The Role of the Epinephrine Test in the Diagnosis and Management of Children Suspected of Having Congenital Long QT Syndrome

Abstract

The epinephrine test has been shown to be a powerful tool to predict the genotype of congenital long QT syndrome (LQTS). The aim of this study was to evaluate its role in the diagnosis and management of LQTS in children. The test (using the Shimizu protocol) was conducted in patients with some evidence of LQTS but in whom clinical and management decisions were challenging (n = 41, age 9.6 ± 3.9 years, 19 female). LQT1, LQT2, and negative responses to epinephrine were obtained in 16, 5, and 20 subjects, respectively. LQTS gene positivity was obtained in two subjects. Beta-blocker therapy was started in all subjects with a positive epinephrine response (n = 21) and in some negative responders because of their strong LQTS phenotype (n = 10). No therapy was given to the subset with less convincing features of LQTS who had also responded negatively to epinephrine (n = 10). Follow-up for 3.0 ± 2 years was uneventful in both management groups. Due to the discordance with genotyping, the epinephrine test cannot be used to diagnose genotype-positive LQTS but when used in combination with phenotype assessment and genetic screening, it could enable better management decisions.

Drug evaluation in cardiomyocytes derived from human induced pluripotent stem cells carrying a long QT syndrome type 2 mutation

“… 25 Indeed, stress testing of patients via sympathetic stimulation by the β-adrenoreceptor agonist, isoprenaline, has been employed to exacerbate and diagnose LQTS. 26 To determine whether arrhythmic events could be recapitulated in vitro , patient-specific and control cardiomyocytes were treated with isoprenaline ( Figure 5 ). In beating clusters, isoprenaline caused a similar reduction in FPD of control (20.4 ± 11.8%; data pooled for MAT–hiPSC, HF–hiPSC, and HUES7) and LQT2–hiPSC (24.1 ± 12.7%; P > 0.05; Figure 5 A ).…”

Secondly ECG recordings in the emergency room revealed Garenoxacin-induced abnormal QT interval prolongation in a patient with multiple syncopal attacks

“…In this patient, we prescribed metoprolol before obtaining the results of the genetic examination. This was because (a) beta-blocker is believed to be a first line medical treatment in most of the LQTS patients [18][19][20], and (b) results of the epinephrine infusion test and treadmill exercise test suggested either type-1 or type-2 LQTS [21][22][23]. Although magnitude of the QTc interval prolongation by the two tests were mild, type-3 LQTS seemed less likely because the QTc interval was not shortened by sympathetic stimulation.…”

Management of anaphylaxis and allergies in patients with long QT syndrome

“…21 In a systematic analysis, the epinephrine test, which is used to diagnose concealed iLQTS, no single episode of epinephrineinduced TdP or ventricular fibrillation occurred in more than 500 patients with iLQTS. 11 In contrast Clur et al 22 reported nonsustained ventricular tachycardia in patients with LQTS receiving epinephrine during the provocation test, despite the fact that the epinephrine bolus (0.1 mg/ kg) is much lower than the epinephrine dosage used for treating anaphylaxis. In a case report, the injection of epinephrine caused a marked prolongation of the QT interval, followed by polymorphic ventricular tachycardia, which could be terminated by direct cardioversion 23 ; therefore, LQTS was suspected.…”