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September 25, 2018 Circulation. 2018;138:e272–e391. DOI: 10.1161/CIR.0000000000000549 e326

CLINICAL STATEMENTS AND GUIDELINES

with recurrent syncope or cardiac arrest reported in 7% to 24% of patients.S7.9.1.1-44–S7.9.1.1-47 In high-risk patients, observational studies support effectiveness of the ICD in preventing SCD, with consideration of left cardiac sympathetic denervation to reduce the frequency of ICD shocks.S7.9.1.1-16,S7.9.1.1-48,S7.9.1.1-49 Left cardiac sympathetic denervation can reduce VA burden, but up to 27% of high-risk patients experience at least 1 recurrence.S7.9.1.1-16,S7.9.1.1-48,S7.9.1.1-50 Left cardiac sympathetic denervation may be more effective in patients with long QT syndrome type 1 and long QT syndrome type 3.S7.9.1.1-16 Complications related to left cardiac sympathetic denervation occur in 8% to 20% of patients.S7.9.1.1-48,S7.9.1.1-51 Syncope in patients with long QT syndrome may occur due to vasovagal syncope, noncompliance with medications, or proarrhythmia from concurrent medications.S7.9.1.1-5 Clinical evaluation that incorporates consideration of genotype, QTc interval, medication compliance, and shared decisionmaking regarding the need to change or escalate therapy is important. Use of additional medications is guided by long QT syndrome type. In long

Figure 9. Prevention of SCD in patients with long QT syndrome. Colors correspond to Class of Recommendation in Table 1. See Section 7.9.1.1 for discussion. *ICD candidacy as determined by functional status, life expectancy, or patient preference. †High-risk patients with LQTS include those with QTc >500 ms, genotypes LQT2 and LQT3, females with genotype LQT2, <40 years of age, onset of symptoms at <10 years of age, and patients with recurrent syncope. ICD indicates implantable cardioverter-defibrillator; LQTS, long QT syndrome; VT, ventricular tachycardia.

Figure 10. Long QT syndrome type 1.

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