Torsades de Pointes ventricular tachycardia in a pediatric patient treated with fluconazole

QTc Interval Prolongation as an Adverse Event of Azole Antifungal Drugs: Case Report and Literature Review

QTc prolongation and torsade de pointes (TdP) are significant adverse events linked to azole antifungals. Reports on QTc interval prolongation caused by these agents are limited. In this study, we report a case of a 77-year-old male with cardiovascular disease who experienced QTc prolongation and subsequent TdP while being treated with fluconazole for Candida albicans-induced knee arthritis. Additionally, a literature review was conducted on cases where QTc prolongation and TdP were triggered as adverse events of azole antifungal drugs. The case study detailed the patient's experience, whereas the literature review analyzed cases from May 1997 to February 2023, focusing on patient demographics, underlying diseases, antifungal regimens, concurrent medications, QTc changes, and outcomes. The review identified 16 cases, mainly in younger individuals (median age of 29) and women (75%). Fluconazole (63%) and voriconazole (37%) were the most common agents. Concurrent medications were present in 75% of cases, and TdP occurred in 81%. Management typically involved discontinuing or switching antifungals and correcting electrolytes, with all patients surviving. Risk assessment and concurrent medication review are essential before starting azole therapy. High-risk patients require careful electrocardiogram monitoring to prevent arrhythmias. Remote monitoring may enhance safety for patients with implanted devices. Further studies are needed to understand risk factors and management strategies.

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

"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.

Magnesium Treatment in Pediatric Patients

Pediatric patients may require magnesium replacement to treat life-threatening emergencies such as torsades de pointe or asthma exacerbations, as well as for the general replacement of magnesium in patients with hypomagnesemia. Clinicians must be aware of recommendations for magnesium administration as the route, dose, timing of administration, and formulation of magnesium can differ for each indication. It is imperative for clinicians to ensure that magnesium is appropriately administered to effectively treat the presenting indication and avoid adverse effects.

Fluconazole-induced long QT syndrome via impaired human ether-a-go-go-related gene (hERG) protein trafficking in rabbits

Aims

hERG protein trafficking deficiency has long been known in drug-induced long QT syndrome (LQTS). However, validated evidence from in vivo data kept scanty. Our goal was to investigate the proarrhythmic action of fluconazole and its underlying mechanism in an animal model.

Methods and results

Twenty female Japanese long-eared white rabbits were randomly distributed into a control group and a fluconazole group for a chronic 2-week treatment. The control group was treated with 0.5% sodium carboxymethylcellulose (CMCNa), and the fluconazole group was treated with fluconazole. Electrocardiograms (ECGs) were recorded during the experimental period. Isolated arterially perfused left ventricular wedge preparations from the rabbits were made 2 weeks after treatment, and the arrhythmia events, the transmural ECG, and action potential from both the endocardium and epicardium were recorded. The changes in hERG protein expression were measured by western blot. The fluconazole group showed a longer QT interval 1 week after treatment (P < 0.05) and a higher arrhythmia occurrence 2 weeks after treatment (P < 0.05) than the control group. The fluconazole group also showed a longer transmural dispersion of repolarization and a higher occurrence of life-threatening torsades de pointes in arterially perfused left ventricular preparations. Furthermore, western blot analysis showed that the density of mature hERG protein was lower in the fluconazole group than that in the control group.

Conclusion

Fluconazole can prolong the QT interval and possess proarrhythmic activity due to its inhibition of hERG protein trafficking in our experimental model. These findings may impact the clinical potential of fluconazole in humans.

Drug-induced proarrhythmia: risk factors and electrophysiological mechanisms

Drug-induced ventricular tachyarrhythmias can be caused by cardiovascular drugs, noncardiovascular drugs, and even nonprescription agents. They can result in arrhythmic emergencies and sudden cardiac death. If a new arrhythmia or aggravation of an existing arrhythmia develops during therapy with a drug at a concentration usually considered not to be toxic, the situation can be defined as proarrhythmia. Various cardiovascular and noncardiovascular drugs can increase the occurrence of polymorphic ventricular tachycardia of the 'torsade de pointes' type. Antiarrhythmic drugs, antimicrobial agents, and antipsychotic and antidepressant drugs are the most important groups. Age, female sex, and structural heart disease are important risk factors for the occurrence of torsade de pointes. Genetic predisposition and individual pharmacodynamic and pharmacokinetic sensitivity also have important roles in the generation of arrhythmias. An increase in spatial or temporal dispersion of repolarization and a triangular action-potential configuration have been identified as crucial predictors of proarrhythmia in experimental models. These studies emphasized that sole consideration of the QT interval is not sufficient to assess the proarrhythmic risk. In this Review, we focus on important triggers of proarrhythmia and the underlying electrophysiological mechanisms that can enhance or prevent the development of torsade de pointes.

Acquired long QT syndrome: a focus for the general pediatrician

Acquired long QT syndrome (LQTS) is a disorder of cardiac repolarization most often due to specific drugs, hypokalemia, or hypomagnesemia that may precipitate torsade de pointes and cause sudden cardiac death. Common presentations of the LQTS are palpitations, presyncope, syncope, cardiac arrest, and seizures. An abnormal 12-lead electrocardiogram obtained while the patient is at rest is the key to diagnosis. The occurrence of drug-induced LQTS is unpredictable in any given individual, but a common observation is that most patients have at least 1 identifiable risk factor in addition to drug exposure. The cornerstone of the management of acquired LQTS includes the identification and discontinuation of any precipitating drug and the correction of metabolic abnormalities, such as hypokalemia or hypomagnesemia. Most of the episodes of torsade de pointes are short-lived and terminate spontaneously. We propose a management protocol that could be useful for the daily practice in the emergency pediatric department to reduce the risk of acquired QT prolongation.

Pediatric cardiovascular safety: challenges in drug and device development and clinical application

Development of pediatric medications and devices is complicated by differences in pediatric physiology and pathophysiology (both compared with adults and within the pediatric age range), small patient populations, and practical and ethical challenges to designing clinical trials. This article summarizes the discussions that occurred at a Cardiac Safety Research Consortium-sponsored Think Tank convened on December 10, 2010, where members from academia, industry, and regulatory agencies discussed important issues regarding pediatric cardiovascular safety of medications and cardiovascular devices. Pediatric drug and device development may use adult data but often requires additional preclinical and clinical testing to characterize effects on cardiac function and development. Challenges in preclinical trials include identifying appropriate animal models, clinically relevant efficacy end points, and methods to monitor cardiovascular safety. Pediatric clinical trials have different ethical concerns from adult trials, including consideration of the subjects' families. Clinical trial design in pediatrics should assess risks and benefits as well as incorporate input from families. Postmarketing surveillance, mandated by federal law, plays an important role in both drug and device safety assessment and becomes crucial in the pediatric population because of the limitations of premarketing pediatric studies. Solutions for this wide array of issues will require collaboration between academia, industry, and government as well as creativity in pediatric study design. Formation of various epidemiologic tools including registries to describe outcomes of pediatric cardiac disease and its treatment as well as cardiac effects of noncardiovascular medications, should inform preclinical and clinical development and improve benefit-risk assessments for the patients. The discussions in this article summarize areas of emerging consensus and other areas in which consensus remains elusive and provide suggestions for additional research to further our knowledge and understanding of this topic.

Fluconazole inhibits hERG K(+) channel by direct block and disruption of protein trafficking

Fluconazole, a commonly used azole antifungal drug, can induce QT prolongation, which may lead to Torsades de Pointes and sudden death. To investigate the arrhythmogenic side effects of fluconazole, we studied the effect of fluconazole on human ether-a-go-go-related gene (hERG) K(+) channels (wild type, Y652A and F656C) expressed in human embryonic kidney (HEK293) cells using a whole-cell patch clamp technique, Western blot analysis and confocal microscopy. Fluconazole inhibited wild type hERG currents in a concentration-dependent manner, with a half-maximum block concentration (IC(50)) of 48.2±9.4μM. Fluconazole did not change other channel kinetics (activation and steady-state inactivation) of hERG channel. Mutations in drug- binding sites (Y652A or F656C) of the hERG channel significantly attenuated the hERG current blockade by fluconazole. In addition, fluconazole inhibited the trafficking of hERG protein by Western blot analysis and confocal microscopy, respectively. These findings indicate that fluconazole may cause acquired long QT syndrome (LQTS) via a direct inhibition of hERG current and by disrupting hERG protein trafficking, and the mutations Y652 and F656 may be obligatory determinants in inhibition of hERG current for fluconazole.

Invasive fungal infections in the ICU

Invasive fungal infections are major causes of morbidity and mortality in critically ill patients. Foremost among these is invasive candidiasis. In recent years, invasive aspergillosis (IA) and zygomycosis have emerged as major problems in susceptible, critically ill patients. Risk factors for invasive fungal infections, including disrupted anatomic barriers, suppressed antifungal host responses, and exposure to potentially opportunistic fungi are common in critically ill patients. The expanded antifungal armamentarium and advent of rapid diagnostic techniques are altering the approach to invasive fungal infections in the intensive care unit (ICU). Herein, we review recent developments in the field of antifungal host defenses, the changing epidemiology of fungal infections in the ICU, the pharmacology of antifungal agents of importance to critically ill patients, and the evolving approaches to therapy in this setting.