Mechanisms, risk factors, and management of acquired long QT syndrome: a comprehensive review

Ventricular tachycardia after ketamine sedation for fracture reduction

This case report describes a 10-year-old female patient who underwent ketamine sedation for fracture reduction and experienced asymptomatic ventricular tachycardia after the sedation. She had no history of syncope, chest pain, palpations, or light-headedness and had a normal physical examination. This is the first reported case of a patient experiencing ventricular tachycardia after ketamine use for sedation. This case demonstrates a serious and potentially harmful possible adverse effect of ketamine administration.

Use of QT intervals for a more accurate diagnose of syncope and evaluation of syncope severity

BACKGROUND

This study aimed to evaluate the use of QT intervals, their diagnostic predictive value in patients with syncope and their relationship with syncope severity.

METHODS

One hundred and forty nine patients with a diagnosis of syncope were admitted to Internal Medicine departments at the University of Palermo, Italy, between 2006 and 2012, and 140 control subjects hospitalised for other causes were enrolled. QT maximum, QT minimum, QTpeak, QT corrected, QT dispersion and Tpeak-to-Tend interval were compared between two groups. The paper medical records were used for scoring with San Francisco Syncope Rule (SFSR), Evaluation of Guidelines in SYncope Study (EGSYS) score and Osservatorio Epidemiologico sulla Sincope nel Lazio (OESIL) risk score.

RESULTS

Mean QTc (p < 0.0005), mean QTmax (p < 0.0005), mean QTdisp (p < 0.0005), mean QTpeak (p = 0.005) and mean TpTe (p = 0.018) were significantly longer in patients with syncope compared with control subjects. A QTc > 424.8 ms (sensibility: 81.88 - specificity: 57.86) showed the greatest predictive value for diagnosis of syncope. On the EGSYS score and on the OESIL score, QTc was significantly prolonged in high-risk patients compared with low-risk patients. On the San Francisco Syncope Rule, QTc and QTdisp were significantly prolonged in high-risk patients compared with low-risk patients.

CONCLUSION

Mean QTc, mean QTdisp, mean TpTe, mean QTmax and mean QTpeak were significantly longer in patients with syncope compared with control subjects. Furthermore, prolonged QTc and QTdisp were associated with major severe syncope according to San Francisco Syncope Rule, EGSYS and OESIL risk scores.

Octreotide-induced long QT syndrome in a child with congenital hyperinsulinemia and a novel missense mutation (p.Met115Val) in the ABCC8 gene

BACKGROUND/AIMS

Congenital hyperinsulinism (CHI) denotes an inappropriate secretion of insulin from pancreatic β-cells in the presence of a low blood glucose level due to various genetic causes. Diazoxide is the first-line medical treatment for CHI. In case of failure, a somatostatin analogue called octreotide is used. A prolonged QT interval is an unusual side effect of octreotide which can be lethal if unrecognized.

CASE PRESENTATION

We report on a 35-day-old infant who was diagnosed with CHI on the 3rd day of his life and underwent pancreatectomy due to failure of medical treatment at 8 months. His genetic analysis revealed a compound heterozygosity for a novel missense mutation (p.Met115Val) and a nonsense mutation (p.Trp1339X) in the ABCC8 gene. Furthermore, at the 6th month of follow-up, a long QT (0.49 s) was determined by ECG examination, which was normalized following discontinuation of octreotide treatment after pancreatectomy. Thus, the long QT was considered to be secondary to octreotide medication.

CONCLUSION

We recommend ECG monitoring before and during octreotide treatment in order to recognize a prolonged QT interval and to prevent related complications in cases with congenital hyperinsulinemia.

Long QT syndrome associated with adrenal insufficiency in a patient with isolated adrenocorticotropic hormone deficiency

QT prolongation and Torsades de Pointes were observed in a 44-year-old woman who had adrenal insufficiency caused by isolated adrenocorticotropic hormone deficiency. Although she had several risk factors for QT prolongation, we concluded that the adrenal insufficiency contributed to the QT prolongation, because the electrocardiographic changes were improved after steroid replacement therapy. It is known that the QT interval in a patient with adrenal insufficiency tends to be extended. However, reports on adrenal insufficiency in which the QT interval was sufficiently prolonged to cause Torsades de Pointes are rare. Clinicians should consider the possibility of adrenal insufficiency in patients with QT prolongation.

QT Interval in Pregnant and Non-pregnant Women

INTRODUCTION

Prolongation of QT interval might result in dangerous cardiac arrhythmias, including Torsades de Pointes (TdP), consequently leading to syncope or death. A limited number of studies carried out in this respect to date have shown that QT interval might increase during pregnancy. On the other hand, it has been shown that each pregnancy might result in an increase in the risk of cardiac accidents in patients with long QT interval. Therefore, the present study was undertaken to compare QT intervals in pregnant and non-pregnant women.

METHODS

Pregnant women group consisted of 40 women in the second and third trimesters of pregnancy and the non-pregnant control group consisted of healthy women 18-35 years of age. All the patients underwent standard 12-lead electrocardiogram (ECG). The QT interval was measured for each patient at lead II. The mean corrected QT interval (QTc) and QT dispersions (QTd) were compared between the two groups.

RESULTS

Mean heart rates in the pregnant and non-pregnant groups were 98.55±14.09 and 72.53±13.17 beats/minutes (P<0.001). QTd and QTc means were in the normal range in both groups; however, these variables were 49.50±12.80 and 43.03±18.47 milliseconds in the pregnant group and 39.5±9.59 and 40.38±17.20 milliseconds in the control group, respectively (P<0.001).

CONCLUSION

The QT interval was longer in pregnant women compared to non-pregnant women; however, it was in the normal range in both groups. Therefore, it is important to monitor and manage risk factors involved in prolongation of QT interval and prevent concurrence of these factors with pregnancy.

[Improvement of medication safety by identification of genetically predisposed subjects. Personalized clinical strategies and regulatory advices]

BACKGROUND

Because adverse drug events (ADEs) have a high socio-economic impact there is an urgent need for effective prevention. In addition to process-related avoidable errors personalised approaches for the prevention of ADEs should also focus on genetic polymorphisms as potential causative agents.

AIM

Using five case reports as examples therapeutic modalities are described to illustrate the clinical impact of prospective testing aimed at estimating the individual risk of susceptible subjects.

MATERIAL AND METHODS

The role of the HLA system, the cytochrome P450 family, other metabolic enzymes and transport proteins are described to illustrate the broad range of genetic susceptibility. It is shown, why, when and for whom pretherapeutic tests on genetic polymorphisms are recommended to reduce the risk of ADEs.

RESULTS

The determination of genetic susceptibility is already implemented in clinical practice prior to (1) carbamazepine therapy in south-east Asians and (2) treatment with abacavir independent of ethnicity. Before prescribing carbamazepine or abacavir, it is recommended that therapeutic decisions be based on these test results.

CONCLUSION

The broad application of personalised medicine used as an effective tool for minimizing ADE risks is limited by the evidence-based benefit for the patient on the one hand and the costs of the test on the other hand.

Cardiovascular considerations in antidepressant therapy: an evidence-based review

There is a definite correlation between cardiovascular diseases and depressive disorders. Nevertheless, many aspects of this association have yet to be fully elucidated. Up to half of coronary artery disease patients are liable to suffer from some depressive symptoms, with approximately 20% receiving a diagnosis of major depressive disorders. Pharmacotherapy is a key factor in the management of major depression, not least in patients with chronic diseases who are likely to fail to show proper compliance and response to non-pharmacological interventions. Antidepressants are not deemed completely safe. Indeed, numerous side effects have been reported with the administration of antidepressants, among which cardiovascular adverse events are of paramount importance owing to their disabling and life-threatening nature. We aimed to re-examine some of the salient issues in antidepressant therapy vis-à-vis cardiovascular considerations, which should be taken into account when prescribing such medications.

Torsades de pointes following clarithromycin treatment

A 75-year-old woman presenting with pre-syncope, shortness of breath and nausea was admitted to the emergency department following treatment with clarithromycin. Shortly after admission she developed a prolonged QT interval leading to torsades de pointes (TdP) and cardiac arrest. She was successfully cardioverted and clarithromycin was discontinued resulting in restoration of her usual QT interval. This case is an example of acquired long QT syndrome; a disorder that can be precipitated by macrolide antibiotics such as clarithromycin. Additional risk factors present in this case include: female gender, old age, heart disease, hypokalemia and hypomagnesemia. In this manuscript we comprehensively review past cases of clarithromycin-induced long QT syndrome (LQTS) and discuss them within the context of this case.

Comparative electrocardiographic effects of intravenous ondansetron and granisetron in patients undergoing surgery for carcinoma breast: A prospective single-blind randomised trial

Background:

Postoperative nausea and vomiting (PONV) are common and distressing symptoms after surgery performed under general anaesthesia. 5-hydroxytryptamine₃ antagonists are routinely used for prevention and treatment of PONV. The aim of our study was to compare the incidence of QTc prolongation and quantify the amount of QTc prolongation with ondansetron and granisetron.

Methods:

This prospective, randomised, single-blind study was carried out in the OT and Recovery Room (RR) of a tertiary referral cancer centre. After obtaining Institutional Review Board approval and written informed consent from the patients, 70 patients undergoing elective surgery for carcinoma breast were included. In the RR, patients randomly received 8 mg of ondansetron or 1 mg of granisetron intravenously. Serial ECGs were recorded at various intervals, Non-invasive blood pressure and SpO₂ were also recorded. Chi-square test and Mann-Whiteny test were used for statistical analysis.

Results:

The demographics were similar in both groups. The incidence of significant QTc prolongation was significantly higher in the ondansetron group (22 of 37 (59.4%) vs. 11 of 33 patients (33.33%) (P<0.05)). There was an increase in the QTc interval in both the groups as compared to the baseline. The median prolongation in QTc interval from baseline was much more in the ondansetron group; this was statistically significant only at 5 and 15 min.

Conclusion:

Granisetron may be a safer option than ondanasetron for prevention and treatment of PONV due to lesser prolongation QTc interval. (ClinicalTrials.gov ID: NCT01352130)

Sudden cardiac death in young athletes: preparticipation screening for underlying cardiovascular abnormalities and approaches to prevention

The study of sudden cardiac death (SCD) in athletes has received more interest in the medical and lay press over the past few years. Professional athletes represent ideals of fitness and health, and the sudden death of prominent athletes can come as a shock. Underlying occult cardiovascular disorders are the most common cause of SCD in athletes. Unfortunately, because these disorders rarely present clinically, their initial manifestation is often a fatal event. Due to this, much attention has turned to both primary and secondary prevention. Primary prevention includes preparticipation screening and secondary prevention includes having automatic external defibrillators available at sporting events. This article summarizes the most common causes of athletic-related cardiac arrest and evaluates the screening methods used to screen for these conditions. The general sentiment is that we need to more effectively identify athletes who are at risk for SCD, but how to do so using an efficient screening system and in a cost-effective manner have not been determined.

Clinical use of antidepressant therapy and associated cardiovascular risk

A number of different psychotropic agents have been associated with an increased risk of cardiovascular disease, and these relationships have been difficult to interpret due to the presence of confounding factors. Recently, there has been renewed interest in the potential for certain antidepressants to cause QT prolongation, which is a predisposing factor for arrhythmia. However, the optimum means of determining QT remains contentious due to discrepancies between methods that may be readily applied in a clinical setting versus more detailed techniques during regulatory assessment. A number of different pharmacological mechanisms might explain the occurrence of adverse cardiac effects, and these differ according to the type of antidepressant agent. Emerging data indicate that citalopram exhibits a dose-effect relationship for QT prolongation. Whereas cardiotoxicity is readily apparent in the context of intentional antidepressant overdose, the occurrence of cardiac effects as a result of therapeutic administration is less certain. Pre-existing cardiac disease and other factors that independently predispose to arrhythmia are important considerations. Therefore, clinical judgment is needed to evaluate the overall risk or benefit of a particular antidepressant in any patient. Close monitoring should be considered for those at greatest risk of QT prolongation and arrhythmia.