Torsades de pointes with a severely prolonged QT interval induced by an initial low dose sotalol intake

The Arrhythmogenicity of Sotalol and its Role in Heart Failure: A Literature Review

ABSTRACT

According to the American Heart Association, approximately 6 million adults have been afflicted with heart failure in the United States in 2020 and are more likely to have sudden cardiac death accounting for approximately 50% of the cause of mortality. Sotalol is a nonselective β-adrenergic receptor antagonist with class III antiarrhythmic properties that has been mostly used for atrial fibrillation treatment and suppressing recurrent ventricular tachyarrhythmias. The use of sotalol in patients with left ventricular dysfunction is not recommended by the American College of Cardiology or American Heart Association because studies are inconclusive with conflicting results regarding safety. This article aims to review the mechanism of action of sotalol, the β-blocking effects on heart failure, and provide an overview of clinical trials on sotalol use and its effects in patients with heart failure. Small- and large-scale clinical trials have been controversial and inconclusive about the use of sotalol in heart failure. Sotalol has been shown to reduce defibrillation energy requirements and reduce shocks from implantable cardioverter-defibrillators. Torsades de Pointes is the most life-threatening arrhythmia that has been documented with sotalol use and occurs more commonly in women and heart failure patients. Thus far, mortality benefits have not been demonstrated with sotalol use and larger multicenter studies are required going forward.

Cardiac Biomarkers in the Setting of Asthma Exacerbations: a Review of Clinical Implications and Practical Considerations

PURPOSE OF REVIEW

The present paper aims to highlight clinical implications of elevated cardiac biomarkers and associated myocardial dysfunction in a variety of cardiac and non-cardiac scenarios in patients with an asthma exacerbation, and to propose a basic algorithm for cardiovascular evaluation and triage (and hence, for further management) of these patients primarily based on evaluation of cardiac biomarkers along with basic diagnostic modalities and specific cardiac symptoms in the hospital setting.

RECENT FINDINGS

Elevation of cardiac biomarkers in the setting of an asthma exacerbation mostly signifies a new-onset subclinical myocardial dysfunction/injury generally associated with certain asthma-related factors including acute hypoxemia and bronchodilator therapy, and usually has a limited prognostic value in these patients. On the other hand, elevation of these biomarkers in patients with an asthma exacerbation might also denote a variety of certain life-threatening cardiac or non-cardiac conditions associated with significant myocardial dysfunction (acute coronary syndromes (ACSs), sepsis, etc.) that might be masked by the rampant course of the asthma exacerbation, and hence, might possibly go undetected potentially aggravating the prognosis in a portion of these patients. In patients with an asthma exacerbation, it seems imperative to timely diagnose and manage emerging diverse clinical conditions particularly through the guidance of cardiac biomarkers and associated myocardial dysfunction patterns in an effort to improve overall prognosis in these patients.

Acquired drug-induced long QTc: new insights coming from a retrospective study

INTRODUCTION

Several drug classes (antiarrhythmics, antimicrobials, antidepressants, phenothiazines, opiates, prokinetics of digestive tract, etc.) have been related to ventricular hyperkinetic arrhythmias such as torsade de pointes (TdP). TdPs are usually heralded by an abnormal prolongation of heart rate-corrected QT interval on the electrocardiogram, so-called drug-induced long heart rate-corrected QT (diLQTc). We do not know to what extent the drug-induced QTc prolongation is able to predict malignant arrhythmias. Thus, we have retrospectively examined the clinical history of patients with diLQTc.

METHODS

The case record, concerning the period January 2008-December 2017, was collected from two hospitals. diLQTc was defined as drug-induced heart rate-corrected QT of ≥ 450 ms or ≥ 470 ms, respectively in male or female patients. The primary purpose was to verify whether in diLQTc patients the length of this electrocardiographic segment was associated with the risk of symptoms or events (TdP, ventricular fibrillation).

RESULTS

Seventy-three validated cases of diLQTc were gathered. Among them, the QTc duration was not able to predict the occurrence of symptoms or events (odds ratio, 0.998; 95% CI, 0.984 to 1.013; p = 0.8821). Likewise, a diQTc lasting longer than 500 ms compared to diQTc comprised between 450 and 500 ms was not associated with an increased risk of arrhythmic events.

CONCLUSIONS

In our diLQTc patients, QTc duration did not predict occurrence of symptoms, or arrhythmic events. Thus, other determinants should be postulated to clarify why sometimes diQTc prolongation propitiates ventricular malignant arrhythmias whereas in other cases this arrhythmogenic effect is lacking.

Malignant Ventricular Arrhythmias Resulting From Drug-Induced QTc Prolongation: A Retrospective Study

Background

Several drug classes (antiarrhythmics, antimicrobials, antidepressants, phenothiazines, opiates, prokinetics of digestive tract, etc.) have been related to ventricular hyperkinetic arrhythmias such as torsade de pointes (TdP). TdPs are usually heralded by an abnormal prolongation of heart rate-corrected QT interval on the electrocardiogram, so-called drug-induced long heart rate-corrected QT (diLQTc). We don’t know to what extent the drug-induced QTc prolongation is able to predict malignant arrhythmias. Thus we have retrospectively examined the clinical history of patients with diLQTc.

Methods

The case-record, concerning the period from January 2008 to December 2017, was collected from two hospitals. The diLQTc was defined as drug- induced heart rate-corrected QT of ≥ 450 ms or ≥ 470 ms, respectively in male or female patients. The primary purpose was to verify whether in diLQTc patients the length of this electrocardiographic segment was associated with the risk of symptoms or events (TdP, ventricular fibrillation).

Results

A total of 73 validated cases of diLQTc were gathered. Among them, the QTc duration was not able to predict the occurrence of symptoms or events (odds ratio: 0.998; 95% CI: 0.984 to 1.013; P = 0.8821). Likewise, a diQTc lasting longer than 500 ms compared to diQTc comprised between 450 and 500 ms was not associated with an increased risk of arrhythmic events.

Conclusions

In some probably genetically predisposed subjects, the occurrence of symptoms (dizziness, lipothymia, syncope ) and/or documented arrhythmic events (TdP), is related to intake of certain drugs (antiarrhythmics, antimicrobials such as quinolones and macrolides, etc.). Nevertheless, in our diLQTc patients, QTc duration didn’t predict occurrence of symptoms, or arrhythmic events. Thus, other determinants should be postulated to clarify why sometimes diQTc prolongation propitiates ventricular malignant arrhythmias whereas in other cases this arrhythmogenic effect is lacking.

Comparative effects of Guanfu base A and Guanfu base G on HERG K+ channel

BACKGROUND

Guanfu base A (GFA) and Guanfu base G (GFG) are chemicals isolated from Aconitum coreanum. The potassium channel encoded by the human ether-a-go-go related gene (HERG) plays an important role in repolarization of the cardiac action potential. The purpose of the present study was to investigate the effects of GFA and GFG on the HERG channel and its structure-function relationship.

METHODS

The effects of GFA and GFG were investigated in human embryonic kidney 293 (HEK293) cells transiently transfected with HERG complementary DNA using a whole-cell patch clamp technique.

RESULTS

GFA and GFG inhibited HERG channel current in concentration-, voltage-, and time-dependent manners. The IC50 for GFA and GFG was 1.64 mM and 17.9 μM, respectively. Both GFA and GFG shifted the activation curve in a negative direction and accelerated channel inactivation but showed no effect on the inactivation curve. Moreover, GFG also accelerated channel recovery from inactivation.

CONCLUSIONS

Both GFA and GFG blocked HERG channel current. This effect was stronger after GFG treatment rather than GFA treatment. This blockade was dependent on open and inactivated channel states. These results indicate that GFA could be a rather promising antiarrhythmic drug without severe side effects, whereas GFG could cause QT prolongation and requires further research.

QT interval prolongation and torsade de pointes

Torsade de pointes is a form of polymorphic ventricular tachycardia occurring in a setting of prolonged QT interval on surface electrocardiogram. Several drugs have been shown to prolong cardiac repolarization predisposing to torsade de pointes ventricular tachycardia. We present a case of torsade de pointes in a 72-year-old Italian woman in treatment with sotalol, sertraline, digoxin and acenocumarine.

QT interval prolongation, torsade de pointes and renal disease

Torsade de pointes is a form of polymorphic ventricular tachycardia occurring in a setting of prolonged QT interval on surface electrocardiogram. Several non-antiarrhythmic drugs including antibiotic and antipsychotic agents have been shown to prolong cardiac repolarization predisposing to torsade de pointes ventricular tachycardia. Blockade of the delayed rectifier (repolarising) potassium current and drug interactions with inhibitors of the cytochromes P450 (CYP)-mediated metabolism are the most common underlying mechanisms. Many antiarrhythmic drugs have been also implicated in prolonging QT interval and triggering torsades de pointes, especially during chronic therapy or in case of acute high dose toxicity. Progressive renal disease is associated from the earliest stages with increased QT interval and dispersal and with an increased risk of cardiovascular death, specifically sudden death. It has also been reported that cCorrected QT (QTc) interval prolongation and torsade de pointes are associated with end-stage renal disease (ESRD) and that they can be a cause of sudden death in ESRD. We present a case of torsade de pointes in a 82-year-old Italian woman with chronic renal failure.