scholarly journals Towards a better understanding of QT interval variability

2011 ◽  
Vol 2 (6) ◽  
pp. 245-251 ◽  
Author(s):  
Larisa G. Tereshchenko ◽  
Ronald D. Berger
Keyword(s):  
Qt Interval ◽  
Surrogate Marker ◽  
Polymorphic Ventricular Tachycardia ◽  
Drug Induced ◽  
Technical Requirements ◽  
Qt Interval Prolongation ◽  
Torsades Des Pointes ◽  
Qt Variability ◽  
Life Threatening ◽  
Qt Interval Variability

The International Conference on Harmonization of Technical Requirements for Registration of Pharmaceuticals for Human Use (ICH) Guideline E14 recommends ‘Thorough QT Study’ as a standard assessment of drug-induced QT interval prolongation. At the same time, the value of drug-induced QTc prolongation as a surrogate marker for risk of life-threatening polymorphic ventricular tachycardia known as torsades des pointes remains controversial. Beat-to-beat variability of QT interval was recently proposed as an alternative metric. The following review addresses mechanisms of beat-to-beat QT variability, methods of QT interval variability measurements, and its prognostic value in clinical studies.

scholarly journals Safety and effectiveness of drug therapy for the acutely agitated patient (Part I)

2013 ◽  
pp. 127-136
Author(s):  
Gianluca Airoldi
Keyword(s):  
Heart Rate ◽  
Qt Interval ◽  
Physical Restraint ◽  
Safety Data ◽  
Surrogate Marker ◽  
Diagnostic Procedures ◽  
Torsades De Pointes ◽  
Long Qt ◽  
Drug Induced ◽  
Qt Interval Prolongation

Acute agitation occurs in a variety of medical and psychiatric conditions, and the management of agitated, abusive, or violent patients is a common problem in the emergency department. Rapid control of potentially dangerous behaviors by physical restraint and pharmacologic tranquillization is crucial to ensure the safety of the patient and health-care personnel and to allow diagnostic procedures and treatment of the underlying condition. The purpose of this article (the first in a 2-part series) is to review the extensive safety data published on the antipsychotic medications currently available for managing situations of this type, including older neuroleptics like haloperidol, chlorpromazine, and pimozide as well as a number of the newer atypical antipsychotics (olanzapine, risperidone, ziprasidone). Particular attention is focused on the ability of these drugs to lengthen the QT interval in surface electrocardiograms. This adverse effect is of major concern, especially in light of the reported relation between QT interval and the risk of sudden death. In patients with the congenital long-QT syndrome, a long QT interval is associated with a fatal paroxysmal ventricular arrhythmia knownas torsades de pointes. Therefore, careful evaluation of the QT-prolonging properties and arrhythmogenic potential of antipsychotic drugs is urgently needed. Clinical assessment of drug-induced QT-interval prolongation is strictly dependent on the quality of electrocardiographic data and the appropriateness of electrocardiographic analyses. Unfortunately, measurement imprecision and natural variability preclude a simple use of the actually measured QT interval as a surrogate marker of drug-induced proarrhythmia. Because the QT interval changes with heart rate, a rate-corrected QT interval (QTc) is commonly used when evaluating a drug’s effect. In clinical settings, themost widely used formulas for rate-correction are those of Bazett (QTc=QT/RR^0.5) and Fridericia (QTc=QT/RR^0.33), both of which standardize themeasuredQTinterval to an RRinterval of 1 s (heart rate of 60 bpm).However, QT variability can also be influenced by other factors that are more difficult to measure, including body fat, meals, psycho-physical distress, and circadian and seasonal fluctuations.

scholarly journals The QT long syndrome: clinical and diagnostic aspect

2021 ◽  
Vol 69 (1) ◽  
Author(s):  
Constantin Martiniuc ◽  
◽  
Serghei Pisarenco ◽  
Iurie Simionica ◽  
◽  
...  
Keyword(s):  
Qt Interval ◽  
Torsade De Pointes ◽  
Qt Prolongation ◽  
Current Data ◽  
Polymorphic Ventricular Tachycardia ◽  
Interval Prolongation ◽  
Qt Interval Prolongation ◽  
Increased Risk ◽  
Wide Range ◽  
Life Threatening

QT interval prolongation is a predictor of the life-threatening cardiac arrhythmias — polymorphic ventricular tachycardia (torsade de pointes). Long QT syndrome may be congenital or acquired. It is known that a wide range of both antiarrhythmic and non-cardiac medications might lead to QT interval prolongation. List of drugs that cause QT prolongation is constantly growing and being updated. The review contains current data on the clinical significance of the control of QT interval duration within drug therapy. Clinical conditions associated with an increased risk of QT interval prolongation are described. Drugs that can induce QT prolongation are also discussed.

scholarly journals Narrative Review: Risk-Benefit Hydroxychloroquine and Chloroquine in COVID-19

2021 ◽  
pp. 266-279
Author(s):  
Jarir At Thobari
Keyword(s):  
Qt Interval ◽  
Observational Studies ◽  
Torsade De Pointes ◽  
Conduction Block ◽  
Torsades De Pointes ◽  
Polymorphic Ventricular Tachycardia ◽  
Cardiac Events ◽  
Drug Induced ◽  
Qt Interval Prolongation ◽  
Reduction Of Mortality

Chloroquine (CQ) and Hydroxychloroquine (HCQ) are highly prescribed as medications for COVID-19 infection, although no robust or convincing data has yet been published about the efficacy in COVID-19 patients. Therefore, risk and benefit assessment are necessary for decision to prescribe these drugs in COVID-19 patient in hospitals settings. We systematically searched from MEDLINE Database which investigate the benefits and risks of HCQ and CQ among COVID-19 patients. All records were searched using the search terms Hydroxychloroquine, Chloroquine, COVID-19, and SARS-CoV-2. The selection criteria include all clinical trials and observational studies. We found 11 records about benefit and 7 records about risks on HCQ and CQ in COVID-19 patients after following inclusion and exclusion criteria. From clinical trial and observational studies have showed that HCQ is very limited benefit particularly on reduction of mortality or clinical improvement. Similarly, there were seven observational studies have estimated the cardiac event in use of HCQ or CQ in COVID-19. Even though no increase death, but these studies reported the increase risk of prolong QT-interval in high proportion and other cardiac events such as arrythmia, torsade de pointes and conduction block. We conclude that the benefit effect of HCQ and CQ in COVID-19 remains very limited. However, both medications have independently shown to increase the risk in other populations for QT-interval prolongation, drug-induced torsades de pointes/TDP (a form of polymorphic ventricular tachycardia) and drug-induced other cardiac events. 

scholarly journals Fluconazole-associated QT interval prolongation and Torsades de Pointes in a paediatric patient

2021 ◽  
pp. 1-3
Author(s):  
Ayşe Ünal Yüksekgönül ◽  
İlker Ertuğrul ◽  
Tevfik Karagöz
Keyword(s):  
Qt Interval ◽  
Torsades De Pointes ◽  
Qt Prolongation ◽  
Polymorphic Ventricular Tachycardia ◽  
Interval Prolongation ◽  
Qt Interval Prolongation ◽  
Life Threatening ◽  
Prolonged Qt Interval ◽  
Rhythm Disorder ◽  
Anti Fungal

Abstract “Torsades de pointes”, a life-threatening rhythm disorder, is a polymorphic ventricular tachycardia that usually develops in association with a prolonged QT interval. Fluconazole, an anti-fungal drug, may also induce QT prolongation, in some cases subsequent torsades de pointes. Herein, we report a 16-year-old female presenting “torsades de pointes” after administration of fluconazole and rapidly improved upon cessation of the drug.

Loperamide-induced cardiotoxicity: a case overlooked?

2021 ◽  
Vol 14 (7) ◽  
pp. e243325
Author(s):  
Sameen Iqbal ◽  
Sidra Malik Fayyaz ◽  
Yawer Saeed ◽  
Masooma Aqeel
Keyword(s):  
Qt Interval ◽  
Young Patients ◽  
Torsades De Pointes ◽  
Polymorphic Ventricular Tachycardia ◽  
Drug Induced ◽  
Over The Counter ◽  
Life Threatening ◽  
Prolonged Qt Interval ◽  
Prolonged Qt ◽  
Congenital Lqts

A young man presented to the emergency department with seizures and recurrent episodes of polymorphic ventricular tachycardia (PMVT)/torsades de pointes (TdP) requiring cardioversion and administration of intravenous magnesium. A battery of tests performed to identify a cause for his arrhythmias and seizures were all normal. A revisit of history with family revealed he had consumed over 100 tablets/day of loperamide for the past 1 year. A prolonged QT interval on his ECG raised concerns for long QT syndrome (LQTS) (congenital or acquired). Our patient was suspected to have loperamide-induced cardiotoxicity. TdP is a specific PMVT that occurs with a prolonged QT interval and is usually drug-induced. Less frequently, congenital LQTS may be implicated. With supportive care, including mechanical ventilation, vasopressors and temporary transvenous overdrive pacing, our patient recovered completely. We describe the importance of a systematic and time-sensitive approach to diagnosing critical illness. Loperamide overdose may cause QT prolongation, life-threatening arrhythmias/cardiogenic shock, or cardiac arrest. Seizures/epilepsy may also be a manifestation in young patients. There is a substantial need to revisit the safety of over-the-counter medications and increasing awareness of manifestations of drug overdose.

scholarly journals Drug-induced QT interval prolongation in cancer patients

2011 ◽  
Vol 4 (4) ◽  
pp. 223
Author(s):  
Torben K. Becker ◽  
Sai-Ching J. Yeung
Keyword(s):  
Cancer Patients ◽  
Qt Interval ◽  
Alkylating Agents ◽  
Torsade De Pointes ◽  
Interval Prolongation ◽  
Drug Induced ◽  
Vascular Disruption ◽  
Qt Interval Prolongation ◽  
Increased Risk ◽  
Multiple Drugs

Cancer patients are at an increased risk for QT interval prolongation and subsequent potentially fatal Torsade de pointes tachycardia due to the multiple drugs used for treatment of malignancies and the associated symptoms and complications. Based on a systematic review of the literature, this article analyzes the risk for prolongation of the QT interval with antineoplastic agents and commonly used concomitant drugs. This includes anthracyclines, fluorouracil, alkylating agents, and new molecularly targeted therapeutics, such as vascular disruption agents. Medications used in the supportive care can also prolong QT intervals, such as methadone, 5-HT3-antagonists and antihistamines, some antibiotics, antifungals, and antivirals. We describe the presumed mechanism of QT interval prolongation, drug-specific considerations, as well as important clinical interactions. Multiple risk factors and drug–drug interactions increase this risk for dangerous arrhythmias. We propose a systematic approach to evaluate cancer patients for the risk of QT interval prolongation and how to prevent adverse effects.

Abstract 15680: Validation of Remote Measurement of the Qtc Intervals Using an Apple Watch

Circulation ◽  
2020 ◽  
Vol 142 (Suppl_3) ◽  
Author(s):  
Carmen Spaccarotella ◽  
serena migliarino ◽  
annalisa mongiardo ◽  
Jolanda Sabatino ◽  
Giuseppe Santarpia ◽  
...  
Keyword(s):  
Qt Interval ◽  
Index Finger ◽  
Remote Measurement ◽  
Drug Induced ◽  
Left Wrist ◽  
Qt Interval Prolongation ◽  
The Right ◽  
Health Application ◽  
Pdf Format ◽  
E Mail

Introduction: In many circumstances, especially in the Covid-19 period, it could be necessary to measure the QT interval repeatedly even daily. Hypothesis: The aim of the study was to evaluate the feasibility of remote measuring LI-LII and V2 leads with using a commercially available Apple Watch Series 4. Methods: The accuracy of the QTc calculation with the smartwatch compared to the standard ECG was tested using di!erent formulae. One hundred patients admitted to our CCU were studied. LI-LII and V2 tracings were obtained immediately after the recording of the standard 12-lead ECG. The LI was recorded with the smartwatch on the left wrist and the right index finger on the crown; LII was obtained with the watch on the left lower abdomen and the right index finger on the crown; V2 lead was recorded with a smartwatch in the fourth intercostal space left parasternal with the right index finger on the crown. All recorded 30” ECGs were digitally stored using the health application of an iPhone Series 10 in the pdf format. The advantage of saving the ECG in pdf format is that it can be sent also via e-mail. Results: There was an agreement between the QTLI, QT-LII, QT-V2 and QT mean intervals of smartphone electrocardiography tracings and standard electrocardiography using Spearman’s correlation coefficient of 0.881; 0.885; 0.801; 0.911 respectively [p<0.001]. The reliability of the mean QTc measurements was tested with Bland-Altman analysis using Bazett’s, Friedericia’s, and Framingham’s formulas between standard ECG and smartwatch(Figure). Conclusions: These data demonstrated the feasibility to measure the QTc in LI, LII and V2 leads with a smartwatch with results comparable to that performed with the standard ECG. These data could have an important clinical impact both for the widespread di!usion of smartwatches and for the monitoring of drug-induced QT interval prolongation, especially in the Covid-19 era.

scholarly journals Managing drug-induced QT prolongation in clinical practice

2020 ◽  
pp. postgradmedj-2020-138661
Author(s):  
Rani Khatib ◽  
Fatima R N Sabir ◽  
Caroline Omari ◽  
Chris Pepper ◽  
Muzahir Hassan Tayebjee
Keyword(s):  
Qt Interval ◽  
Simple Algorithm ◽  
Torsades De Pointes ◽  
Daily Practice ◽  
Qt Prolongation ◽  
Key Factors ◽  
Drug Induced ◽  
Electrolyte Disturbances ◽  
Related Risk ◽  
Life Threatening

Many drug therapies are associated with prolongation of the QT interval. This may increase the risk of Torsades de Pointes (TdP), a potentially life-threatening cardiac arrhythmia. As the QT interval varies with a change in heart rate, various formulae can adjust for this, producing a ‘corrected QT’ (QTc) value. Normal QTc intervals are typically <450 ms for men and <460 ms for women. For every 10 ms increase, there is a ~5% increase in the risk of arrhythmic events. When prescribing drugs associated with QT prolongation, three key factors should be considered: patient-related risk factors (eg, female sex, age >65 years, uncorrected electrolyte disturbances); the potential risk and degree of QT prolongation associated with the proposed drug; and co-prescribed medicines that could increase the risk of QT prolongation. To support clinicians, who are likely to prescribe such medicines in their daily practice, we developed a simple algorithm to help guide clinical management in patients who are at risk of QT prolongation/TdP, those exposed to QT-prolonging medication or have QT prolongation.

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