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Circulation. 2018;138:e272–e391. DOI: 10.1161/CIR.0000000000000549 September 25, 2018 e335 CLINICAL STATEMENTS AND GUIDELINES

Recommendation-Specific Supportive Text

1.	 In 1 RCT, catheter ablation was superior to antiarrhythmic medications at suppressing frequent PVCs arising from the RVOT.S8.1-4 Observational studies have shown that radiofrequency catheter ablation is effective in the treatment of idiopathic VA arising from the RVOT and LV outflow tract.S8.1-2,S8.1-5–S8.1-16 The site of ablation may be below or above the pulmonic valve in the RVOT.S8.1-9,S8.1-13 Although most RVOT VA can be ablated within the RV, 10% may require ablation within the pulmonic sinus cusps.S8.1-9 Serious complications are infrequent. For LV outflow tract VA, the site of ablation may be within the aortic cusp sinuses,S8.1-11,S8.1-14,S8.1-16 below the aortic valve,S8.1-2,S8.1-6 at the aorto-mitral continuityS8.1-1–S8.1-3 or on the epicardial surface of the LV summit.S8.1-3,S8.1-17,S8.1-18 The mitral and tricuspid annulae are less common sites of idiopathic VA, but these VA can also be effectively treated with catheter ablation.S8.1-1,S8.1-19,S8.1-20 Approximately 10% of idiopathic VA may arise from the summit of the LV. Some can be ablated from the great cardiac vein or the epicardial surface, but others arise from an inaccessible region in close proximity to the left coronary artery precluding effective ablation.S8.1-14 Intramural sites of origin are infrequent but may require ablation on both the endocardial and epicardial surfaces of the LV ostium.S8.1-3 Complications from ablation of outflow tract VA are infrequent, but bleeding complications related to arterial and venous access, pericardial tamponade, and damage to the coronary arteries can occur. 2.	 In a prospective randomized comparison of antiarrhythmic medications versus catheter ablation, metoprolol or propafenone was shown to have modest effectiveness when used to suppress RVOT PVCs, though with a far higher rate of recurrence than catheter ablation.S8.1-4 Non-dihydropyradine calcium channel blockers suppress arrhythmia in some patients.S8.1-4

8.2 Papillary Muscle VA

Recommendation for Papillary Muscle VA (PVCs and VT) References that support the recommendation are summarized in Online Data Supplement 47.

COR LOE Recommendation

I B-NR 1. In patients with symptomatic VA arising from the papillary muscles for whom antiarrhythmic medications are ineffective, not tolerated, or not the patient’s preference, catheter ablation is useful.S8.2-1–S8.2-5 Recommendation-Specific Supportive Text

1.	The papillary muscles of the LV or RV can be the site of origin of VA in the presence or absence of structural heart disease.S8.2-1–S8.2-5 Idiopathic left and right ventricular papillary muscle VA are most commonly PVCs and NSVT, and are usually exercise-related and may be induced by intravenous epinephrine or isoproterenol administration.S8.2-3 These arrhythmias have a focal, nonreentrant mechanism. Any of the 3 RV papillary muscles may be the site of origin and catheter ablation is usually effective.S8.2-2 In 1 study, successful ablation was achieved in all 8 patients with a reduction in PVC burden from 17±20% to 0.6±0.8%.S8.2-2 In the left ventricle, the site of origin may be either the posteromedial or the anterolateral papillary muscles.S8.2-1,S8.2-4,S8.2-5 Multiple VA QRS morphologies were observed in 47% of patients, and ablation on both sides of the papillary muscle is required in some patients.S8.2-4 Achieving adequate catheter stability can be challenging. Acute ablation success is high, but recurrences are more frequent than for idiopathic outflow tract VA. Serious complications, including valve injury, appear to be infrequent. The risks of catheter ablation include bleeding related to arterial and venous access and a low risk of pericardial tamponade.

8.3 Interfascicular Reentrant VT

(Belhassen Tachycardia)

Recommendations for Interfascicular Reentrant VT (Belhassen Tachycardia) References that support the recommendations are summarized in Online Data Supplement 48.

COR LOE Recommendations

I B-NR 1. In patients with verapamil-sensitive, idiopathic LVT related to interfascicular reentry for whom antiarrhythmic medications are ineffective, not tolerated, or not the patient’s preference, catheter ablation is useful.S8.3-1–S8.3-3

I B-NR 2. In patients with sustained hemodynamically tolerated verapamil-sensitive, idiopathic LVT related to interfascicular reentry, intravenous verapamil is recommended for VT termination.S8.3-3–S8.3-6

IIa C-LD 3. In patients with recurrent verapamil-sensitive idiopathic LVT, chronic therapy with oral verapamil can be useful.S8.3-7–S8.3-10

Recommendation-Specific Supportive Text

1.	 Idiopathic LVT is due to reentry involving a portion of the LV Purkinje system, usually the left posterior fascicle as the retrograde limb of the circuit and an incompletely defined segment of LV tissue as the anterograde limb, a portion of which is verapamil

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