Active clinical trials for "Long QT Syndrome"

The human ether-a-go-go-related gene HERG (encoding Kv11.1 potassium channels) is expressed in different parts of the body including the heart, pancreas and intestines. In the heart, Kv11.1 channels play a role in ending depolarization by causing repolarization. Loss-of-function mutations of HERG cause long QT syndrome, a condition of elongated QT interval that can lead to ventricular tachycardia, syncope and sudden death. Kv11.1 channels are also found in pancreatic α- and β-cells and intestinal L-cells, where they seem to play a role in the secretion of insulin, glucagon and Glucagon-Like Peptide-1 (GLP-1). Carriers of loss-of-function mutations in the HERG gene have showed increased insulin and incretin responses after glucose ingestion and decreased fasting levels of glucagon compared to matched control persons. Blockade of Kv11.1 has shown to augment glucose dependent insulin secretion and decrease low-glucose stimulated glucagon secretion in isolated α- and β- cells. The investigators of this study hypothesize that a blockade of Kv11.1 channels will increase incretin and β cell function and decrease α cell function and thus lead to lower glucose levels in humans after glucose intake. To investigate this, The investigators of this study will perform a randomized, cross sectional study of up to 40 healthy study participants who will serve as their own controls. The study participants will undergo two 6-hours oral glucose tolerance tests, one after intake of a known Kv11.1 blocker (moxifloxacin) and one control oral glucose tolerance test after intake of placebo. Prior to both tests the study participants will wear a continuous glucose monitor and on the day of the tests they will fill out a glucose questionnaire. Investigation of the physiological role of HERG in metabolism may provide a better insight on metabolic regulation.

Patients with cardiac channelopathies needing restorative dental treatment will be included in two sessions of the study, using local dental anesthetic: lidocaine 2% with epinephrine and lidocaine 2% without vasoconstrictor. The safety of the use of two cartridges (3.6 mL) will be evaluated. The patients will be their own control and will be assessed by Holter monitoring for 28 hours, blood pressure measurement and anxiety measuring.

Since 2005, FDA has required almost all new drugs be tested for their ability to prolong the QT interval through clinical studies. This requirement stems from the increased TdP risk QT interval prolongation can cause. However, the QT interval is an imperfect biomarker, as there are multiple drugs that can prolong the QT interval, without causing increased TdP occurrence. As such, numerous drugs labeled as causing QT prolongation, may in fact have no impact on TdP occurrence. To address this problem, FDA, in collaboration with multiple external partners, has led an initiative to combine novel preclinical in vitro experiments within silico modeling and simulation followed by pharmacodynamic electrocardiographic (ECG) biomarkers. The goal is to use these novel computational and analytical tools to better predict TdP risk (beyond just the QT interval) by focusing on understanding the underlying mechanisms and applying an integrated biological systems approach. This clinical study consists of 2 parts: a 3-arm, 22-subject crossover study (Part 1) and a 4-arm, 22-subject crossover study (Part 2). These parts are included in the same protocol and study due to the similarity of the inclusion and exclusion criteria, similar procedures, and similar primary goals.

Background. In congenital long QT syndrome type 1 (LQT1), episodes of ventricular tachycardia are usually triggered by exercise and can be prevented in most patients by beta-blocker therapy. In addition, LQT1 associated with a normal resting QT interval can be unmasked by the abnormal QT response to exercise testing (failure of the QT interval to shorten normally). Preliminary data from our laboratory show that the exercise QT intervals of patients with LQT1 are partially normalized by beta-blocker therapy. It is still currently not known if beta-blockers modify the QT/heart rate relationship (a primary effect on repolarization) or if the "normalizing" effect is due to the inability of subjects on beta-blockers to attain sufficiently high workloads (due to reduced heart rate) for prolongation to occur. Moreover, the physiologic response of the exercise QT interval to beta-blockers in healthy control subjects is not known. Objective. The objective of this study is to define the impact of beta-blocker therapy on the QT response to exercise and recovery in normal subjects. Methods. Approximately 36 healthy adult subjects age-matched to previously studied LQT1 subjects will undergo 1) screening history, 2) two weeks of beta-blocker therapy ending in an exercise test, and 3) two weeks of placebo therapy ending in an exercise test. Beta blocker and placebo will be given in random order in a double-blind fashion. The QT response to exercise and recovery will be compared between drug-free and beta-blocker-treated states. These data will be compared to those previously collected for LQT1 subjects. Implications. These results will provide new information about the effect of beta-blocker therapy on repolarization parameters in normal subjects, and will provide a context in which to interpret the previous findings that beta-blocker administration modifies the QT response to exercise in LQT1 subjects.

This is a registry to examine genetic and clinical predictors of torsade de pointes events.

A double-center, randomized, double-blinded, 2-way crossover, placebo-controlled Study: Comparison of single oral dose 400mg Moxifloxacin-induced QT prolongation between healthy Chinese volunteers and Caucasian Volunteers Study Objective:Primary Objective:To compare the difference of ΔΔQTcF (Baseline-adjusted, placebo-corrected effect on QTcF) between Chinese group and Caucasian group under the same exposure (Cmax) of Moxifloxacin.Secondary Objectives:1)To compare the difference of ΔΔQTcF, heart rate, PR, RR, QRS and Moxifloxacin plasma concentration between Chinese group and Caucasian group.2)To compare slopes of Moxifloxacin plasma Concentration/QTcF value between healthy Chinese volunteers and Caucasian Volunteers.

The list of medications that prolong the QT interval and can provoke torsade de pointes keeps expanding. This list includes not only antiarrhythmic drugs, but also medications with no cardiac indications. All these medications prolong the QT interval because they block a specific potassium channel on the myocardial cell membrane: the channel for the rapid component of the delayed rectifier potassium current or "IKr". The risk for developing torsade de pointes for patients taking any of the medications with IKr blockade capabilities varies from >4% for antiarrhythmic drugs to <0.01% for non-cardiac medications. The risk depends on the strength of IKr blockade, but also on specific patient characteristics. The majority of patients who develop torsade de pointes from non-cardiac medications have identifiable risk factors. In this regard, patients with a congenital long QT syndrome are prone to develop torsade de pointes when treated with QT-prolonging medications. This is because, due to their genetically defective ion channels, patients with Long QT Syndrome (LQTS) have impaired ventricular repolarization and reduced "repolarization reserve." Therefore, it is common medical practice to strongly advise patients with congenital LQTS to avoid all medications that have IKr channel blocker capabilities. it was reported that some flavonoids contained in pink-grapefruit juice block the IKr channel. These investigators also reported that drinking 1 liter of pink-grapefruit juice causes QT prolongation in healthy volunteers. The magnitude of the QT prolongation provoked by grapefruit juice was small However, drugs causing minor QT prolongation in healthy volunteers may provoke major QT prolongation in rare or sick individuals who are then at risk for developing torsade de pointes. Consequently, one could argue that, until proven otherwise, pink-grapefruit should be added to the list of "drugs" that are forbidden for patients with LQTS

QT interval prolongation occurs in athletes and causes concerns, as it may indicate the life-threatening long QT syndrome (LQTS). Clinical and genetic testing identify those clearly affected by LQTS but in many no disease-causing mutations are found and diagnosis remains uncertain while they are barred from competitive sports. The investigators hypothesize that several cases represent an acquired form of LQTS, akin to drug-induced LQTS, caused by exercise training acting as a trigger or "second hit" on a genetic predisposition. The investigators will use next generation sequencing to screen major and minor LQTS genes plus common and rare variants modulating the QT interval in athletes with a QTc>450ms (cases) and in those with a QTc<430ms (controls). Thus, the investigators will quantify the presence of LQTS in athletes and will also focus on those who normalize their QTc after detraining, as this points to activation of stretch-receptors. The investigators will clarify QT prolongation in athletes and contribute to correct diagnosis.

In studies, the effects of drugs used for anesthesia and analgesia on QT distance were evaluated in isolation. However, drugs are administered in combination with each other during anesthesia induction. Therefore, drugs interact in terms of positive and undesirable effects. In addition, most of the studies examining anesthesia and QT distance have been conducted in non-cardiac surgery. The target group in this study is the adult patient group who will undergo cardiac surgery. The primary aim of our study is to investigate the effect of two different types of anesthesia induction techniques on QT distance in patients undergoing open-heart surgery. QT evaluation will be performed after endotracheal intubation after anesthesia induction.

In this epidemiological point prevalence study, medication profiles of patients with haloperidol treatment will be checked for drug interactions with risk of QT-prolongation. Additional clinical risk factors for developing QT-prolongation and safety measurements will be documented.