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Abstract A 23‐year‐old female had been suffering from recurrent syncopal episodes during sleep since her childhood. She had a family history of sudden death and her QTc interval was remarkably prolonged to 537 ms A Holter ECG revealed torsade de pointes, corresponding to syncope. She was started on mexiletine and her QTc interval shortened. Her symptoms were controlled after β‐blockers and Ca‐blockers were added. A genetic analysis with a next generation sequencer identified a frameshift mutation at the C terminus of the KCNH2 gene. Here we present a type 2 long QT syndrome case in which mexiletine was effective.

A 23‐year‐old female had been suffering from recurrent syncopal episodes during sleep since her childhood. She had a family history of sudden death and her QTc interval was remarkably prolonged to 537 ms A Holter ECG revealed torsade de pointes, corresponding to syncope. She was started on mexiletine and her QTc interval shortened. Her symptoms were controlled after β‐blockers and Ca‐blockers were added. A genetic analysis with a next generation sequencer identified a frameshift mutation at the C terminus of the KCNH2 gene. Here we present a type 2 long QT syndrome case in which mexiletine was effective. [ABSTRACT FROM AUTHOR]

A 76-year-old man who had been diagnosed with long-QT syndrome type 2 had frequent syncopal attacks. The electrocardiogram was monitored, and frequent torsades de pointes (TdP) was detected despite administration of conventional medications: oral propranolol, verapamil, intravenous magnesium sulfate, verapamil, and lidocaine. In contrast, 2 μg/kg/min landiolol could completely suppress TdP. Subsequently, an implantable cardioverter defibrillator was placed, and he was diagnosed with silent myocardial ischemia using myocardial perfusion scintigraphy and coronary angiography. This is the first case report wherein landiolol effectively suppressed TdP due to long-QT syndrome with silent myocardial ischemia.

Background Due to its availability, atenolol is the primary beta-blocker used in Australia for children with long QT syndrome. There is limited data on long-term follow-up of its use. Methods A single-tertiary-center, retrospective, observational study investigating all children and adolescents who had genetically proven long QT syndrome type 1 (LQT1) and type 2 (LQT2) was conducted. Their pretreatment exercise tests were evaluated for QTc intervals into the recovery phase of exercise. Results Eighty six patients were identified (LQT1, 67, and LQT2, 19) from 2004 to 2014. The majority (86%) of patients were initially referred for family screening. Atenolol was administered at a mean dose of 1.58 ± 0.51 mg/kg/day. During the median follow-up period of 4.29 years, only one proband developed ventricular arrhythmia whilst taking atenolol, No patient had cardiac arrest or aborted cardiac arrest. With respect to side effects of atenolol, only two patients had intolerable side effects necessitating changes of medication. Evaluation of exercise tests (pretreatment) demonstrated that corrected QT (QTc) intervals at 2–3 min into the recovery phase of exercise were significantly prolonged for LQT1 patients. LQT1 patients with transmembrane mutation had longer QTc intervals than their C-terminus mutation counterparts, reaching statistical significance at 3 min into the recovery phase of exercise. Conclusions Atenolol is an effective treatment for genetically proven LQT1 and LQT2 children and adolescents, with good tolerability. In LQT1 patients, QTc intervals at 2–3 min into the recovery phase of exercise were significantly prolonged, particularly in patients with transmembrane mutations. [ABSTRACT FROM AUTHOR]

A 76-year-old man who had been diagnosed with long-QT syndrome type 2 had frequent syncopal attacks. The electrocardiogram was monitored, and frequent torsades de pointes (TdP) was detected despite administration of conventional medications: oral propranolol, verapamil, intravenous magnesium sulfate, verapamil, and lidocaine. In contrast, 2 μg/kg/min landiolol could completely suppress TdP. Subsequently, an implantable cardioverter defibrillator was placed, and he was diagnosed with silent myocardial ischemia using myocardial perfusion scintigraphy and coronary angiography. This is the first case report wherein landiolol effectively suppressed TdP due to long-QT syndrome with silent myocardial ischemia. [ABSTRACT FROM AUTHOR]

We describe a patient with torsades de pointes (TdP) who was implanted with cardiac resynchronization therapy defibrillator (CRT-D). At the time of CRT-D implantation, left ventricular (LV) epicardial pacing exacerbated TdPs and developed into electrical storm, which was triggered even by biventricular pacing. We needed to inactivate the LV lead for 2 weeks. At the next device check testing of LV pacing still induced TdPs, whe reas biventricular pacing did not. After starting the continuous biventricular pacing no ventricular arrhythmias happened, and furthermore the QT intervals prolonged by LV pacing were obviously shortened only after 2 weeks as ventricular systolic function recovered. Then even continuous LV alone pacing induced no TdP. These findings indicate novel electrical effects of cardiac resynchronization therapy.

Potassium channel blockers are sometimes effective in the rhythm management of persistent atrial fibrillation. However, on rare occasions, a life-threatening episode of torsade de pointes develops during treatment with these agents. Among several precautions against this tragedy, preventing exaggerated QT prolongation is of paramount importance. One of the difficulties in monitoring the QT interval during atrial fibrillation is the fact that its length varies depending not only on the fluctuating preceding intervals, but on other factors such as neurohumoral activation. In fact, even at the same preceding RR interval, the QT interval may vary from day to night, between atrial fibrillation and sinus rhythm. Accordingly, the QTc interval may not be a reliable parameter for predicting proarrhythmic events. As the result, close monitoring of the QT interval itself, just like INR monitoring during warfarin treatment, is mandatory both before and during treatment with these agents.

A 7-year-old boy presented at our hospital with syncope. At birth, electrocardiography had shown a long QT interval with torsade de pointes (TdP). Congenital long QT syndrome (LQTS) had been diagnosed by genetic testing, and was successfully controlled with oral propranolol. At age 7, TdP had recurred with syncope. Electrocardiography revealed a prominent long QT interval with T-wave alternans. The propranolol dose was increased, but TdP remained uncontrolled. A cardioverter-defibrillator (ICD) was implanted epicardially, and TdP completely resolved with atrial pacing. We report this rare case of ICD implantation in a child with LQTS. [ABSTRACT FROM AUTHOR]

Background: The gene KCNE1 encodes the β‐subunit of cardiac voltage‐gated K+ channels and causes long QT syndrome (LQTS). LQTS is characterized by the prolongation of QT interval and lethal arrhythmias such as torsade de pointes (TdP). A KCNE1 polymorphism, D85N, has been shown to modify the phenotype of LQTS through a loss‐of‐function effect on both KCNQ1 and KCNH2 channels when co‐expressed and reconstituted in a heterologous expression system. Methods: A screening for the D85N polymorphism was performed in 355 LQTS families with mutations in KCNQ1, KCNH2, or SCN5A. Among the probands who had a heterozygous status with the polymorphism, we focused on a family with a KCNH2 mutation (E58K), a N‐terminal missense mutation, and examined the clinical significance of this polymorphism. We also conducted biophysical assays to analyze the effect of the polymorphism in mammalian cells. Results: In 355 probands, we found 14 probands (3.9%) who had a heterozygous compound status with the D85N polymorphism. In the family with a KCNE1‐D85N polymorphism and a KCNH2‐E58K mutation, the proband and her daughter carried both the KCNH2 mutation and the KCNE1‐D85N polymorphism. They experienced repetitive syncope and TdP. Two sons of the proband had either KCNH2‐E58K mutation or KCNE1‐D85N, but were asymptomatic. Biophysical assays of KCNE1‐D85N with KCNH2‐E58K variants produced a larger reduction in the reconstituted IKr currents compared to co‐expression with wild‐type KCNE1. Conclusions: The KCNE1‐D85N polymorphism modified the clinical features of LQTS patients. [ABSTRACT FROM AUTHOR]

We describe a patient with torsades de pointes (TdP) who was implanted with cardiac resynchronization therapy defibrillator (CRT-D). At the time of CRT-D implantation, left ventricular (LV) epicardial pacing exacerbated TdPs and developed into electrical storm, which was triggered even by biventricular pacing. We needed to inactivate the LV lead for 2 weeks. At the next device check testing of LV pacing still induced TdPs, whe reas biventricular pacing did not. After starting the continuous biventricular pacing no ventricular arrhythmias happened, and furthermore the QT intervals prolonged by LV pacing were obviously shortened only after 2 weeks as ventricular systolic function recovered. Then even continuous LV alone pacing induced no TdP. These findings indicate novel electrical effects of cardiac resynchronization therapy. [Copyright &y& Elsevier]

Abstract: Potassium channel blockers are sometimes effective in the rhythm management of persistent atrial fibrillation. However, on rare occasions, a life-threatening episode of torsade de pointes develops during treatment with these agents. Among several precautions against this tragedy, preventing exaggerated QT prolongation is of paramount importance. One of the difficulties in monitoring the QT interval during atrial fibrillation is the fact that its length varies depending not only on the fluctuating preceding intervals, but on other factors such as neurohumoral activation. In fact, even at the same preceding RR interval, the QT interval may vary from day to night, between atrial fibrillation and sinus rhythm. Accordingly, the QTc interval may not be a reliable parameter for predicting proarrhythmic events. As the result, close monitoring of the QT interval itself, just like INR monitoring during warfarin treatment, is mandatory both before and during treatment with these agents. [Copyright &y& Elsevier]