recurrent VF episodes in some patients.S8.4-22 9 PVC-INDUCED CARDIOMYOPATHY

Recommendations for PVC-Induced Cardiomyopathy References that support the recommendations are summarized in Online Data Supplement 50.

COR LOE Recommendations

I B-NR 1. For patients who require arrhythmia suppression for symptoms or declining ventricular function suspected to be due to frequent PVCs (generally >15% of beats and predominately of 1 morphology) and for whom antiarrhythmic medications are ineffective, not tolerated, or not the patient’s preference, catheter ablation is useful.S9-1,S9-2

IIa B-NR 2. In patients with PVC-induced cardiomyopathy, pharmacological treatment (eg, beta blocker, amiodarone) is reasonable to reduce recurrent arrhythmias and improve symptoms and LV function.S9-3,S9-4

Recommendation-Specific Supportive Text

1.	 Frequent PVCs (usually >15% of the total number of beats) may produce a reversible form of LV dysfunction.S9-5–S9-18 However, it is sometimes difficult to ascertain whether the PVCs caused LV dysfunction or whether progressive LV dysfunction caused frequent PVCs. LV dysfunction has been associated with greater PVC burden (>10% and usually >20%), NSVT, a retrograde  P-wave after the PVCs, and interpolated PVCs.S9-6,S9-15 In a prospective study of catheter ablation for PVC-induced cardiomyopathy, ablation was completely successful in 80% of patients.S9-19 LV function normalized within 6 months in 82% of the 22 patients who had depressed ventricular dysfunction at baseline. Thus, frequent PVCs may be a reversible cause of LV dysfunction that can be effectively treated with catheter ablation. It is often difficult to determine if apparent LV dysfunction reflects impaired LV function or inability to accurately assess LV function due to the frequent ectopic activity. In patients who have a high density of PVCs with normal ventricular function, optimal treatment and surveillance for prevention and detection of decline in ventricular function have not been established. 2.	 In a double-blind parallel study of 30 patients with or without ischemic heart disease with >30 PVCs per hour comparing sotalol to propranolol, proarrhythmic effects were present in 1 patient on sotalol. There was no significant difference in suppression of PVCs (sotalol 65%, propranolol 44%), with reduction in ventricular couplets being 99% for sotalol and 49% for propranolol. There was a significant increase in QTc in patients on sotalol.S9-20 In a double-blind, randomized,

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