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September 25, 2018 Circulation. 2018;138:e272–e391. DOI: 10.1161/CIR.0000000000000549 e334 CLINICAL STATEMENTS AND GUIDELINES 20% of patients with short QT syndrome including in KCNH2 (SQT1), KCNQ1 (SQT2), and KCNJ2 (SQT3).S7.9.1.5-4 Due to the rarity of the disease, genotype/phenotype correlations are unavailable, limiting the use of knowledge of genotype status. 8 VA IN THE STRUCTURALLY NORMAL HEART Recommendations for VA in the Structurally Normal Heart References that support the recommendations are summarized in Online Data Supplement 45. COR LOE Recommendations I B-R 1. In patients with symptomatic PVCs in an otherwise normal heart, treatment with a beta blocker or nondihydropyradine calcium channel blocker is useful to reduce recurrent arrhythmias and improve symptoms.S8-1,S8-2 IIa B-R 2. In patients with symptomatic VA in an otherwise normal heart, treatment with an antiarrhythmic medication is reasonable to reduce recurrent symptomatic arrhythmias and improve symptoms if beta blockers and nondihydropyradine calcium channel blockers are ineffective or not tolerated.S8-3,S8-4 Synopsis Most idiopathic VA are due to a focal mechanism of triggered activity or abnormal automaticity, some, notably interfascicular reentrant LV tachycardias, are due to reentry. The clinical manifestations of idiopathic VA are highly variable and range from benign, asymptomatic PVCs to sustained VT or even VF. On initial discovery, an evaluation for structural heart disease is warranted with physical examination, an ECG, and imaging, usually with echocardiography. In the absence of any abnormality or a family history of SCD, further assessment and treatment are guided by symptoms. If the patient is asymptomatic and does not have evidence of a cardiac channelopathy, reassurance as to the benign nature is sufficient. If the arrhythmia is suspected of being sufficiently frequent to cause ventricular dysfunction over time, periodic follow-up with reassessment of ventricular function is warranted (see Section 10.8). For mild symptoms, avoidance of aggravating factors such as excessive consumption of caffeine or sympathomimetic agents, may be sufficient. Therapy with a beta blocker or nondihydropyradine calcium channel blocker reduces symptoms for some patients. Class I antiarrhythmic medications can be effective, but those are generally avoided due to concerns for adverse effects. For patients who require arrhythmia suppression for whom antiarrhythmic medications are ineffective, not tolerated, or undesired, catheter ablation can be a highly effective treatment (see Section 9). The ablation strategy is to identify the site of origin manifested by the earliest site of electrical activation or, when this is not feasible, by pace-mapping. The most common site of origin for idiopathic VA is from the right ventricular outflow tract (RVOT) or the ostium of the LV, which is comprised of the oval opening of the LV to which the aorta is attached anteriorly and the left atrium is attached posteriorly. The likely origin can be reasonably predicted from the QRS morphology of the VA, which provides a good indication of the type of approach required and the likelihood of success and risks. Ablation failure is often related to the absence of the VA for mapping at the time of the procedure, or origin of the VA in an inaccessible region of the heart. These foci occasionally produce sustained monomorphic VT.S8-5–S8-7 Recommendation-Specific Supportive Text 1. In a randomized, double-blinded, placebo-controlled study of 52 patients with symptomatic VA and a mean PVC count of 21 407±1740 beats per 24 hours, atenolol significantly decreased symptom frequency (P =0.03) and PVC count (P =0.001), whereas placebo had no effect on PVC count (P =0.78) or average heart rate (P =0.44).S8-8 A prospective randomized comparison of antiarrhythmic medications versus catheter ablation, metoprolol or propafenone had modest efficacy to suppress RVOT VA although with a far higher rate of recurrence than catheter ablation.S8-9 2. In an RCT of 233 patients with ≥30 PVCs per hour, d-sotalol was shown to reduce frequent PVCs, but only racemic dl-sotalol is presently available.S8-10 In a prospective randomized comparison of antiarrhythmic medications versus catheter ablation, therapy with metoprolol or propafenone was shown to have modest efficacy when used to suppress RVOT PVCs although with a far higher rate of recurrence than catheter ablation.S8-9 Nondihydropyridine calcium channel blockers reduce arrhythmias.S8-1,S8-2,S8-11,S8-12 8.1 Outflow Tract and Atrioventricular Annular VA Recommendations for Outflow Tract VA References that support the recommendations are summarized in Online Data Supplement 46. COR LOE Recommendations I B-NR 1. In patients with symptomatic outflow tract VA in an otherwise normal heart for whom antiarrhythmic medications are ineffective, not tolerated, or not the patient’s preference, catheter ablation is useful.S8.1-1–S8.1-3 I B-NR 2. In patients with symptomatic outflow tract VT in an otherwise normal heart, a beta blocker or a calcium channel blocker is useful.S8.1-1–S8.1-3 Downloaded from http://ahajournals.org by on October 7, 2026