Implantable Cardioverter-defibrillator Shocks Research Articles

Active Arrhythmia Pattern: A Novel Predictor of ICD Shocks-A Subanalysis From the PARTITA Study.

In the PARTITA trial (Does Timing of Ventricular Tachycardia Ablation Affect Prognosis in Patients With an Implantable Cardioverter Defibrillator?), antitachycardia pacing (ATP) predicted the occurrence of implantable cardioverter defibrillator (ICD) shocks. Catheter ablation of ventricular tachycardia after the first shock reduced the risk of death or worsening heart failure. A threshold of ATPs that might warrant an ablation procedure before ICD shocks is unknown. Our aim was to identify a threshold of ATPs and clinical features that predict the occurrence of shocks and cardiovascular events. We analyzed data from 517 patients in phase A of the PARTITA study. We used classification and regression tree analysis to develop and test a risk stratification model based on arrhythmia patterns and clinical data to predict ICD shocks. Secondary end points were worsening heart failure and cardiovascular hospitalization. Classification and regression tree classified patients into 6 leaves by increasing shock probability. Patients treated with ≥5 ATPs in 6 months (active arrhythmia pattern) had the highest risk of ICD shocks (93% and 86%, training and testing samples, respectively). Patients without ATPs had the lowest (1% and 2%). Other predictors included left ventricle ejection fraction<35%, age of <60 years, and obesity. Survival analysis revealed a higher risk of worsening heart failure (hazard ratio, 5.45 [95% CI, 1.62-18.4]; P=0.006) and cardiovascular hospitalization (hazard ratio, 7.29 [95% CI, 3.66-14.5]; P<0.001) for patients with an active arrhythmia pattern compared with those without ATPs. Patients with an active arrhythmia pattern (≥5 ATPs in 6 months) are associated with an increased risk of ICD shocks, as well as heart failure hospitalization and cardiovascular hospitalization. These data suggest that additional treatments may be helpful to this high-risk group as a preventive strategy to reduce the incidence of major events. Further prospective randomized trials are needed to confirm the benefits of early ventricular tachycardia ablation in this setting.

Catheter Ablation for Channelopathies: When Is Less More?

Ventricular fibrillation (VF) is a common cause of sudden cardiac death in patients with channelopathies, particularly in the young population. Although pharmacological treatment, cardiac sympathectomy, and implantable cardioverter defibrillators (ICD) have been the mainstay in the management of VF in patients with channelopathies, they are associated with significant adverse effects and complications, leading to poor quality of life. Given these drawbacks, catheter ablation has been proposed as a therapeutic option for patients with channelopathies. Advances in imaging techniques and modern mapping technologies have enabled increased precision in identifying arrhythmia triggers and substrate modification. This has aided our understanding of the underlying pathophysiology of ventricular arrhythmias in channelopathies, highlighting the roles of the Purkinje network and the epicardial right ventricular outflow tract in arrhythmogenesis. This review explores the role of catheter ablation in managing the most common channelopathies (Brugada syndrome, congenital long QT syndrome, short QT syndrome, and catecholaminergic polymorphic ventricular tachycardia). While the initial results for ablation in Brugada syndrome are promising, the long-term efficacy and durability of ablation in different channelopathies require further investigation. Given the genetic and phenotypic heterogeneity of channelopathies, future studies are needed to show whether catheter ablation in patients with channelopathies is associated with a reduction in VF, and psychological distress stemming from recurrent ICD shocks, particularly relative to other available therapeutic options (e.g., quinidine in high-risk Brugada patients).

Impact of a Chronic Total Coronary Occlusion on the Incidence of Appropriate Implantable Cardioverter-Defibrillator Shocks and Mortality: A Substudy of the Dutch Outcome in ICD Therapy (DO-IT)) Registry.

Chronic total coronary occlusions (CTO) substantially increase the risk for sudden cardiac death. Among patients with chronic ischemic heart disease at risk for sudden cardiac death, an implantable cardioverter defibrillator (ICD) is the favored therapy for primary prevention of sudden cardiac death. This study sought to investigate the impact of CTOs on the risk for appropriate ICD shocks and mortality within a nationwide prospective cohort. This is a subanalysis of the nationwide Dutch-Outcome in ICD Therapy (DO-IT) registry of primary prevention ICD recipients in The Netherlands between September 2014 and June 2016 (n=1442). We identified patients with chronic ischemic heart disease (n=663) and assessed available coronary angiograms for CTO presence (n=415). Patients with revascularized CTOs were excluded (n=79). The primary end point was the composite of all-cause mortality and appropriate ICD shocks. Clinical follow-up was conducted for at least 2 years. A total of 336 patients were included, with an average age of 67±9 years, and 20.5% was female (n=69). An unrevascularized CTO was identified in 110 patients (32.7%). During a median follow-up period of 27 months (interquartile range, 24-32), the primary end point occurred in 21.1% of patients with CTO (n=23) compared with 11.9% in patients without CTO (n=27; P=0.034). Corrected for baseline characteristics including left ventricular ejection fraction, and the presence of a CTO was an independent predictor for the primary end point (hazard ratio, 1.82 [95% CI, 1.03-3.22]; P=0.038). Within this nationwide prospective registry of primary prevention ICD recipients, the presence of an unrevascularized CTO was an independent predictor for the composite outcome of all-cause mortality and appropriate ICD shocks.

Electrical storm after left ventricular assist device (LVAD) implantation.

Ventricular tachycardia storm or electrical storm (ES) is a common complication following left ventricular assist device (LVAD) implantation. The factors contributing to ES and outcomes are less studied. The study aimed to determine the factors associated with ES and the probability of survival in patients undergoing LVAD in three tertiary centers over a span of 15 years. We performed a retrospective cohort study on all patients who underwent LVAD implantation at the Mayo Clinic (Rochester, Phoenix, and Jacksonville) from January 1, 2006to December 31, 2020. ES was defined as ≥3 episodes of sustained ventricular tachycardia over a period of 24 h with no identifiable reversible cause. Detailed chart reviews of the electronic health records within the Mayo Clinic and outside medical records were performed. A total of 883 patients who underwent LVAD implantation were included in our study. ES occurred in 7% (n = 61) of patients with a median of 13 days (interquartile range [IQR]: 5-297 days) following surgery. We found 57% of patients (n = 35) developed ES within 30 days, while 43% (n = 26) patients developed ES at a median of 545 (IQR 152-1032) days after surgery. Following ES, 26% of patients died within 1 year. Patients with ES had a significant association with a history of ventricular arrhythmias and implantable cardioverter defibrillator(ICD) shocks before the procedure. ES was significantly associated with reduced survival compared to patients without ES(hazards ratio [HR]: 1.92, 95% CI: 1.39-2.64, p < .001). Following LVAD implantation, the rate of ES was 7% with majority of ES occurring within 30 days of LVAD. Risk factors for ES included pre-implant history of ventricular arrhythmias and ICD shock. ES was significantly associated with reduced survival compared to patients without ES.

An international multicenter cohort study on implantable cardioverter-defibrillators for the treatment of symptomatic children with catecholaminergic polymorphic ventricular tachycardia

BackgroundCatecholaminergic polymorphic ventricular tachycardia (CPVT) may cause sudden cardiac death (SCD) despite medical therapy. Therefore, implantable cardioverter-defibrillators (ICDs) are commonly advised. However, there are limited data on the outcomes of ICD use in children. ObjectiveThe purpose of this study was to compare the risk of arrhythmic events in pediatric patients with CPVT with and without ICD. MethodsWe compared the risk of SCD in patients with RYR2 (ryanodine receptor 2) variants and phenotype-positive symptomatic patients with CPVT with and without ICD who were younger than 19 years and had no history of sudden cardiac arrest at phenotype diagnosis. The primary outcome was SCD; secondary outcomes were composite end points of SCD, sudden cardiac arrest, or appropriate ICD shocks with or without arrhythmic syncope. ResultsThe study included 235 patients, 73 with ICD (31.1%) and 162 without ICD (68.9%). Over a median follow-up of 8.0 years (interquartile range 4.3–13.4 years), SCD occurred in 7 patients (3.0%), of whom 4 (57.1%) were noncompliant with medications and none had an ICD. Patients with ICD had a higher risk of both secondary composite outcomes (without syncope: hazard ratio 5.85; 95% confidence interval 3.40–10.09; P < .0001; with syncope: hazard ratio 2.55; 95% confidence interval 1.50–4.34; P = .0005). Thirty-one patients with ICD (42.5%) experienced appropriate shocks, 18 (24.7%) inappropriate shocks, and 21 (28.8%) device-related complications. ConclusionSCD events occurred only in the no ICD group and in those not on optimal medical therapy. Patients with ICD had a high risk of appropriate and inappropriate shocks, which may be reduced with appropriate device programming. Severe ICD complications were common, and risks vs benefits of ICDs need to be considered.

Stroke after implantable cardioverter-defibrillator shocks in patients with heart failure.

Stroke after implantable cardioverter-defibrillator shocks in patients with heart failure.

Selection of social comparison standards in cardiac patients with and without experienced defibrillator shock

Patients with an implantable cardioverter-defibrillator (ICD) often report psychological distress. Literature suggests that patients with physical disease often compare their well-being and coping to fellow patients. However, we lack knowledge on social comparison among patients with ICD. In this study, we examined psychological distress and social comparison selection in patients with (ICD+) and without experienced ICD shocks (ICD−). We theorized that relative to ICD− patients, those with ICD+ display higher levels of psychological distress and thereby compare more frequently with fellow patients with more severe disease, but better disease coping and try to identify more strongly with these standards to improve their own coping. We recruited 92 patients with (ICD+, n = 38) and without an experienced ICD shock (ICD−, n = 54), who selected one of four comparison standards varying in disease severity and coping capacity. Relative to ICD−, ICD+ patients reported higher levels of device-related distress, but there were no significant differences in anxiety, depression, or quality of life. ICD+ patients selected more often comparison standards with poor coping and, irrespective of standard choice, displayed more negative mood following comparison. Our results show that ICD+ patients tend to perform unfavorable comparisons to fellow patients, which might explain higher psychological distress and worse coping. These findings warrant further research into social comparison as a relevant coping mechanism in ICD patients.

The impact of supraventricular arrhythmias on the outcomes of guideline-compliant implantable cardioverter defibrillator programming.

Several implantable cardioverter defibrillators (ICD) programming strategies are applied to minimize ICD therapy, especially unnecessary therapies from supraventricular arrhythmias (SVA). However, it remains unknown whether these optimal programming recommendations only benefit those with SVAs or have any detrimental effects from delayed therapy on those without SVAs. This study aims to assess the impact of SVA on the outcomes of ICD programming based on 2015 HRS/EHRA/APHRS/SOLAECE expert consensus statement and 2019 focused update on optimal ICD programming and testing guidelines. Consecutive patients who underwent ICD insertion for primary prevention were classified into four groups based on SVA status and ICD programming: (1) guideline-concordant group (GC) with SVA, (2)GC without SVA, (3) nonguideline concordant group (NGC) with SVA, and (4)NGC without SVA. Cox proportional hazard models were analyzed for freedom from ICD therapies, shock, and mortality. Seven hundred and seventy-two patients (median age, 64 years) were enrolled. ICD therapies were the most frequent in NGC with SVA (24.0%), followed by NGC without SVA (19.9%), GC without SVA (11.6%), and GC with SVA (8.1%). Guideline concordant programming was associated with 68% ICD therapy reduction (HR 0.32, p = .007) and 67% ICD shock reduction (HR 0.33, p = .030) in SVA patients and 44% ICD therapy reduction in those without SVA (HR 0.56, p = .030). Programming ICDs in primary prevention patients based on current guidelines reduces therapy burden without increasing mortality in both SVA and non-SVA patients. A greater magnitude of reduced ICD therapy was found in those with supraventricular arrhythmias.

Efficacy and Safety of Stereotactic Radiotherapy in Patients With Recurrent Ventricular Tachycardias: The Czech Experience

BackgroundStereotactic arrhythmia radiotherapy (STAR) has been proposed recently in patients with refractory ventricular tachycardia (VT). ObjectivesThe purpose of this study was to describe the efficacy and safety of STAR in the Czech Republic. MethodsVT patients were recruited in 2 expert centers after at least 1 previously failed catheter ablation (CA). A precise strategy of target volume determination and CA was used in 17 patients treated from December 2018 until June 2022 (EFFICACY cohort). This group, together with an earlier series of 19 patients with less-defined treatment strategies, composed the SAFETY cohort (n = 36). A dose of 25 Gy was delivered. ResultsIn the EFFICACY cohort, the burden of implantable cardioverter-defibrillator therapies decreased, and this drop reached significance for direct current shocks (1.9 ± 3.2 vs 0.1 ± 0.2 per month; P = 0.03). Eight patients (47%) underwent repeated CA for recurrences of VT during 13.7 ± 11.6 months. In the SAFETY cohort (32 procedures, follow-up >6 months), 8 patients (25%) presented with a progression of mitral valve regurgitation, and 3 (9%) required intervention (median follow-up of 33.5 months). Two cases of esophagitis (6%) were seen with 1 death caused by the esophago-pericardial fistula (3%). A total of 18 patients (50%) died during the median follow-up of 26.9 months. ConclusionsAlthough STAR may not be very effective in preventing VT recurrences after failed CA in an expert center, it can still modify the arrhythmogenic substrate, and when used with additional CA, reduce the number of implantable cardioverter-defibrillator shocks. Potentially serious sides effects require close follow-up.

Insights into adherence to medication and lifestyle recommendations in an international cohort of patients with catecholaminergic polymorphic ventricular tachycardia.

In patients with catecholaminergic polymorphic ventricular tachycardia (CPVT), a rare inherited arrhythmia syndrome, arrhythmic events can be prevented by medication and lifestyle recommendations. In patients who experience breakthrough arrhythmic events, non-adherence plays an essential role. We aimed to investigate the incidence and potential reasons for non-adherence to medication and lifestyle recommendations in a large, international cohort of patients with CPVT. An online multilingual survey was shared with CPVT patients worldwide by their cardiologists, through peer-recruitment, and on social media from November 2022 until July 2023. Self-reported non-adherence was measured using the validated Medication Adherence Rating Scale (MARS) and a newly developed questionnaire about lifestyle. Additionally, validated questionnaires were used to assess potential reasons for medication non-adherence. Two-hundred-and-eighteen patients completed the survey, of whom 200 (92%) were prescribed medication [122 (61%) female; median age 33.5 years (interquartile range: 22-50)]. One-hundred-and-three (52%) were prescribed beta-blocker and flecainide, 85 (43%) beta-blocker, and 11 (6%) flecainide. Thirty-four (17%) patients experienced a syncope, aborted cardiac arrest or appropriate implantable cardioverter defibrillator shock after diagnosis. Nineteen (13.4%) patients were exercising more than recommended. Thirty (15%) patients were non-adherent to medication. Female sex [odds ratio (OR) 3.7, 95% confidence interval (CI) 1.3-12.0, P = 0.019], flecainide monotherapy compared to combination therapy (OR 6.8, 95% CI 1.6-31.0, P = 0.010), and a higher agreement with statements regarding concerns about CPVT medication (OR 1.2, 95% CI 1.1-1.3, P < 0.001) were independently associated with non-adherence. The significant rate of non-adherence associated with concerns regarding CPVT-related medication, emphasizes the potential for improving therapy adherence by targeted patient education.

Global Longitudinal Strain May Be the One that Appropriately Identifies Candidates of ICD Implantation.

Hypertrophic cardiomyopathy (HCM) significantly contributes to an elevated risk of sudden cardiac death. Primary prevention is implemented by using an implantable cardioverter defibrillator (ICD). However, all of the HCM patients do not really need ICD therapy. Providing a superior index for ICD indication compared with the current indices like ejection fraction is essential to differentiate high-risk patients efficiently. The present study assessed the potential of global longitudinal strain (GLS) for the differentiation of HCM patients based on their need for ICD shocks. Patients with HCM were considered in four defined centers between March and June 2021. Those with previous ICD implantation or current candidates for ICD therapy were included in the study. Participants were subjected to speckle-tracking echocardiography, and GLS as well as some other echocardiographic parameters were recorded. Afterwards, data from implanted ICDs were extracted. Patients who received ICD shocks (appropriate) due to ventricular tachycardia (VT)/ventricular fibrillation (VF) were categorized in group A. The remaining patients were constituted group B who received inappropriate shocks, i.e., other than VT/VF. Overall, 34 patients were found eligible to participate with a mean age of 62 ± 16.1 years including 64.7% of males. Among a variety of echocardiographic parameters, GLS was the sole one that was significantly higher in group A compared with that in group B. Our findings revealed that only GLS could predict fatal arrhythmias. To substantiate, the odds of VT were raised by 43% with a single increase in GLS unit. GLS showed the highest accuracy for ICD indication among HCM patients and, therefore, could be a solid and early criterion to predict the incidence of life-threatening arrhythmias. In this regard, identifying appropriate HCM patients with respect to their need for ICD therapy is feasible.

Safety and Efficacy of Ultrasound-Guided Sympathetic Blockade by Proximal Intercostal Block in Electrical Storm Patients

BackgroundElectrical storm (ES) patients who fail standard therapies have a high mortality rate. Previous studies report effective management of ES with bedside, ultrasound-guided percutaneous stellate ganglion block (SGB). We report our experience with sympathetic blockade administered via a novel alternative approach: proximal intercostal block (PICB). Compared with SGB, this technique targets an area typically free of other catheters and support devices, and may pose less strict requirements for anticoagulation interruption, along with lower risk of focal neurological side effects. ObjectivesThe authors sought to describe the safety and efficacy of PICB in patients with refractory ES. MethodsWe reviewed our institutional data on ES patients who underwent PICB between January 2018 and February 2023 to analyze procedural safety and short- and long-term outcomes. ResultsA total of 15 consecutive patients with ES underwent PICB during this period. Of those, 11 patients (73.3%) were maintained on PICB alone, and 4 patients (26.6%) were maintained on combined block with SGB and PICB. Overall, 72.7% patients who were maintained on PICB alone and 77.8% patients who were maintained on bilateral PICB had excellent arrhythmia suppression. After PICB, implantable cardioverter-defibrillator therapies were significantly reduced (P < 0.05), with 93.3% of patients receiving PICB having no implantable cardioverter-defibrillator shock until discharge or heart transplant. Anticoagulation was continued in all patients and there were no procedure-related complications. Apart from mild transient neurological symptoms seen in 3 patients, no significant neurological or hemodynamic sequelae were observed. ConclusionsIn patients with refractory ES, continuous PICB provided safe and effective sympathetic block (77.8% ventricular arrhythmia suppression), achievable without interruption of anticoagulation, and without significant side effects.

Outcomes of permanent pacemakers and implantable cardioverter-defibrillators in an adult congenital heart disease population

BackgroundBrady- and tachyarrhythmias commonly complicate adult congenital heart disease (ACHD). Permanent pacemakers (PPMs) or implantable cardioverter–defibrillators (ICDs) are often utilised to prevent morbidity or mortality related to arrhythmia, but can also be associated with significant morbidity themselves. MethodsWe analysed outcomes from patients in our comprehensive ACHD database who were seen at least twice since 2000 and once since 2018. Of 1953 ACHD patients, 134 had a PPM and 78 had an ICD (47 for primary and 31 for secondary prevention). ResultsFor PPM patients, 41% had a pacing percentage below 33%, 13% had 33–66%, and 46% had above 66%. One fifth required PPM upgrade, most to cardiac resynchronisation therapy, the rest to ICD. There were 33 appropriate ICD shocks in 15 patients (19%) and 34 inappropriate shocks in 13 patients (17%) over a median follow up of 4.6 years (IQR 0.9–8.3 years). Anti-tachycardia pacing was delivered appropriately for 28% of patients and inappropriately for 9%.Apart from inappropriate therapy, one third of PPM and ICD patients had other device-related complications. Acute PPM complications included lead dysfunction requiring revision (2%), pneumothorax (2%), pleural effusion (2%) and pocket infection (2%). ICDs were also acutely complicated by lead dysfunction (4%) as well as pocket hematoma (3%). The most common long-term complication overall was lead dysfunction, affecting one sixth of both PPM and ICD patients. Finally, the rate of device insertion increased significantly with disease severity. ConclusionsAnti-arrhythmic devices can be lifesaving in ACHD patients, but inappropriate therapy and device-related complications are very common.

Multiple Implantable Cardioverter-Defibrillator Shocks in Ischemic Cardiomyopathy Compels Coronary Vascularization Reassessment

Abstract The increasing number of patients with heart failure and implantable cardioverter-defibrillators (ICD) has led to a growing of the emergency presentations for ICD internal shocks. Appropriate shocks are sometimes caused by acute events in the course of disease and could be one of the earliest symptoms contributing to the diagnosis and timely treatment of these acute conditions. We present the case of a 64-year-old male patient with ischemic cardiomyopathy, ICD carrier, who presented to the emergency department for recurrent appropriate ICD shocks caused by episodes of polymorphic ventricular tachycardia and ventricular fibrillation. Even if he did not have chest pain, he was referred to cath lab, where the coronary angiography has shown a severe stenosis at the origin of the left anterior descending artery and a moderate stenosis at the proximal left circumflex artery. The percutaneous revascularization of both lesions resulted in the eradication of the sustained ventricular arrhythmias and the improvement of the clinical status. The case argues for the need for coronary vascularization assessment in ICD carrier patients with ischemic heart failure and adequate recurrent shocks, also emphasizing the importance of remote monitoring in early diagnosis of acute conditions in these patients.

Sex-Related Differences in Ventricular Tachyarrhythmia Events in Patients With Implantable Cardioverter-Defibrillator and Prior Ventricular Tachyarrhythmias

BackgroundData on the risk of ventricular tachycardia (VT), ventricular fibrillation (VF), and death by sex in patients with prior VT/VF are limited. ObjectivesThis study aimed to assess sex-related differences in implantable cardioverter-defibrillator (ICD)-treated VT/VF events and death in patients implanted for secondary prevention or primary prevention ICD indications who experienced VT/VF before enrollment in the RAID (Ranolazine Implantable Cardioverter-Defibrillator) trial. MethodsSex-related differences in the first and recurrent VT/VF requiring antitachycardia pacing or ICD shock and death were evaluated in 714 patients. ResultsThere were 124 women (17%) and 590 men observed during a mean follow-up of 26.81 ± 14.52 months. Compared to men, women were at a significantly lower risk of VT/VF/death (HR: 0.67; P = 0.029), VT/VF (HR: 0.68; P = 0.049), VT/VF treated with antitachycardia pacing (HR: 0.59; P = 0.019), and VT/VF treated with ICD shock (HR: 0.54; P = 0.035). The risk of recurrent VT/VF was also significantly lower in women (HR: 0.35; P < 0.001). HR for death was similar to the other endpoints (HR: 0.61; P = 0.162). In comparison to men, women presented with faster VT rates (196 ± 32 beats/min vs 177 ± 30 beats/min, respectively; P = 0.002), and faster shock-requiring VT/VF rates (258 ± 56 beats/min vs 227 ± 57 beats/min, respectively; P = 0.30). There was a significant interaction for the risk of VT/VF by race (P = 0.013) with White women having significantly lower risk than White men (HR: 0.36; P < 0.001), whereas Black women had a similar risk to Black men (HR: 1.06; P = 0.851). ConclusionsWomen with a history of prior VT/VF experienced a lower risk recurrent VT/VF requiring ICD therapy when compared to men. Black Women had a risk similar to men, whereas the lower risk for VT/VF in women was observed primarily in White women. (Ranolazine Implantable Cardioverter-Defibrillator Trial; NCT01215253)

Risk of atrial arrhythmias in patients with ventricular tachycardia in arrhythmogenic right ventricular cardiomyopathy

BackgroundIn arrhythmogenic right ventricular cardiomyopathy (ARVC), risk of atrial arrhythmias (AAs) persists after ventricular tachycardia (VT) ablation. ObjectiveThe purpose of this study was to determine the type, prevalence, outcome, and risk correlates of AA in ARVC in patients undergoing VT ablation. MethodsProspectively collected procedural and clinical data on ARVC patients undergoing VT ablation were analyzed. Risk score for typical atrial flutter was determined from univariate logistic regression analysis. ResultsOf 119 consecutive patients with ARVC and VT ablation, 40 (34%) had AA: atrial fibrillation (AF) in 31, typical isthmus-dependent atrial flutter (AFL) in 27, and atrial tachycardia/atypical flutter (AT) in 10. Seventeen patients (43%) with AA experienced inappropriate defibrillator therapy, with 15 patients experiencing shocks. Ablation was performed for typical AFL in 21 (53%), AT in 5 (13%), and pulmonary vein isolation for AF in 4 (10%) patients and prevented AA in 78% and all AFL during additional mean follow-up of 65 months. Risk score for typical flutter included age >40 years (1 point), ≥moderate right ventricular dysfunction (2 points), ≥moderate tricuspid regurgitation (2 points), ≥moderate right atrial dilation (2 points), and right ventricular volume >250 cc (3points), with score >4 identifying 50% prevalence of typical flutter. ConclusionAAs are common in patients with ARVC and VT, can result in inappropriate implantable cardioverter-defibrillator shocks, and typically are controlled with atrial ablation. A risk score can be used to identify patients at high risk for typical AFL who may be considered for isthmus ablation at the time of VT ablation.

Fragmented QRS complex as a predictor of appropriate shocks in patients undergoing cardiac resynchronization therapy and defibrillator. A chronicle of a shock foretold?

Abstract Introduction Cardiac resynchronization therapy (CRT) has demonstrated to reduce mortality and hospitalization for heart failure in patients with heart failure with reduced ejection fraction (HFrEF) in specific subgroups of patients Moreover, adding an implantable cardioverter defibrillator (ICD) to CRT (CRT-D) has demonstrated to reduce the risk of sudden cardiac death in specific subgroups of patients. However, patients undergoing CRT-D are a very heterogeneous group. In the recent years, several clinical findings, such as fragmentation of the QRS complex (fQRS), have been reported as potential prognostic factors in various cardiac diseases. Nevertheless, the evidence to support the prognostic significance of fQRS in patients undergoing CRT-D remains to be scarce. Purpose The objective of this study is to evaluate if the presence of pre-implantation fQRS predicts appropriate ICD shocks in patients undergoing CRT-D implantation. Methods Consecutive patients undergoing CRT-D implantation were prospectively included from October 2009 to December 2022. Demographic, clinical, electrocardiographic and echocardiographic variables as well as appropriate ICD shock events were collected from electronic clinical records and telephone interview. Fragmentation of the QRS complex was defined by the presence of different RSR′ patterns including an additional R-wave (R′), notching of the R-wave and S-wave or the presence of more than 1R′ in two contiguous leads corresponding to a main coronary artery territory. Results A total of 180 patients were included. Mean age at the device implantation was 69.9 years (standard deviation, SD ±9.6 years), 80.6% were male, 63.8% presented hypertension and 40.0% were diabetic. The aetiology of the LV systolic dysfunction was non-ischaemic in 45.6% of the patients and ischaemic in 54.6%. 43.9% had prior history of acute myocardial infarction, while myocardial scar was described in 45.6% of the patients. Pre-implantation fQRS was found in 61.7% of the patients. Mean LVEF at baseline was 23.6%. The median follow-up time was 34.8 months. At the end of the follow-up, 30.5% patients died. 9.8% of the patients presented appropriate ICD shocks (9.2% in patients with pre-implantation fQRS and 0.6% in patients without pre-implantation fQRS). A multivariate survival analysis using Cox regression showed that presence of pre-implantation fQRS complex was a powerful independent predictor for appropriate ICD shocks (HR 8.36; 95% CI 1.08–64.32). Kaplan-Meier curves for appropriate shocks regarding pre-implantation fQRS status are presented in Figure 1. Conclusions According to our results, pre-implantation fQRS seems to be a strong independent predictor for appropriate ICD shocks after CRT-D implantation. Therefore, these patients could benefit from a more rigorous follow-up as they present higher risk of an arrhythmic event. However, further research is needed to confirm these findings.Figure 1.Kaplan-Meier curves

Long-term outcomes in carriers of the familial idiopathic ventricular fibrillation linked to the DPP6 locus

Abstract Background Idiopathic ventricular fibrillation (IVF) is a malignant condition with no clinical sequelae except for ventricular fibrillation. The genetic basis is ill-defined but in 2009 a Dutch founder variant - the DPP6 risk haplotype - was linked to a familial form of IVF characterized by a very high incidence of sudden cardiac arrest (SCA) and sudden cardiac death (SCD). Consequently, for more than a decade asymptomatic haplotype-carriers from the ages of 18 (male) and 25 (female) have had an implantable cardioverter-defibrillator (ICD) inserted. However, the associated long-term outcomes in these individuals is unknown. Purpose To assess the long-term outcomes of DPP6 risk haplotype-carriers who presented to our tertiary referral center and qualified for ICD insertion. Methods Clinical follow-up information of DPP6 risk haplotype-carriers, including the occurrence of SCD, SCA, appropriate ICD shocks, and ICD-related complications, was collected through February 2023. ICD-carriers were classified as either asymptomatic (primary prevention), or with previous sudden cardiac arrest (secondary prevention). Survival rates are presented using a survival curve and were compared with the log-rank test. Results A total of 118 haplotype-carriers (62 males) were included. One-hundred nine (92%) carriers had an ICD inserted, for primary (n=85) or secondary prevention (n=24), and 9 patients refused a primary prevention ICD. Among primary prevention ICD-carriers and those who refused implantation (n=94), 9 (10%) patients experienced a total of 28 appropriate shocks, there was 1 SCA and no deaths, during a median follow-up of 11 years (IQR 7-13; Figure). Of these, 9 patients were ever treated with quinidine and 5 still used quinidine at last follow-up. Among secondary prevention ICD carriers, 20 (83%) patients experienced a total of 225 appropriate shocks and one patient died, during a median follow-up of 13 years (IQR 10-16). Of these patients, 11 were ever treated with quinidine, of whom one patient discontinued quinidine due to adverse effects. Overall, 14 (13%) patients experienced inappropriate shocks and 16 (15%) experienced other ICD-related complications. Conclusion Predictive genetic testing of the DPP6 haplotype provides the unique opportunity to identify asymptomatic family members at risk for SCD and insert prophylactic ICDs just on the basis of carrying the risk haplotype. Approximately 10% of DPP6 haplotype-carriers who qualified for ICD insertion for primary prevention, predominantly males, experienced appropriate ICD shocks or SCA during 11 years of follow-up, indicating that our approach to ICD implantation has presumably saved several lives. In those with an ICD for secondary prevention the incidence of appropriate ICD shocks was high, often despite quinidine therapy.Survival until appropriate shock or SCA

High-intensity interval training in patients with an implantable cardioverter defibrillator: a randomized controlled study

Abstract Background Exercise is an effective treatment in a broad spectrum of cardiovascular diseases. High-intensity interval training (HIIT) has shown superior effect on cardiorespiratory fitness and equal or superior effect on morbidity and quality of life (QoL) compared to moderate continuous exercise training. However, evidence of the efficacy and risks of HIIT in patients with increased risk of ventricular arrhythmia remains limited. Purpose To evaluate the effects of HIIT on exercise capacity, QoL and burden of ventricular arrhythmias in patients with an implantable cardioverter defibrillator (ICD) with or without cardiac resynchronization therapy. Methods Patients with ischemic or dilated cardiomyopathy and ICD were randomized to a supervised 12-week HIIT program or to a control group continuing their usual exercise routines. HIIT consisted of four 4-minute intervals aiming at 85-95% of maximum heart rate (HRmax), and 3-minute active recovery aiming at 60-70 % of HRmax in between intervals, 3 times a week for 12 weeks. Primary outcomes were exercise capacity measured as peak oxygen uptake (VO2 peak) and QoL assessed with the Short Form 36 (SF-36) questionnaire. Main secondary outcome was the burden of ventricular arrhythmias analysed from remote patient monitoring data. Results Fifty-six patients were included (table 1). Three patients in the HIIT group did not complete the intervention. Two withdrew due to a knee injury and due to fear of SARS-CoV-2 exposure, respectively. One experienced an appropriate shock during exercise and was excluded from further training after clinical consideration. Fifty-three patients completed all follow-up examinations. HIIT significantly increased VO2 peak with 7.0 %, with no changes in the control group (p=0.001) (figure 1A). There was a significant increase in the SF-36 subscale scores on physical functioning (p&amp;lt;0.05), general health (p&amp;lt;0.05) and health change (p=0.001) in the HIIT group compared to the control group (figure 1B). There were no significant differences between groups in number of non-sustained or sustained ventricular tachycardias, anti-tachycardia pacing therapy or ICD shocks. Conclusions In patients with ICD due to ischemic or dilated cardiomyopathy, a supervised 12-week HIIT-program significantly increased VO2 peak and QoL without increasing the burden of ventricular arrhythmias.Table 1:Patient characteristicsFigure 1:Peak oxygen uptake and QoL

Impact of neuromuscular assessment on arrhythmic risk in LMNA cardiomyopathy

Abstract Background The current Risk Score for Life-Threatening Ventricular Tachyarrhythmias (LTVT) in LMNA cardiomyopathy does not consider the frequent association between cardiac and neuromuscular phenotypes as a part of a multisystemic disease. In particular, the prognostic value of tendon retractions (TR) has been recently described. Objectives We aimed to assess the prognostic role of TR in a cohort of probands with LMNA cardiomyopathy undergoing multidisciplinary workup at a referral center. Methods We included 28 probands with LMNA cardiomyopathy undergoing regular, prospective follow-up at a national referral center for laminopathies. All patients underwent extensive baseline characterization, including complete neuromuscular examination and systematic assessment of TR. Indications to implantable cardioverter defibrillators (ICD) for the primary prevention of sudden cardiac death were guideline-based. Patients were clustered in tertiles according to their baseline LMNA-Risk Score. The primary endpoint was the 5-year occurrence of LTVT, namely arrhythmic cardiac death, VF, sustained VT, or appropriate ICD shocks. Results Of the 28 probands with LMNA cardiomyopathy (mean age 33±15 years, 50% males, mean LVEF 55±14 %), neurological assessment identified 14 patients (50%) with TR, including 8 cases with no other signs of neuromuscular involvement. At baseline assessment, the median LMNA-Risk Score was 10% (IQR 6-20%). By 5-year follow-up, 9 patients (32%) met the primary endpoint, including three patients in the lowest tertiles of risk (median LMNA-Risk Score 23, range 6-15%). While other variables showed no remarkable differences between groups, the prevalence of TR was 78% among cases experiencing LTVT and 37% otherwise. The presence of either baseline LMNA-Risk score at the highest tertile (&amp;gt;17%) or TR was 100% predictive of 5-year LTVT (9/9 vs. 7/19, p=0.003). Results did not change after reassessment by the end of follow-up (15±5 years). Conclusions Our preliminary data suggest that the inclusion of TR in risk stratification may result in a better patient selection for primary prevention ICD implant in LMNA cardiomyopathy.