Incidence, Predictors, and Outcome Associated With Ventricular Tachycardia or Fibrillation in Patients Undergoing Primary Percutaneous Coronary Intervention for Acute Myocardial Infarction

BACKGROUND

The characteristics and clinical outcomes associated with sustained ventricular tachycardia and fibrillation (VT/VF) in Japanese acute myocardial infarction (AMI) patients remain unknown.

METHODS AND RESULTS

Consecutive AMI patients (n=1,941) transferred to the Hirosaki University Hospital and treated with primary percutaneous coronary intervention (PCI) within 12 h of onset were retrospectively studied. The incidence of VT/VF during hospitalization was 8.3%, and 75% of cases occurred by the end of PCI. Independent predictors associated with VT/VF occurrence by the end of PCI and after PCI, respectively, were identified. Additionally, the differences between patients with VT and VF were examined, which revealed that the characteristics of patients and predictors for VT and VF were clearly different. Additionally, the QRS duration during VT was measured, which demonstrated the possible involvement of Purkinje fibers for VT in the acute phase of AMI. Of the patients with VT/VF, 12% required ECMO support due to refractory VT/VF despite intravenous antiarrhythmic agents such as β-blockers, amiodarone, and nifekalant. Among the patients discharged alive, 1,690 were followed up for a mean of 3.7 years. VT/VF occurrence during hospitalization did not affect the mid-term clinical outcomes even in patients with VT.

CONCLUSIONS

The results clearly indicated that VT/VF is still a serious complications of AMI. We need to identify patients at high risk of developing VT/VF for careful observation and appropriate intervention.

Clinical and Laboratory Predictors of Long-Term Outcomes after Catheter Ablation for a Ventricular Electrical Storm

Background

Ventricular electrical storm (VES) is characterized by the occurrence of multiple episodes of sustained ventricular arrhythmias (VA) over a short period of time. Radiofrequency ablation (RFA) has been reported as an effective treatment in patients with ventricular tachycardia (VT).

Objective

The aim of the present study was to indicate the short-term and long-term predictors of recurrent VA after RFA was performed due to VES.

Methods

A retrospective, single-centre study included patients, who had undergone RFA due to VT between 2012 and 2021. In terms of the short-term (at the end of RFA) effectiveness of RFA, the following scenarios were distinguished: complete success: inability to induce any VT; partial success: absence of clinical VT; failure: inducible clinical VT. In terms of the long-term (12 months) effectiveness of RFA, the following scenarios were distinguished: effective ablation: no recurrence of any VT; partially successful ablation: VT recurrence; ineffective ablation: VES recurrence.

Results

The study included 62 patients. Complete short-term RFA success was obtained in 77.4% of patients. The estimated cumulative VT-free survival and VES-free survival were, respectively, 28% and 33% at the 12-month follow-up. Ischemic cardiomyopathy and complete short-term RFA success were predictors of long-term RFA efficacy. Neutrophil to lymphocyte ratio (NLR) and GFR <60 mL/min/1.73 m2 were associated with VES recurrence. NLR ≥2.95 predicted VT and/or VES recurrence with a sensitivity of 66.7% and specificity of 72.2%.

Conclusion

Ischemic cardiomyopathy and short-term complete success of RFA were predictors of no VES recurrence during the 12-month follow-up, while NLR and GFR <60 ml/min/1.73 m2 were associated with VES relapse.

Effectiveness and safety of mexiletine in patients at risk for (recurrent) ventricular arrhythmias: a systematic review

While mexiletine has been used for over 40 years for prevention of (recurrent) ventricular arrhythmias and for myotonia, patient access has recently been critically endangered. Here we aim to demonstrate the effectiveness and safety of mexiletine in the treatment of patients with (recurrent) ventricular arrhythmias, emphasizing the absolute necessity of its accessibility. Studies were included in this systematic review (PROSPERO, CRD42020213434) if the efficacy or safety of mexiletine in any dose was evaluated in patients at risk for (recurrent) ventricular arrhythmias with or without comparison with alternative treatments (e.g. placebo). A systematic search was performed in Ovid MEDLINE, Embase, and in the clinical trial registry databases ClinicalTrials.gov and ICTRP. Risk of bias were assessed and tailored to the different study designs. Large heterogeneity in study designs and outcome measures prompted a narrative synthesis approach. In total, 221 studies were included reporting on 8970 patients treated with mexiletine. Age ranged from 0 to 88 years. A decrease in ventricular arrhythmias of >50% was observed in 72% of the studies for pre-mature ventricular complexes, 64% for ventricular tachycardia, and 33% for ventricular fibrillation. Electrocardiographic effects of mexiletine were small; only in a subset of patients with primary arrhythmia syndromes, a relative (desired) QTc decrease was reproducibly observed. As for adverse events, gastrointestinal complaints were most frequently observed (33% of the patients). In this systematic review, we present all the currently available knowledge of mexiletine in patients at risk for (recurrent) ventricular arrhythmias and show that mexiletine is both effective and safe.

Mexiletine for recurrent ventricular tachycardia in adult patients with structural heart disease and implantable cardioverter defibrillator: an EHRA systematic review

The aim of the study was to systematically review evidence on the effectiveness and safety of oral mexiletine administered in monotherapy or in combination with other antiarrhythmic drugs for recurrent ventricular arrhythmia (ventricular tachycardia/ventricular fibrillation, VT/VF) in adult patients with structural heart disease (SHD) and implantable cardioverter defibrillators (ICDs). We systematically searched MEDLINE, Embase, and CENTRAL databases from inception to 27 August 2021 for prospective and retrospective studies investigating mexiletine in the target population. The main outcome was the reduction of ICD therapy. The main safety outcome was the presence of any serious adverse events (SAEs) leading to mexiletine discontinuation. Study quality was assessed using the Cochrane risk of bias tool or the Newcastle–Ottawa scale. Four studies comprising 86 mexiletine recipients were included in the review. We also obtained individual data of 50 patients from two studies. Ischaemic cardiomyopathy (ICM) was present in 86% of patients. The quality of included studies was moderate/low. A narrative review was undertaken as studies varied widely in terms of study population and treatment. Across studies, mexiletine treatment (with or without amiodarone) seemed to consistently reduce the number of ICD therapies especially in a population where catheter ablation (CA) was unsuccessful or contraindicated. In ICM patients deemed eligible for CA, mexiletine seemed to be inferior to CA. Mexiletine was discontinued in 14% of cases, mainly for gastrointestinal or neurological SAE. Mexiletine seems to be an option for the long-term treatment of recurrent VT/VF in adult patients with SHD, especially ICM, and ICD in whom CA was unsuccessful or not suitable.

Characteristics of ventricular tachycardia and long-term treatment outcome in patients with dilated cardiomyopathy complicated by lamin A/C gene mutations

BACKGROUND

Dilated cardiomyopathy caused by lamin A/C gene (LMNA) mutation is complicated with atrioventricular (AV) conduction disturbances, malignant ventricular arrhythmias, and progressive severe heart failure. Radiofrequency catheter ablation (RFCA) of ventricular tachycardia (VT) has been reported to be challenging due to the high recurrence rate in patients with LMNA-related cardiomyopathy. However, electrophysiological and histopathological characteristics of VT substrate remain to be fully elucidated.

METHODS AND RESULTS

We experienced 6 familial patients with LMNA-related cardiomyopathy in 3 pedigrees (6 males, 43.7±4.5 [SD] years). All patients had first VT attack at 50±6.6 [SD] years of age, and 4 underwent RFCA for incessant VT. Their electrocardiograms during VT showed similar QRS morphologies, characterized by an inferior axis, SR pattern in aVR, and QS pattern in aVL, suggesting the origin of the basal anterior ventricle. Indeed, the VTs had multiple exits around the basal anterior ventricular septum in all RFCA cases. Although we performed multiple RFCA procedures including epicardial ablation and surgical cryoablation, all cases experienced VT recurrences in 4.5±6.4 [SD] months after last procedure. All patients developed end-stage heart failure with frequent VT events, and died at 59.5±3.6 years of age (severe heart failure in 5 and lung disease in 1). In three autopsy cases with RFCA, fibrofatty degeneration was noted in the AV node. In addition, in the deep basal ventricular septum, inhomogenous fibrotic degenerated tissue was noted beyond the reach of RF lesions.

CONCLUSIONS

These results demonstrate that patients with LMNA-related cardiomyopathy are characterized by VTs refractory to RFCA probably because of the deep intramural focus at the basal ventricular septum, resulting in poor prognosis with progressive severe heart failure despite all available optimized therapies. Thus, we should consider heart transplantation in their early 50s when several VT events begin to occur.

Editor's Choice-The treatment of electrical storm: an educational review

Electrical storm is characterised by a state of severe electrical instability that occurs in a rare combination of circumstances, and may lead to multiple implantable cardioverter defibrillator shocks and haemodynamic instability, and possible death. The main goal of treating electrical storm is to eliminate the trigger and modify the substrate of the arrhythmia. The aim of this educational review is to provide information for a better understanding of the underlying mechanisms and therefore help to improve the treatment of electrical storm patients.

Catheter ablation in the treatment of electrical storm: Integrative review

BACKGROUND

The incidence of electrical storm (ES) has been increasing with the rise of the indicated uses of implantable cardioverter defibrillators (ICDs). It is estimated that 20% of patients will evolve to have this complication. Ablative therapy stands out as the treatment for this condition when it is refractory to antiarrhythmic treatment. The objective was to define the current role of catheter ablation in the treatment of electrical storm.

METHODS

An integrative literature review was performed using the PubMed and BVS databases. All identified articles were screened and verified for eligibility by the authors.

RESULTS

Twenty-five out of the initial 951 articles were used in the final analysis. The categories listed for analysis included indication for ablation in ES, modality of the approach, therapeutic success, complications related to the procedure, mortality and cardiovascular follow-up and alternative therapeutic modalities by frequency of these categories in the articles researched.

CONCLUSION

Catheter ablation is the initial therapy for patients with ischemic cardiomyopathy (ICM) and ES. The endocardial approach presents more relevant success rates than the other therapeutic methods presented.