Long QT syndrome: diagnosis and management

Single intravenous dose ondansetron induces QT prolongation in adult emergency department patients: a prospective observational study

BACKGROUND

Ondansetron is one of the most commonly used drugs in the emergency department (ED) for treating nausea and vomiting, particularly in intravenous (IV) form. Nevertheless, it has been shown to prolong QT interval and increase the risk of ventricular dysrhythmias. This study evaluated the associations between single IV ondansetron dosage and subsequent QTc prolongation in the ED.

METHODS

In this prospective observational study, a total number of 106 patients presenting to the ED in a 3-month period with nausea and vomiting treated with IV ondansetron were enrolled. QT and QTc intervals were measured at baseline (QT0 and QTc0), and 60 min (QT60 and QTc60) following a single-dose administration of ondansetron at 4 or 8 mg doses. To evaluate the predictive ability of these variables, we employed receiver operating characteristic (ROC) curve analyses.

RESULTS

The predictive models for QTc prolongation 1-hour post-ondansetron administration showed the following: at baseline, the area under curve of 0.70 for QT, 0.71 for QTc, and 0.64 for dosage. Conversely, a QTc0 = 375 msec indicated a QTc60 > 480 msec with a specificity of 97%. Additionally, a QTc0 of 400 msec had a sensitivity of 100% in predicting a QTc60 < 480 msec, while a QTc0 > 460 msec predicted a QTc60 > 480 msec with a specificity of 98%. Moreover, 8 mg doses were associated with higher rates of QTc60 prolongation, while 4 mg doses favored maintaining QTc60 within normal limits.

CONCLUSIONS

Our study demonstrates the predictive capacity of QT0, QTc0, and ondansetron dosage in forecasting QTc60 prolongation (> 480 msec) post-ondansetron administration. These findings advocate for their incorporation into clinical protocols to enhance safety monitoring in adult ED patients.

Effect on QTc interval by switching from methadone to equipotent R-methadone dose in methadone maintenance treatment patients

Methadone (R,S-methadone) can prolong the QT interval. R-methadone inhibits cardiac potassium channel function less than S-methadone. We tested if switching from methadone to R-methadone would reduce corrected QT (QTc) intervals in methadone maintenance treatment (MMT) patients. Nine patients, with automatically read QTc intervals ≥450 ms, were required to detect a 20 ms (clinically relevant) reduction in QTc intervals with 15 ms standard deviation (SD) and 90% power. Nine stabilized MMT patients, using median (range) 70 (40-120) mg methadone, were included. Data (ECG recordings, serum samples, and withdrawal symptoms) were collected both before drug intake (Cmin ) and at 3 h after drug intake (Cmax ), and were collected on the day before the switch from methadone to equipotent R-methadone dose and at 14 and 28 days after the switch. A cardiologist calculated QTc intervals retrospectively. Serum electrolytes and methadone concentrations were measured. Mean QTc intervals at Cmin were 472 ms and 422 ms on methadone (automatically and manually read) and 414 ms on R-methadone (manually read). Mean (SD) change in QTc intervals was -8 (10) ms (p = 0.047) at Cmin but non-significant at Cmax . R-methadone showed a concentration-dependent relationship with QTc intervals. Switching to R-methadone reduced QTc intervals, but far less than the 20 ms considered clinically relevant.

High-dose benzodiazepine use and QTc interval prolongation, a latent class analysis study

Benzodiazepine (BDZ) addiction is a widespread and multifaceted phenomenon. For many patients, especially females, the concomitant use of other drugs also increases their risk of QTc prolongation, possibly leading to complications such as seizures and even sudden death. However, the relationship between BDZ use and QTc prolongation is currently unclear. The present study aims to examine patterns of polysubstance use among a sample of Italian adults with BDZ dependence in relation with their QTc prolongation risk. We used Latent Class Analysis (LCA) on data collected from 251 inpatients of the Addiction Medicine Unit in Verona to group patients into three classes according to their substance use and their QTc prolongation risk. Results showed no significant relationship between QTc prolongation and BDZ use in any of the classes considered. We conclude that BDZs, even if used long-term and at high dosages, can be considered safe in terms of cardiovascular complications for patients.

Pathophysiology and treatment of adults with arrhythmias in the emergency department, part 2: Ventricular and bradyarrhythmias

PURPOSE

This is the second article in a 2-part series reviewing the pathophysiology and treatment considerations for arrhythmias. Part 1 of the series discussed aspects related to treating atrial arrhythmias. Here in part 2, the pathophysiology of ventricular arrhythmias and bradyarrhythmias and current evidence on treatment approaches are reviewed.

SUMMARY

Ventricular arrhythmias can arise suddenly and are a common cause of sudden cardiac death. Several antiarrhythmics may be effective in management of ventricular arrhythmias, but there is robust evidence to support the use of only a few of these agents, and such evidence was largely derived from trials involving patients with out-of-hospital cardiac arrest. Bradyarrhythmias range from asymptomatic mild prolongation of nodal conduction to severe conduction delays and impending cardiac arrest. Vasopressors, chronotropes, and pacing strategies require careful attention and titration to minimize adverse effects and patient harm.

CONCLUSION

Ventricular arrhythmias and bradyarrhythmias can be consequential and require acute intervention. As experts in pharmacotherapy, acute care pharmacists can participate in providing high-level intervention by aiding in diagnostic workup and medication selection.

Acquired Long QT Syndrome: Ventricular Fibrillation in an Otherwise Healthy Young Female

Long QT syndrome (LQTS) occurs when there is an abnormality of myocardial repolarization characterized specifically by a prolonged QT interval on an electrocardiogram (ECG). This can be particularly dangerous as it is associated with an increased risk of polymorphic ventricular tachycardia and a life-threatening arrhythmia otherwise known as torsades de pointes (TdP). We present a case of a 40-year-old Indian female whose medical history was significant only for anemia and depression/anxiety that presented in a ventricular fibrillation cardiac arrest after becoming dyspneic and light-headed while dancing. Of relevance, she was taking sertraline 50mg once daily, a class of medications known to prolong the QT interval as well as having low serum calcium on presentation. Both her initial and subsequent electrocardiograms illuminated significantly prolonged QTc intervals. She subsequently sustained a ventricular tachycardia cardiac arrest, which degenerated into ventricular fibrillation in the cardiac intensive care unit two days later. Ultimately, the patient was pronounced brain-dead by the end of the week. We concluded this to be a case of LQTS predisposing to TdP, which then would degenerate into ventricular fibrillation. This case highlights multiple risk factors that are known to predispose to the aforementioned etiology. Further research is needed not only on common medications and their dose-dependent relationship on the QT interval across different ethnic groups but also on educating providers regarding multiple risk factors they may or may not have the power to control.

Clinical and electrocardiogram presentations of patients with high serum potassium concentrations within emergency settings: a prospective study

BACKGROUND

Elevated potassium level is a common and reversible peri-arrest condition. Diagnosis and management of hyperkalemia in a short time is critical, where electrocardiogram (ECG) alterations might be helpful. We aimed to investigate the role of clinical features and ECGs in early diagnosing and treating hyperkalemia.

METHODS

Prospectively, adult patients who presented to the emergency department (ED) from July 2019 to March 2020 with hyperkalemia (serum potassium ≥5.5mmol/L) were included. History was obtained, and laboratory investigations and ECGs were performed at the presentation and before initiating hyperkalemia therapy. Hyperkalemia severity was divided into mild (5.5-5.9mmol/L), moderate (6.0-6.4mmol/L), and severe (≥6.5mmol/L). A cardiologist and emergency physician blinded to laboratory values, study design, and patients' diagnoses interpreted ECGs and presenting symptoms independently to predict hyperkalemia.

RESULTS

Sixty-seven hyperkalemic patients with a mean (±SD) serum potassium level of 6.5±0.7mmol/L were included in this study. The mean age was 63.9±15.1, and 58.2% were females. Hyperkalemia was mild in 10.4%, moderate in 40.3%, and severe in 49.3%. Almost two thirds of patients (71.6%) had hypertension, 67.2% diabetes, and 64.2% chronic kidney disease. About one-quarter of patients (22.4%) were asymptomatic, while fatigue (46.3%), dyspnea (28.4%), and nausea/vomiting (20.9%) were the most common presenting symptoms. Normal ECGs were observed in 25.4% of patients, while alterations in 74.6%. Atrial fibrillation (13.4%), peaked T wave (11.9%), widened QRS (11.9%), prolonged PR interval (10.5%), and flattening P wave (10.5%) were the most common. Peaked T wave was significantly more common in severe hyperkalemia (87.5%) than in mild and moderate hyperkalemia (12.5%, 0.0%, respectively) (p=0.041). The physicians' sensitivities for predicting hyperkalemia were 35.8% and 28.4%, improved to 51.5% and 42.4%, respectively, when limiting the analyses to severe hyperkalemia. The mean (±SD) time to initial hyperkalemia treatment was 63.8±31.5 min. Potassium levels were positively correlated with PR interval (r=0.283, p=0.038), QRS duration (r=0.361, p=0.003), peaked T wave (r=0.242, p=0.041), and serum levels of creatinine (r=0.347, p=0.004), BUN (r=0.312, p=0.008), and CK (r=0.373, p=0.039).

CONCLUSIONS

The physicians' abilities to predict hyperkalemia based on ECG and symptoms were poor. ECG could not be solely relied on, and serum potassium tests should be conducted for accurate diagnosis.

Vandetanib-Induced Hyponatremia and Torsades De Pointes: A Case Report

Medullary thyroid cancer (MTC) is a neuroendocrine tumor of the parafollicular cells of the thyroid gland. The prognosis is very poor in patients with advanced MTC. Vandetanib was approved for advanced MTC after randomized control trials showed that it had therapeutic efficacy and considerably prolonged progression-free survival. Vandetanib therapy is associated with serious cardiovascular side effects including hypertensive crisis and arrhythmias due to prolonged QTc. We present a case of an 83-year-old female with advanced metastatic MTC who is under treatment with vandetanib 300 mg/day and developed medication-related hyponatremia, QTc prolongation, ventricular fibrillation (VF), and torsades de pointes (TdP). Her vandetanib therapy was held. Subsequently, she did not show recurrences of TdP. This is the second such case report in the literature.

Case Report: High doses of Zolpidem and QT interval lengthening: Is there a relationship? A case series

Zolpidem is indicated in cases of severe insomnia in adults and, as for BDZs, its assumption should be limited to short periods under close medical supervision. Since several drugs cause corrected QT interval (QTc) elongation, the authors investigated whether high daily doses of Zolpidem could cause QTc elongation. The study was conducted in the Addiction Medicine Unit of the G.B. Rossi University Hospital in Verona. The data were collected from hospitalizations carried out between January 2015 and February 2020 and refer to a total of 74 patients, 38 males and 36 females, who were treated for detoxification from high doses of Zolpidem with the "Verona Detox Approach With Flumazenil." One patient out of 74 had QTc elongation (479 ms). The patient was male and took a daily dose of 50 mg of Zolpidem; he did not take concomitant therapies that could cause QTc lengthening. He had no electrolyte alterations, no contemporary or previous intake of barbiturates, heroin, cocaine, THC, alcohol, NMDA or nicotine which could cause an elongation of the QTc interval. The present study highlights the low risk of QTc elongation due to high dosages of Zolpidem; however, if, on one hand, we can affirm that Zolpidem is a safe drug, on the other, the widespread use of high dosages of this drug for prolonged periods of time is problematic and worrying.

Refractory Torsades de Pointes Due to Dofetilide Overdose

Dofetilide, a class III antiarrhythmic, is widely used in the treatment of cardiac arrhythmias. Antiarrhythmic drugs can have a long duration of action that prolongs the QT interval. This causes bradycardia that predisposes to R-on-T phenomenon subsequently leading to torsades de pointes (TdP). This necessitates constant monitoring to prevent or treat ventricular arrhythmias or bradycardia associated with cardiac medications. Although extremely rare, dofetilide overdose has been described in the literature. However, no evidence found in the current literature required prolonged intervention after the initial acute stabilization, leading to scarcity of data for treatment of ongoing dofetilide overdose. We present the case of an intentional dofetilide overdose in a 61-year-old Caucasian woman with a history of congestive heart failure, atrial fibrillation, stage IIIb chronic kidney disease, diabetes mellitus type II, hypothyroidism, morbid obesity, and hypertension that required extensive interventions for refractory TdP that lasted 4 days. Therapeutic as well as excess dosage of dofetilide can lead to TdP, which is usually controlled by decreasing the dose or terminating drug administration. If the arrhythmia is not resolved, guidelines recommend management with activated charcoal if ingestion is within 15 minutes, followed by administration of 2 g IV (intravenous) magnesium and addressing the electrolyte imbalance. However, if the arrhythmia is persistent due to ongoing dofetilide toxicity, isoproterenol is given as a bridge to overdrive pacing and dopamine is used as an alternative to isoproterenol.

Temporary atrial overdrive pacing during a drug-refractory electrical storm in acute myocardial infarction

A 64-year-old man with diabetes mellitus was diagnosed with a non-ST-segment elevation myocardial infarction and was treated with stent implantation. Four days later, he developed an electrical storm (ES) that persisted despite antiarrhythmic drugs and sedation. External defibrillation was performed more than 100 times over 2 hours. After ruling out the common causes of polymorphic ventricular tachycardia, an ES was considered because of brady-dependent R-on-T phenomenon, presumably precipitated by antiarrhythmic drugs. Temporary transvenous atrial overdrive pacing allowed complete suppression of premature ventricular complexes and ventricular fibrillation.

Effects of long-term fasting and confinement on the cardiovascular activity

Fasting has been demonstrated to improve health and slow aging in human and other species; however, its impact on the human body in the confined environment is still unclear. This work studies the effects of long-term fasting and confined environment on the cardiovascular activities of human via a 10-day fasting experiment with two groups of subjects being in confined (6 subjects) and unconfined (7 subjects) environments respectively and undergoing the same four-stage fasting/feeding process. It is found that the confinement has significant influences on the autonomic regulation to the heart rate during the fasting process by altering the activity of the parasympathetic nervous system, which is manifested by the significant higher pNN50, rMSSD, and Ln-HF of heart rate variability (HRV) (p < 0.05) and slower heart rate (p < 0.01) in the confined group than that in the unconfined group. Furthermore, the long-term fasting induces a series of changes in both groups, including reduced level of serum sodium (p < 0.01), increased the serum calcium (p < 0.05), prolonged QTc intervals (p < 0.05), and reduced systolic blood pressures (p < 0.05). These effects are potentially negative to human health and therefore need to be treated with caution. Study of the effects of fasting and confinement on the cardiovascular activities.

QT interval prolongation and the risk of malignant ventricular dysrhythmia and/or cardiac arrest: Systematic search and narrative review of risk related to the magnitude of QT interval length

Prolongation of the QTc interval is associated with an increased risk of malignant ventricular dysrhythmias, such as ventricular tachycardia (VT), and sudden cardiac death. The quantifiable risk rates of adverse dysrhythmic outcome in relation to specific QTc interval length are not known. We conducted a literature review on the topic of QT interval prolongation in adult patients and the associated risk of malignant dysrhythmic event. We specifically formulated our literature search and subsequent literature review to address the following question: Can the clinician identify specific QTc intervals at which a specific quantifiable risk of malignant dysrhythmic event (malignant ventricular dysrhythmia and/or cardiac arrest) occurs in an undifferentiated adult patient population? In the literature search, we identified 701 studies; upon review using specific, pre-determined inclusion criteria, we identified 16 articles for inclusion in the review. From this literature, we were unable to answer the question in a quantifiable manner and only noted that the risk of malignant dysrhythmic event increases with progressively longer QTc interval. The current literature on this topic is inadequate to answer this important question due to heterogenous study methodology, patient populations, endpoints, and periods of observation. Additional prospective research is required on this topic, aimed at addressing the important issue of specific, quantifiable risk and its relation to degree of prolongation of the QTc interval.

QT interval prolongation and the rate of malignant ventricular dysrhythmia and cardiac arrest in adult poisoned patients

INTRODUCTION

Prolongation of QTc interval, a common electrocardiographic (ECG) abnormality encountered in the toxicology patient, is reportedly associated with an increased risk of malignant ventricular dysrhythmias (MVD), such as ventricular tachycardia (VT, with and without a pulse), ventricular fibrillation (VF), and/or cardiac arrest. Quantifiable cardiac arrest risk in relation to specific QTc interval length is not known in this population.

METHODS

We conducted a retrospective, observational study to assess the rate of cardiac arrest and its association with degree of QTc prolongation in a cohort of patients requiring toxicology consultation.

RESULTS

550 patients were included in our analysis (average age 36 years and 49% male). Average QTc was 453 milliseconds (ms). Overall incidence of cardiac arrest in the study cohort was 1.1% with 6 reported cases; when considering patients with QTc > 500 ms, incidence was 1.7%. Two patients with cardiac arrest experienced ventricular dysrhythmia with decompensation prior to cardiac arrest; four patients developed sudden cardiac arrest.

CONCLUSIONS

The risk of malignant ventricular dysrhythmia, including cardiac arrest, is low in this poisoned patient population with an overall rate of 1.1%. Two-thirds of cardiac arrest cases occurred in patients with normal QTc intervals. When considering patients with prolonged QTc intervals, the rate of cardiac arrest remains very low at 0.8%. Considering QTc greater than 500 ms, the rate of cardiac arrest is 1.7%. Further prospective studies are required to quantify the risk of malignant ventricular dysrhythmias, including cardiac arrest, and its relation to the degree of QTc interval in poisoned patients.

[CME ECC 66: Torsade de Pointes: The Danger of a Rotating Heart Axis]

CME ECC 66: Torsade de Pointes: The Danger of a Rotating Heart Axis Abstract. Torsade de pointes tachycardia is a potentially life-threatening heart rhythm disorder, caused by prolongation of the QT-interval resulting in triggered activity. This QT-prolongation can be congenital or acquired. If acquired, it is mainly caused by pharmacological therapy. The hallmark of torsade de pointes is an undulating QRS axis with a twist of the QRS complex around the ECG's baseline. Often, this polymorphic ventricular tachycardia is self-limiting, but degeneration into ventricular fibrillation is possible, which makes torsade de pointes tachycardia dangerous. This article aims to provide insights into etiology, diagnostics, prevention and management of this heart rhythm disorder.

Approach to Ventricular Arrhythmias in the Intensive Care Unit

Arrhythmias are commonly encountered in the intensive care unit as a primary admitting diagnosis or secondary to an acute illness. Appropriate identification and treatment of ventricular arrhythmias in this setting are particularly important to reduce morbidity and mortality. This review highlights the epidemiology, mechanisms, electrocardiographic features, and treatment of ventricular arrhythmias.

A Unique Interplay of Multiple Predisposing Factors Culminating in a Catastrophic QT Prolongation

Implantable cardioverter-defibrillators (ICDs) are used in patients without a reversible cause for long QT syndrome (LQTS) and secondary prevention in patients with LQTS-associated sudden cardiac arrest. We present a female patient with multiple reversible factors for QT prolongation, including the use of antidepressants, antidiarrheals, antiemetics, and antihistamines; chronic malabsorption from bariatric surgery; probable Gitelman syndrome and urinary losses of electrolytes, causing QT prolongation which leads to polymorphic ventricular tachycardia and a successfully resuscitated cardiac arrest. Our patient also had history suggestive of probable congenital LQTS with multiple childhood syncopal episodes and a history of seizures in first-degree relatives, further justifying the placement of an ICD. Also, this case gives us an opportunity to delve into the risks of catastrophic QT prolongation in the morbidly obese population undergoing bariatric surgery.

ECG alterations suggestive of hyperkalemia in normokalemic versus hyperkalemic patients

Background

In periarrest situations and during resuscitation it is essential to rule out reversible causes. Hyperkalemia is one of the most common, reversible causes of periarrest situations. Typical electrocardiogram (ECG) alterations may indicate hyperkalemia. The aim of our study was to compare the prevalence of ECG alterations suggestive of hyperkalemia in normokalemic and hyperkalemic patients.

Methods

170 patients with normal potassium (K⁺) levels and 135 patients with moderate (serum K⁺ = 6.0–7.0 mmol/l) or severe (K⁺ > 7.0 mmol/l) hyperkalemia, admitted to the Department of Emergency Medicine at the Somogy County Kaposi Mór General Hospital, were selected for this retrospective, cross-sectional study. ECG obtained upon admission were analyzed by two emergency physicians, independently, blinded to the objectives of the study. Statistical analysis was performed using SPSS22 software. χ² test and Fischer exact tests were applied.

Results

24% of normokalemic patients and 46% of patients with elevated potassium levels had some kind of ECG alteration suggestive of hyperkalemia. Wide QRS (31.6%), peaked T-waves (18.4%), Ist degree AV-block (18.4%) and bradycardia (18.4%) were the most common and significantly more frequent ECG alterations suggestive of hyperkalemia in severely hyperkalemic patients compared with normokalemic patients (8.2, 4.7, 7.1 and 6.5%, respectively). There was no significant difference between the frequency of ECG alterations suggestive of hyperkalemia in normokalemic and moderately hyperkalemic patients. Upon examining ECG alterations not typically associated with hyperkalemia, we found that prolonged QTc was the only ECG alteration which was significantly more prevalent in both patients with moderate (17.5%) and severe hyperkalemia (21.1%) compared to patients with normokalemia (5.3%).

Conclusions

A minority of patients with normal potassium levels may also exhibit ECG alterations considered to be suggestive of hyperkalemia, while more than half of the patients with hyperkalemia do not have ECG alterations suggesting hyperkalemia. These results imply that treatment of hyperkalemia in the prehospital setting should be initiated with caution. Multiple ECG alterations, however, should draw attention to potentially life threatening conditions.

Pharmacologic Treatment of Opioid Use Disorder: a Review of Pharmacotherapy, Adjuncts, and Toxicity

Opioid use disorder continues to be a significant source of morbidity and mortality in the USA and the world. Pharmacologic treatment with methadone and buprenorphine has been shown to be effective at retaining people in treatment programs, decreasing illicit opioid use, decreasing rates of hepatitis B, and reducing all cause and overdose mortality. Unfortunately, barriers exist in accessing these lifesaving medications: users wishing to start buprenorphine therapy require a waivered provider to prescribe the medication, while some states have no methadone clinics. As such, users looking to wean themselves from opioids or treat their opioid dependence will turn to alternative agents. These agents include using prescription medications, like clonidine or gabapentin, off-label, or over the counter drugs, like loperamide, in supratherapeutic doses. This review provides information on the pharmacology and the toxic effects of pharmacologic agents that are used to treat opioid use disorder. The xenobiotics reviewed in depth include buprenorphine, clonidine, kratom, loperamide, and methadone, with additional information provided on lofexidine, akuamma seeds, kava, and gabapentin.

Prevalence and prognostic significance of prolonged QTc interval in emergency medical patients: A prospective observational study

Introduction:

QTc interval is affected by many factors and prolongation of same may have prognostic significance. A significant number of patients admitted in medical emergency are acutely ill, have multiple comorbidities and are on medications, all of these factors might affect QTc interval and prognosis.

Materials and Methods:

Single-center, prospective, observational study was carried out on 279 patients of different illnesses recruited from emergency medical services attached to the Department of Internal Medicine at Postgraduate Institute of Medical Education and Research, Chandigarh, India, a tertiary care hospital.

Results:

Out of 279 patients, 95 were found to have prolonged QTc interval with the prevalence of 34.1%. Fifteen patients (5.4%) had markedly prolonged QTc interval (QTc >500 ms). Of various medical conditions, we found statistically significantly higher number of patients of chronic kidney disease (P = 0.047), chronic liver disease (P < 0.001), hemorrhagic cerebrovascular accident (P = 0.026), and heart failure (P = 0.009) with prolonged QTc interval. Among laboratory abnormalities, patients with low hemoglobin (P = 0.032), with deranged renal functions (P = 0.033), and with hypokalemia (P = 0.026) had a greater share of patients with prolonged QTc interval. There was no difference in duration of hospital stay and frequency of hospital mortality between two groups, although, on subgroup analysis, patients with markedly prolonged QTc interval had significantly higher hospital mortality (P = 0.029). The frequency of ventricular tachycardia was also significantly higher in patients with prolonged QTc interval (P = 0.008).

Conclusion:

High prevalence of prolonged QTc interval was found in Indian emergency medical patients. There was no difference in hospital mortality though on subgroup analysis, patients with markedly prolonged QTc interval had significantly more episodes of in-hospital ventricular tachycardia and hospital mortality.

Prevalence of the risk factors for QT prolongation and associated drug-drug interactions in a cohort of medical inpatients

BACKGROUND/PURPOSE

Medical inpatients are at increased risk of QT interval prolongation due to multiple risk actors and QT prolonging drugs. This study aimed to identify the prevalence of risk factors for QT prolongation; QT prolonging medications; associated drug-drug interactions (QT-DDIs); their predictors; and TdP (torsades de pointes) risks of drugs.

METHODS

This cohort study was carried out in medical wards of two tertiary hospitals in Khyber Pakhtunkhwa, Pakistan. The QT-DDIs were identified using Micromedex DrugReax® and AZCERT (Arizona Center for Education and Research on Therapeutics) QT drugs lists. AZCERT QT drugs lists were used to identify TdP risks. Logistic regression analysis was performed to identify predictors of QT-DDIs.

RESULTS

Total 400 patients were included in this study. The most frequent QT prolonging risk factors included use of ≥1 QT prolonging drugs (74.5%), female gender (55%) and diabetes mellitus (36.3%). Total 487 QT prolonging drugs were identified. According to AZCERT classification, 33.8% of the interacting drugs were included in list-1 (known risk of TdP), 0.9% in list-2 (possible risk of TdP) and 58.8% in list-3 (conditional risk of TdP). The occurrence of QT-DDIs was significantly associated with ≥10 prescribed medications (p = 0.01), chronic liver disease (p = 0.05), chronic obstructive pulmonary disease (p = 0.03), gastroenteritis (p = 0.02), antimicrobials (p < 0.001), antiemetics (p < 0.001) and antinausea (p < 0.001).

CONCLUSION

A substantial number of patients were exposed to risk factors for QT prolongation; and QT prolonging drugs such as proton pump inhibitors, antimicrobials and diuretics which may lead to serious outcomes.

Incidence, Diagnosis, and Management of QT Prolongation Induced by Cancer Therapies: A Systematic Review

Background

The cardiovascular complications of cancer therapeutics are the focus of the burgeoning field of cardio‐oncology. A common challenge in this field is the impact of cancer drugs on cardiac repolarization (ie, QT prolongation) and the potential risk for the life‐threatening arrhythmia torsades de pointes. Although QT prolongation is not a perfect marker of arrhythmia risk, this has become a primary safety metric among oncologists. Cardiologists caring for patients receiving cancer treatment should become familiar with the drugs associated with QT prolongation, its incidence, and appropriate management strategies to provide meaningful consultation in this complex clinical scenario.

Methods and Results

In this article, we performed a systematic review (using Preferred Reporting Items of Systematic Reviews and Meta‐Analyses (PRISMA) guidelines) of commonly used cancer drugs to determine the incidence of QT prolongation and clinically relevant arrhythmias. We calculated summary estimates of the incidence of all and clinically relevant QT prolongation as well as arrhythmias and sudden cardiac death. We then describe strategies to prevent, identify, and manage QT prolongation in patients receiving cancer therapy. We identified a total of 173 relevant publications. The weighted incidence of any corrected QT (QTc) prolongation in our systematic review in patients treated with conventional therapies (eg, anthracyclines) ranged from 0% to 22%, although QTc >500 ms, arrhythmias, or sudden cardiac death was extremely rare. The risk of QTc prolongation with targeted therapies (eg, small molecular tyrosine kinase inhibitors) ranged between 0% and 22.7% with severe prolongation (QTc >500 ms) reported in 0% to 5.2% of the patients. Arrhythmias and sudden cardiac death were rare.

Conclusions

Our systematic review demonstrates that there is variability in the incidence of QTc prolongation of various cancer drugs; however, the clinical consequence, as defined by arrhythmias or sudden cardiac death, remains rare.

Torsade de Pointes Induced by Hypokalemia from Imipenem and Piperacillin

Imipenem-cilastatin and piperacillin-tazobactam are two antibiotics with broad antimicrobial coverage. Besides the many well established adverse effects of these drugs, there have been few case reports of hypokalemia. Here we present an interesting case of resistant hypokalemia caused by these drugs leading to Torsades de Pointes which has never been reported in the past. Hypokalemia resolved with discontinuation of piperacillin.

Prevalence of resting-ECG abnormalities in systemic lupus erythematosus: a single-center experience

Cardiovascular complications are a major cause of morbidity and even mortality among systemic lupus erythematosus (SLE) patients. Whether cardiac arrhythmias contribute to this burden among SLE patients, however, is not currently known. The goal of this study was to determine the prevalence of cardiac conduction abnormalities among SLE patients from a single center. We retrospectively reviewed the medical records of SLE patients who had 12-lead electrocardiograms (ECGs) available from various settings at a single academic center over the period of 10 years. In addition, ICD-9 codes for arrhythmias were obtained for the SLE patients whose ECGs were reviewed. The hospital setting (in-patient, out-patient, emergency department) and the indication for obtaining the ECG were evaluated. Two hundred thirty-five SLE patients had available ECGs. Sinus tachycardia was most common (18%). With direct ECG review, tachyarrhythmias were found in 6% of SLE patients, with the most common being atrial fibrillation (3%). Atrial fibrillation was seen even more frequently (9%) when ICD-9 codes were reviewed. No patients had brady-arrhythmias. QT prolongation was present in 17% of patients upon direct ECG review. More ECGs with tachyarrhythmias and QT prolongation were found among inpatients, with preoperative evaluation and gastrointestinal symptoms being the most common indications. Sinus tachycardia was the most common finding seen among our SLE patients with ECGs. Further study into the possible mechanisms behind this is warranted, including the possibility of autonomic nervous system involvement in SLE.

Drug-induced Inhibition and Trafficking Disruption of ion Channels: Pathogenesis of QT Abnormalities and Drug-induced Fatal Arrhythmias

Risk of severe and fatal ventricular arrhythmias, presenting as Torsade de Pointes (TdP), is increased in congenital and acquired forms of long QT syndromes (LQTS). Drug-induced inhibition of K+ currents, IKs, IKr, IK1, and/or Ito, delay repolarization, prolong QT, and increase the risk of TdP. Drug-induced interference with IKr is the most common cause of acquired LQTS/TdP. Multiple drugs bind to KNCH2-hERG-K+ channels affecting IKr, including antiarrythmics, antibiotics, antivirals, azole-antifungals, antimalarials, anticancer, antiemetics, prokinetics, antipsychotics, and antidepressants. Azithromycin has been recently added to this list. In addition to direct channel inhibition, some drugs interfere with the traffic of channels from the endoplasmic reticulum to the cell membrane, decreasing mature channel membrane density; e.g., pentamidine, geldalamicin, arsenic trioxide, digoxin, and probucol. Other drugs, such as ketoconazole, fluoxetine, norfluoxetine, citalopram, escitalopram, donepezil, tamoxifen, endoxifen, atazanavir, and roxitromycin, induce both direct channel inhibition and impaired channel trafficking. Although many drugs prolong the QT interval, TdP is a rare event. The following conditions increase the risk of drug-induced TdP: a) Disease states/electrolyte levels (heart failure, structural cardiac disease, bradycardia, hypokalemia); b) Pharmacogenomic variables (presence of congenital LQTS, subclinical ion-channel mutations, history of or having a relative with history of drug-induced long QT/TdP); c) Pharmacodynamic and kinetic factors (high doses, women, elderly, metabolism inhibitors, combining two or more QT prolonging drugs, drugs that prolong the QT and increase QT dispersion, and drugs with multiple actions on ion channels). Because most of these conditions are preventable, careful evaluation of risk factors and increased knowledge of drug use associated with repolarization abnormalities are strongly recommended.

Loperamide Induced Torsades de Pointes: A Case Report and Review of the Literature

Abuse of over the counter drugs often gets overlooked by health care providers. Loperamide is one such over the counter drug that is often abused by drug addicts. We present here a case of a young male attaining euphoria from taking massive doses of loperamide. He developed Torsades de Pointes and subsequent cardiac arrest. We found similarities in the progression of myocardial electrical conduction abnormalities among loperamide and other previously known arrhythmogenic drugs. We intend to raise concern over the ease of availability of such drugs over the counter and increase the index of suspicion for over the counter drug abuse from our experience.

Importance of QT interval in clinical practice

Long QT interval is an important finding that is often missed by electrocardiogram interpreters. Long QT syndrome (inherited and acquired) is a potentially lethal cardiac channelopathy that is frequently mistaken for epilepsy. We present a case of long QT syndrome with multiple cardiac arrests presenting as syncope and seizures. The long QTc interval was aggravated by hypomagnesaemia and drugs, including clarithromycin and levofloxacin. Multiple drugs can cause prolongation of the QT interval, and all physicians should bear this in mind when prescribing these drugs.

Sustained release oral morphine as an alternative to methadone for the treatment of opioid-use disorder post Torsades de Pointes cardiac arrest

In most settings, approved medications for the treatment of opioid-use disorder include methadone and buprenorphine/naloxone, and in some settings, naltrexone. We present a case in which methadone administration was associated with an in-hospital episode of Torsades de Pointes in a patient who was subsequently maintained on sustained release oral morphine (SROM) for treatment of his opioid-use disorder. This transition was made in the context of long-term compliance to methadone maintenance, and with a previous adverse reaction to buprenorphine/naloxone precluding its use. The change to SROM, supported by emerging evidence, resulted in a reduction in the patient's measured QTc interval, prevention of further arrhythmias and continued abstinence from illicit opioid-use. In this context, we believe careful consideration should be given to the use of SROM.

The prevalence of long QT interval in post-operative intensive care unit patients

The severity of patient illnesses and medication complexity in post-operative critically ill patients increase the risk for a prolonged QT interval. We determined the prevalence of prolonged QTc in surgical intensive care unit (SICU) patients. We performed a prospective cross-sectional study over a 15-month period at a major academic center. SICU pre-admission and admission EKGs, patient demographics, and laboratory values were analyzed. QTc was evaluated as both a continuous and dichotomous outcome (prolonged QTc > 440 ms). 281 patients were included in the study: 92 % (n = 257) post-operative and 8 % (n = 24) non-operative. On pre-admission EKGs, 32 % of the post-operative group and 42 % of the non-operative group had prolonged QTc (p = 0.25); on post-admission EKGs, 67 % of the post-operative group but only 33 % of the non-operative group had prolonged QTc (p < 0.01). The average change in QTc in the post-operative group was +30.7 ms, as compared to +2 ms in the non-operative group (p < 0.01). On multivariable adjustment for long QTc as a dichotomous outcome, pre-admission prolonged QTc (OR 3.93, CI 1.93-8.00) and having had an operative procedure (OR 4.04, CI 1.67-9.83) were associated with developing prolonged QTc. For QTc as a continuous outcome, intra-operative beta-blocker use was associated with a statistically-significant decrease in QTc duration. None of the patients developed a lethal arrhythmia in the ICU. Prolonged QTc is common among post-operative SICU patients (67 %), however lethal arrhythmias are uncommon. The operative experience increases the risk for long QTc.

Ventricular arrhythmia in patients with prolonged QT interval during liver transplantation: two cases report

QT interval prolongation is associated with an increased risk of ventricular arrhythmia in various conditions. Cardiac electrophysiologic abnormalities including QT interval prolongation are well documented in patients with advanced liver cirrhosis. We report two cases of patients with QT interval prolongation on preoperative electrocardiography who exhibited repetitive ventricular arrhythmias with significant hemodynamic deterioration during liver transplantation. For the treatment and prevention of ventricular arrhythmias during the intraoperative period, we performed intravenous administration of lidocaine and isoproterenol, corrected imbalances of electrolytes including potassium and magnesium, and prepared a defibrillator. These cases emphasize that preoperative recognition of QT interval prolongation and adequate management to prevent fatal arrhythmias are important in patients undergoing liver transplantation.

Cavotricuspid isthmus ablation and subcutaneous monitoring device implantation in a 2-year-old baby with 2 SCN5A mutations, sinus node dysfunction, atrial flutter recurrences, and drug induced long-QT syndrome: a tricky case of pediatric overlap syndrome?

We describe the case of 2-year-old baby with compound heterozygosity for paternal and maternal alleles mutation of α-subunit of the cardiac sodium channel (SCN5A), sinus node dysfunction, atrial flutter recurrences, and drug induced long-QT syndrome. In this setting, we chose at first to perform linear ablation of cavotricuspid isthmus resulting in a bidirectional isthmus block. As a second step, we decided to implant a miniaturized loop recorder that, with a minimally invasive procedure, permits us to follow the development of the disease in order to define the future strategy. After 8 months follow-up, automatic daily loop-recorder transmissions disclose the complete absence of any arrhythmia along with asymptomatic ventricular pauses due to sinus node dysfunction. Echocardiography shows normal findings, in particular no left ventricular dysfunction.

Relationship between QT interval dispersion in acute stroke and stroke prognosis: a systematic review

BACKGROUND

QT dispersion (QTd) has been proposed as an indirect electrocardiography (ECG) measure of heterogeneity of ventricular repolarization. The predictive value of QTd in acute stroke remains controversial. We aimed to clarify the relationship between QTd and acute stroke and stroke prognosis.

METHODS

A systematic review of the literature was performed using prespecified medical subjects heading terms, Boolean logic, and the Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines. Eligible studies included ischemic or hemorrhagic stroke and provided QTd measurements.

RESULTS

Two independent reviewers identified 553 publications. Sixteen articles were included in the final analysis. There were a total of 888 stroke patients: 59% ischemic and 41% hemorrhagic. There was considerable heterogeneity in study design, stroke subtypes, ECG assessment time, control groups, and comparison groups. Nine studies reported a significant association between acute stroke and baseline QTd. Two studies reported that QTd increases are specifically related to hemorrhagic strokes, involvement of the insular cortex, right-side lesions, larger strokes, and increases in 3,4-dihydroxyphenylethylene glycol in hemorrhagic stroke. Three studies reported QTd to be an independent predictor of stroke mortality. One study each reported increases in QTd in stroke patients who developed ventricular arrhythmias and cardiorespiratory compromise.

CONCLUSIONS

There are few well-designed studies and considerable variability in study design in addressing the significance of QTd in acute stroke. Available data suggest that stroke is likely to be associated with increased QTd. Although some evidence suggests a possible prognostic role of QTd in stroke, larger and well-designed studies need to confirm these findings.

The potential contribution of ranolazine to Torsade de Pointe

Ranolazine is a novel anti-anginal agent acting through pharmacologic mechanism of inhibition of the late phase of the inward sodium current. In addition, it is a potent inhibitor of rapid delayed rectifier potassium currents, leading to prolongation of the QT interval. However, ranolazine has not yet described to be associated with Torsade de Pointes despite its QT-prolonging effect. In this case report, we describe a patient on ranolazine who developed Torsade de Pointes and discuss about the potential contribution of ranolazine to the development of Torsade de Pointes.

Overdrive pacing in a patient with incessant torsades de pointes

A 75-year-old man presented to the emergency department (ED) for syncope and was found to have intermittent runs of torsades de pointes (TdP). The patient had a medical history significant for disseminated coccidiomycosis and was on prophylactic fluconazole. Forty-eight hours prior to presentation, the patient had intractable nausea and vomiting and was unable to take anything orally. He eventually presented to the ED with severe hypokalaemia and hypomagnesaemia with repeat symptomatic runs of TdP, which required overdrive transvenous pacing. During the patient''s admission, his electrolytes were aggressively replete. Fluconazole was discontinued, and prior to discharge, the patient recovered fully with ECGs showing a normalisation of the QT interval.

Prevalence and factors associated with a prolonged QTc interval in a cohort of asymptomatic HIV-infected patients

We aimed to determine the prevalence of a prolonged QTc interval in HIV-infected patients and its related factors through an observational study of a cohort of asymptomatic HIV-infected outpatients. All patients underwent a standard 12-lead electrocardiogram and a transthoracic echocardiogram. Prolonged QTc was considered if it was >440 ms in men and >450 ms in women. Epidemiological, clinical, and laboratory data were collected and the patients completed a questionnaire about cardiovascular risk factors. The analysis of the potential risk factors for prolonged QTc was done by multivariate logistic regression. The study included 194 patients, 84% men, with a mean age of 46.3 years. The mean duration of HIV infection was 122.6 months and 27.8% had AIDS. Antiretroviral therapy was being taken by 185 (96.4%) patients, and 92.4% of them had an undetectable viral load. The mean CD4 lymphocyte count was 553/mm(3). A total of 24 (12.4%) patients had a prolonged QTc interval, with a mean QTc of 456 ms. The factors associated with a prolonged QTc were hyperlipidemia (OR 3.7, 95% CI: 1.3-10.3; p=0.01) and diastolic dysfunction (OR 6.7, 95% CI: 2.4-18.3; p=0.0001), while the use of atazanavir was associated with a lower likelihood of having a prolonged QTc (OR 0.11, 95% CI: 0.02-0.5; p=0.008). A prolonged QTc syndrome was not uncommon in this cohort of asymptomatic HIV-infected patients with good immunovirological control. It was associated with hyperlipidemia and diastolic dysfunction. The use of atazanavir, compared with other protease inhibitors, was associated with a lower likelihood of having a prolonged QTc.

Prevalence and determinants of QT interval prolongation in medical inpatients

BACKGROUND

QT interval prolongation carries an increased risk of torsade de pointes and death.

AIM

We sought to determine the prevalence of QT prolongation in medical inpatients and to identify determinants of this condition.

METHODS

We enrolled consecutive patients who were admitted to the internal medicine ward and who had an electrocardiogram performed within 24 h of admission. We collected information on baseline patient characteristics and the use of QT-prolonging drugs. Two blinded readers manually measured the QT intervals. QT intervals were corrected for heart rate using the traditional Bazett formula and the linear regression-based Framingham formula. We used logistic regression to identify patient characteristics and drugs that were independently associated with QTc prolongation.

RESULTS

Of 537 inpatients, 22.3% had a prolonged QTc based on the Bazett formula. The adjusted odds for QTc prolongation based on the Bazett correction were significantly higher in patients who had liver disease (OR 2.9, 95% CI: 1.5-5.6), hypokalaemia (OR 3.3, 95% CI: 1.9-5.6) and who were taking ≥1 QT-prolonging drug at admission (OR 1.7, 95% CI: 1.1-2.6). Overall, 50.8% of patients with QTc prolongation received additional QT-prolonging drugs during hospitalisation.

CONCLUSIONS

The prevalence of QTc prolongation was high among medical inpatients but depended on the method used to correct for heart rate. The use of QT-prolonging drugs, hypokalaemia and liver disease increased the risk of QTc prolongation. Many patients with QTc prolongation received additional QT-prolonging drugs during hospitalisation, further increasing the risk of torsade de pointes and death.

QT interval abnormalities: risk factors and perioperative management in long QT syndromes and Torsades de Pointes

Electrophysiological abnormalities of the QT interval of the standard electrocardiogram are not uncommon. Congenital long QT syndrome is due to mutations of several possible genes (genotype) that result in prolongation of the corrected QT interval (phenotype). Abnormalities of the QT interval can be acquired and are often drug-induced. Torsades de Pointes (TP) is an arrhythmia that is a result of aberrant repolarization/QT abnormalities. If not recognized and corrected quickly, QT interval abnormalities may precipitate potentially fatal ventricular dysrhythmias. The main mechanism responsible for the development of QT prolongation is blockade of the rapid component of the delayed rectifier potassium current (I kr), encoded for by the human-ether-a-go-go-related gene (hERG). The objectives of this review were (1) to describe the electrical pathophysiology of QT interval abnormalities, (2) to differentiate congenital from acquired QT interval abnormalities, (3) to describe the currently known risk factors for QT interval abnormalities, (4) to identify current drug-induced causes of acquired QT interval abnormalities, and (5) to recommend immediate and effective management strategies to prevent unanticipated dysrhythmias and deaths from QT abnormalities in the perioperative period.

Refractory ventricular tachycardia in a long QT syndrome child successfully controlled by left cardiac sympathetic denervation

Long QT syndrome is a congenital disorder accompanied by a high incidence of sudden cardiac death. β-adrenergic blockade is the therapy of choice, and it is successful in 75-80% of patients. However, for those in whom refractory arrhythmia or cardiac events are not prevented by medication, the literature suggests that left cardiac sympathetic denervation may be useful. Here we present a girl 20 months of age with refractory ventricular tachycardia due to long QT syndrome successfully treated by left cardiac sympathetic denervation. There was no significant complication.

QT Prolongation Complicated with Torsades de Pointes in Prosthetic Mitral Valve Endocarditis: A Case Report

We present the case of a 49-year-old male patient with prosthetic mitral valve endocarditis associated with QT prolongation and torsades de pointes. He was asymptomatic until the end of January 2012, when he was admitted to our hospital emergency unit because of syncope, fever, and suspicion of endocarditis. Cardiologic evaluation was requested and the transthoracic (TTE) and transesophageal (TEE) echocardiograms revealed vegetations on the prosthetic mitral valve. All cultures were positive for methicillin-sensitive Staphylococcus aureus. The corrected QT (QTc) interval was markedly prolonged upon admission (QTc 540 ms). He experienced torsades de pointes (TdP) several times and he was recovered after bystander cardiopulmonary resuscitation. The clinical course and the long QTc interval with deep inverted T wave were completely normalized 4 weeks after. He continued on triple antibiotic therapy for 45 days with a good revolution. The clinical features and the possible mechanisms of QT prolongation (inflammation, infection) of this patient are discussed.

QT interval prolongation in liver cirrhosis: innocent bystander or serious threat?

The ECG QT interval measures the length of ventricular systole. Its prolongation is essentially caused by a delayed repolarization phase, and is associated with an increased risk of ventricular arrhythmias and sudden death in several congenital and acquired conditions. Abnormalities in cardiac electrophysiology are well documented in patients with liver cirrhosis, and the prolonged QT interval has emerged as the electrophysiological hallmark of cirrhotic cardiomyopathy. This article will focus on: first, the epidemiology of QT interval prolongation in cirrhosis; second, the potential molecular mechanisms responsible for the pathogenesis of this electrophysiological abnormality and the putative role of circulating cardiotoxins; third, its prognostic meaning; and fourth, its clinical relevance, in terms of the association between the presence of a long QT interval and the occurrence of ventricular arrhythmias in cirrhotic patients treated with drugs known to increase the QT length or exposed to stressful conditions, such as liver transplantation, gastrointestinal bleeding and shock.

General anxiety, depression, and physical health in relation to symptoms of heart-focused anxiety- a cross sectional study among patients living with the risk of serious arrhythmias and sudden cardiac death

Objective

To investigate the role of three distinct symptoms of heart-focused anxiety (cardio-protective avoidance, heart-focused attention, and fear about heart sensations) in relation to general anxiety, depression and physical health in patients referred to specialized cardio-genetics outpatient clinics in Norway for genetic investigation and counseling.

Methods

Participants were 126 patients (mean age 45 years, 53.5% women). All patients were at higher risk than the average person for serious arrhythmias and sudden cardiac death (SCD) because of a personal or a family history of an inherited cardiac disorder (familial long QT syndrome or hypertrophic cardiomyopathy). Patients filled in, Hospital Anxiety and Depression Scale, Short-Form 36 Health Survey, and Cardiac Anxiety Questionnaire, two weeks before the scheduled counseling session.

Results

The patients experienced higher levels of general anxiety than expected in the general population (mean difference 1.1 (p < 0.01)). Hierarchical regression analyses showed that avoidance and fear was independently related to general anxiety, depression, and physical health beyond relevant demographic covariates (age, gender, having children) and clinical variables (clinical diagnosis, and a recent SCD in the family). In addition to heart-focused anxiety, having a clinical diagnosis was of importance for physical health, whereas a recent SCD in the family was independently related to general anxiety and depression, regardless of disease status.

Conclusion

Avoidance and fear may be potentially modifiable symptoms. Because these distinct symptoms may have important roles in determining general anxiety, depression and physical health in at-risk individuals of inherited cardiac disorders, the present findings may have implications for the further development of genetic counseling for this patient group.

Role of voltage-gated sodium, potassium and calcium channels in the development of cocaine-associated cardiac arrhythmias

Cocaine is a highly active stimulant that alters dopamine metabolism in the central nervous system resulting in a feeling of euphoria that with time can lead to addictive behaviours. Cocaine has numerous deleterious effects in humans including seizures, vasoconstriction, ischaemia, increased heart rate and blood pressure, cardiac arrhythmias and sudden death. The cardiotoxic effects of cocaine are indirectly mediated by an increase in sympathomimetic stimulation to the heart and coronary vasculature and by a direct effect on the ion channels responsible for maintaining the electrical excitability of the heart. The direct and indirect effects of cocaine work in tandem to disrupt the co-ordinated electrical activity of the heart and have been associated with life-threatening cardiac arrhythmias. This review focuses on the direct effects of cocaine on cardiac ion channels, with particular focus on sodium, potassium and calcium channels, and on the contributions of these channels to cocaine-induced arrhythmias. Companion articles in this edition of the journal examine the epidemiology of cocaine use (Wood & Dargan) and the treatment of cocaine-associated arrhythmias (Hoffmann).

Torsades de pointes and acute de novo heart failure in a young woman

Hypothyroidism is a rare metabolic cause of dilated cardiomyopathy that responds to substitution therapy. We report on a young woman who presented with torsades de pointes, severe heart failure and multiple organ failure due to longstanding untreated hypothyroidism. Administration of appropriate substitution therapy was followed by a cessation of ventricular arrhythmias and a complete recovery of the cardiac function.

The importance of the family history in caring for families with long QT syndrome and dilated cardiomyopathy

In potentially inherited cardiac diseases, the family history is of great importance. We looked at the way cardiologists take a family history in patients with idiopathic dilated cardiomyopathy (DCM) or long QT syndrome (LQTS) and whether this led to screening of relatives or other follow-up. We performed retrospective cross-sectional analyses of adult index patients with DCM or LQTS in a general hospital (GH) or a University Medical Center (UMC). We identified 82 index patients with DCM (34 GH; 48 UMC) and 20 with LQTS (all UMC) between 1996 and 2005. Mean follow-up was 58 months. A family history was recorded in 90% of both LQTS and DCM patients most of the cases restricted to first-degree family members. The genetic aspects, counseling and screening of family members was discussed significantly more often with LQTS than DCM patients (all P < 0.05). Also follow-up (screening of family members, DNA analysis and referral) was performed significantly more often in LQTS than DCM patients. Cardiologists in the UMC referred DCM index patients for genetic counseling more often than those in the GH (25% vs. 6%; P < 0.05). Only a few index patients with DCM were referred to a clinical genetics department. One-third of DCM cases and nearly all LQTS cases are familial. Since early recognition and treatment may reduce morbidity and mortality we recommend cardiologists take a more thorough family history and always consider referring to a clinical genetics department in such index patients.