Results of a curtailed randomized controlled trial, evaluating the efficacy and safety of azimilide in patients with implantable cardioverter-defibrillators: The SHIELD-2 trial

Promising Therapies for Atrial Fibrillation and Ventricular Tachycardia

Sudden cardiac death due to arrhythmias, such as atrial fibrillation or ventricular tachycardia, account for 15–20% of all deaths. Myocardial infarction increases the burden of atrial fibrillation and ventricular tachycardia by structural and electrical remodeling of the heart. The current management of new-onset atrial fibrillation includes electric cardioversion with very high conversion rates and pharmacologic cardioversion, with less a than 50% conversion rate. If atrial fibrillation cannot be converted, the focus becomes the control of the symptoms ensuring a constant rhythm and rate control, without considering other contributory factors such as autonomic imbalance. Recently, a huge success was obtained by developing ablation techniques or addressing the vagal nerve stimulation. On the other hand, ventricular tachycardia is more sensitive to drug therapies. However, in cases of non-responsiveness to drugs, the usual therapeutic choice is represented by stereotactic ablative therapy or catheter ablation. This review focuses on these newly developed strategies for treatment of arrhythmias in clinical practice, specifically on vernakalant and low-level tragus stimulation for atrial fibrillation and stereotactic ablative therapy for drug-refractory ventricular tachycardia. These therapies are important for the significant improvement of the management of atrial fibrillation and ventricular tachycardia, providing: (1) a safer profile than current therapies, (2) higher success rate than current solutions, (3) low cost of delivery.

Drug Interactions Affecting Antiarrhythmic Drug Use

Antiarrhythmic drugs (AAD) play an important role in the management of arrhythmias. Drug interactions involving AAD are common in clinical practice. As AADs have a narrow therapeutic window, both pharmacokinetic as well as pharmacodynamic interactions involving AAD can result in serious adverse drug reactions ranging from arrhythmia recurrence, failure of device-based therapy, and heart failure, to death. Pharmacokinetic drug interactions frequently involve the inhibition of key metabolic pathways, resulting in accumulation of a substrate drug. Additionally, over the past 2 decades, the P-gp (permeability glycoprotein) has been increasingly cited as a significant source of drug interactions. Pharmacodynamic drug interactions involving AADs commonly involve additive QT prolongation. Amiodarone, quinidine, and dofetilide are AADs with numerous and clinically significant drug interactions. Recent studies have also demonstrated increased morbidity and mortality with the use of digoxin and other AAD which interact with P-gp. QT prolongation is an important pharmacodynamic interaction involving mainly Vaughan-Williams class III AAD as many commonly used drug classes, such as macrolide antibiotics, fluoroquinolone antibiotics, antipsychotics, and antiemetics prolong the QT interval. Whenever possible, serious drug-drug interactions involving AAD should be avoided. If unavoidable, patients will require closer monitoring and the concomitant use of interacting agents should be minimized. Increasing awareness of drug interactions among clinicians will significantly improve patient safety for patients with arrhythmias.

Antiarrhythmic Drugs or Catheter Ablation in the Management of Ventricular Tachyarrhythmias in Patients With Implantable Cardioverter-Defibrillators: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

BACKGROUND

In patients with an implantable cardioverter-defibrillator (ICD), shocks are associated with increased morbidity and mortality. Therefore, we conducted this study to evaluate the efficacy and safety of antiarrhythmic drugs and catheter ablation (CA) in the treatment of ventricular tachyarrhythmias (VT) in patients with an ICD.

METHODS

An electronic database search for randomized controlled trials that evaluated antiarrhythmic drugs and CA in patients with ICD was conducted. The primary outcome was recurrent VT. Secondary outcomes were ICD shocks and any deaths. Bayesian and frequentist network meta-analyses were performed to calculate hazard ratios (HRs) and 95% credible intervals (CrIs)/CIs.

RESULTS

Twenty-two randomized controlled trials were identified (3828 total patients; age 64.3±11.4; 79% males). The use of amiodarone was associated with a significantly reduced rate of VT recurrence compared with control (HR=0.34 [95% CrI=0.15-0.74]; absolute risk difference=-0.23 [95% CrI=-0.23 to -0.09]; number needed to treat=4). Sotalol was associated with increased risk of VT recurrence compared with amiodarone (HR=2.88 [95% CrI=1.35-6.46]). Compared with control, amiodarone (HR=0.33 [95% CrI=0.15-0.76]; absolute risk difference=-0.17 [95% CrI=-0.32 to -0.06]; number needed to treat=6) and CA (HR=0.52 [95% CrI=0.30-0.89; absolute risk difference=-0.12 [95% CrI=-0.24 to -0.03]; number needed to treat=8) were associated with significantly reduced ICD shocks. Compared with amiodarone, sotalol was associated with significantly increased ICD shocks (HR=2.70 [95% CrI=1.17-6.71]). The rate of death was not significantly different between the competing strategies. The node-splitting method showed no inconsistency.

CONCLUSIONS

Among patients with an ICD, amiodarone significantly reduced VT recurrence and ICD shocks, while CA reduced ICD shocks. Sotalol significantly increased VT recurrence and ICD shocks compared with amiodarone. The long-term side effects of amiodarone and early complications of CA should be weighed carefully according to specific patient characteristics.

Prevention of Recurrent Ventricular Tachycardia in Patients With Implantable Cardioverter Defibrillators-A Network Meta-analysis

BACKGROUND

The optimal management for the prevention of recurrent ventricular tachycardia in patients with implantable cardioverter-defibrillators (ICDs) offers a challenge with no set guidelines regarding which therapy offers a best safety and efficacy profile.

STUDY QUESTION

Which therapeutic strategy, among antiarrhythmic drugs and catheter ablation (CA), offers the most effective and safe approach in patients with ICDs?

DATA SOURCES

Randomized controlled trials (RCTs) comparing the efficacy and safety of antiarrhythmic drugs or CA against a placebo group. RCTs were identified from a comprehensive search in PubMed, Embase, and Cochrane library.

STUDY DESIGN

Our outcomes of interest were reductions in appropriate ICD shocks, inappropriate ICD shocks, and overall mortality. We used the event rates in both groups, and then using a frequentist approach employing a graph theory methodology, we constructed a network meta-analysis model.

RESULTS

Fourteen RCTs with 3815 participants and 6 different interventions treatments were included in our network meta-analysis. The most effective treatment for the prevention of recurrent ventricular tachycardia after ICD is amiodarone followed by CA. Amiodarone is most effective in the reduction of appropriate and inappropriate ICD shocks with an odds ratio (OR) of 0.29 [95% confidence interval (CI), 0.11-0.74] and 0.15 (95% CI, 0.04-0.60), respectively. CA was effective in the reduction of appropriate ICD shocks (OR, 0.41; 95% CI, 0.20-0.87), whereas sotalol was effective in the reduction of inappropriate ICD shocks (OR, 0.46; 95% CI, 0.22-0.95). There was no significant reduction in the overall mortality from any therapy. There was a trend of increased mortality associated with amiodarone therapy (OR, 2.40; 95% CI, 0.92-6.26).

CONCLUSIONS

Amiodarone remains the most efficacious therapy for the reduction of appropriate and inappropriate shocks in patients with ICD. No therapy resulted in mortality reduction, but amiodarone showed a trend toward increased mortality.

Anti-arrhythmic drug therapy in implantable cardioverter-defibrillator recipients

Implantable cardioverter-defibrillators (ICDs) have revolutionized the primary and secondary prevention of patients with ventricular arrhythmias. However, the adverse effects of appropriate or inappropriate shocks may require the adjunctive use of anti-arrhythmic drugs (AADs). Beta blockers are the cornerstone of pharmacological primary and secondary prevention of ventricular arrhythmias. In addition to their established efficacy at reducing the incidence of ventricular arrhythmias, beta-blockers are safe with few side effects. Amiodarone is superior to beta blockers and sotalol for the prevention of ventricular arrhythmia recurrence. However, long-term amiodarone use is associated with significant side effects that limit its utility. Sotalol and mexiletine are the main alternatives to amiodarone with a better side effect profile though they are less efficacious at preventing ventricular arrhythmia recurrence. Dofetilide, azimilide and ranolazine are emerging as therapeutic options for secondary prevention; more studies are needed to assess efficacy and safety in comparison to currently used agents. Beta blockers and amiodarone are the mainstay of therapy in patients experiencing electrical storm; their use reduces the frequency of ventricular arrhythmias and ICD intervention as well as affording time until catheter ablation can be considered.

EHRA White Paper: knowledge gaps in arrhythmia management—status 2019

Clinicians accept that there are many unknowns when we make diagnostic and therapeutic decisions. Acceptance of uncertainty is essential for the pursuit of the profession: bedside decisions must often be made on the basis of incomplete evidence. Over the years, physicians sometimes even do not realize anymore which the fundamental gaps in our knowledge are. As clinical scientists, however, we have to halt and consider what we do not know yet, and how we can move forward addressing those unknowns. The European Heart Rhythm Association (EHRA) believes that scanning the field of arrhythmia / cardiac electrophysiology to identify knowledge gaps which are not yet the subject of organized research, should be undertaken on a regular basis. Such a review (White Paper) should concentrate on research which is feasible, realistic, and clinically relevant, and should not deal with futuristic aspirations. It fits with the EHRA mission that these White Papers should be shared on a global basis in order to foster collaborative and needed research which will ultimately lead to better care for our patients. The present EHRA White Paper summarizes knowledge gaps in the management of atrial fibrillation, ventricular tachycardia/sudden death and heart failure.

New formula for defining "normal" and "prolonged" QT in patients with bundle branch block

OBJECTIVES

To predict the QT interval in the presence of normal QRS for patients with left bundle branch block (LBBB).

BACKGROUND

There is no acceptable method for simple and reliable QT correction for patients with bundle branch block (BBB).

METHODS

We measured the QT interval in patients with new onset LBBB who had a recent electrocardiogram with narrow QRS for comparison. 48 patients who developed in-hospital LBBB were studied. Patients who had similar heart rate before and after LBBB were included. We used linear regression, the Bogossian method, and our new fixed QRS replacement method to evaluate the most reliable correction method.

RESULTS

JTc (QTc-QRS) interval was preserved before and after LBBB (328.9 ± 25.4 ms before LBBB vs. 327.3 ms post LBBB (p = 0.550). Mean predicted preLBBB QTc difference was 1.3 ms, -21.3 ms and 1.6 ms for the three methods respectively (p < 0.001 for Bogossian comparison with the other methods). Coefficients of correlation (R) between actual preLBBB QTc with predicted preLBBB QTc were 0.707, 0.683 and 0.665 respectively (p > 0.3 for R comparisons between all methods). The average absolute difference in preLBBB QTc was 15.5 ms and 16.7 ms for the regression and fixed-gender methods (p value between the two = 0.321) and 25.5 ms for the Bogossian method, which was found to be significantly underperforming.

CONCLUSIONS

In patients with LBBB, replacing of the QRS duration after deriving the QTc interval with a fixed value of 88 ms for female and 95 ms for male provides a simple and reliable method for predicting the QTc before the development of LBBB.