Risk stratification and prevention of sudden death in hypertrophic cardiomyopathy

Opinion statement Sudden cardiac death is the most devastating manifestation of hypertrophic cardiomyopathy (HCM) and often occurs in young and previously asymptomatic patients. Therefore, risk stratification for sudden death has a major role in the management of HCM and has acquired even greater relevance since the implantable cardioverter-defibrillator (ICD) has proved to be highly effective in preventing sudden death in this disease. The ICD is definitely indicated for secondary prevention of sudden death in patients with HCM who have survived a cardiac arrest with documented ventricular fibrillation, or experienced one or more episodes of sustained ventricular tachycardia. However, uncertainties persist regarding the precise selection of patients for primary prophylactic ICD implantation. A number of risk markers are used to assess the magnitude of risk, including family history of premature sudden death; extreme left ventricular (LV) hypertrophy (> 30 mm) in young patients; nonsustained ventricular tachycardia on Holter electrocardiographic recording; unexplained (not neurally mediated) syncope, particularly in young patients; and blood pressure decrease or inadequate increase during upright exercise. Multiple risk factors convey a definite increase in risk. However, a single risk factor such as family history of multiple sudden deaths, massive LV hypertrophy in a young patient, or frequent and/or prolonged runs of nonsustained ventricular tachycardia on Holter, may also justify consideration of a prophylactic ICD.     

Shock occurrence and survival in 49 patients with idiopathic dilated cardiomyopathy and an implantable cardioverter-defibrillator

To determine shock occurrence and survival, 49 patients withidiopathic dilated cardiomyopathy presenting with cardiac arrest(82%), syncope (12%) or ventricular tachycardia without syncope(6%) were followed for 28 ±28 months after cardioverter-defibrillator(ICD) implant according to the intention to treat principle.Using the Kaplan-Meier method, the actuarial incidence for anyspontaneous shocks was 20%, 58%, and 77%, and the incidenceof appropriate shocks was 16%, 49%, and 72% at 1, 3, and 5 yearsof follow-up, respectively. Only two of 49 study patients (4%)with an active ICD died suddenly during follow-up. Another twopatients, however, with an inactive device died suddenly, resultingin a sudden death rate of 2% per year with an active ICD, and5% per year, according to the intention to treat principle.The incidence of cardiac death from any cause was 8%, 25%, and35%, and the incidence of total mortality was 14%, 39%, and49% during 1, 3, and 5 years of follow-up, respectively. Therewas no difference in the Kaplan-Meier survival curves for shockedvs non-shocked patients. Thus, in this selected patient populationwith idiopathic dilated cardiomyopathy the majority of patientsreceived ‘appropriate’ shocks during follow-up,and the sudden death rate with active ICD is low.     

Implantable Cardioverter-Defibrillators in Children and Adolescents With Brugada Syndrome

Background

Young patients presenting with symptomatic Brugada syndrome have very high risks for ventricular arrhythmias and should be carefully considered for implantable cardioverter-defibrillator (ICD) placement. However, this therapy is associated with high rates of inappropriate shocks and device-related complications.

Efficacy and safety of celivarone,with amiodarone as calibrator,in patients with an implantable cardioverter-defibrillator for prevention of implantable cardioverter-defibrillator interventions or death

Background Celivarone is a new antiarrhythmic agent developed for the treatment of ventricular arrhythmias.This study investigated the efficacy and safety of celivarone in preventing implantable cardioverter-defibrillator (ICD) interventions or death.Methods and Results Celivarone (50,100,or 300 mg /d) was assessed compared with placebo in this randomized,double-blind,placebo-controlled,parallel-group study.Amiodarone (200 mg /d after loading dose of 600 mg /d for 10 days) was used as a calibrator.A total of 486 patients with a left ventricular ejection fraction ≤ 40% and at least 1 ICD intervention for ventricular tachycardia or ventricular fibrillation in the previous month or ICD implantation in the previous month for documented ventricular tachycardia /ventricular fibrillation were randomized.Median treatment duration was 9 months.The primary efficacy end point was occurrence of ventricular tachycardia /ventricular fibrillation-triggered ICD interventions (shocks or antitachycardia pacing) or sudden death.The proportion of patients experiencing an appropriate ICD intervention or sudden death was 61.5 % in the placebo group;67.0 %,58.8%,and 54.9 % in the celivarone 50-,100-,and 300-mg groups,respectively;and 45.3 % in the amiodarone group.Hazard ratios versus placebo for the primary end point ranged from 0.860 for celivarone 300 mg to 1.199 for celivarone 50 mg.None of the comparisons versus placebo were statistically significant.Celivarone had an acceptable safety profile.Conclusions Celivarone was not effective for the prevention of ICD interventions or sudden death.     

Electrophysiologic testing and follow-up of patients with aborted sudden death

Clinical, electrophysiologic and follow-up data were analyzed for 108 patients with aborted sudden death. The mean follow-up interval was 2 years. All patients underwent baseline drug-free invasive electrophysiologic studies. Seventy-five patients (group I) had inducible ventricular arrhythmias (including nonsustained and sustained ventricular tachycardia and ventricular fibrillation) and 33 patients (group II) had no inducible arrhythmias. Noninducibility was not predictive of a favorable outcome, because the incidence of both sudden death and recurrent ventricular tachycardia was similar in the two groups. Treatment guided by electrophysiologic testing was used in 17 patients; in 13 (17%) in group I arrhythmias became noninducible, and in 4 (5%) sustained ventricular arrhythmias became nonsustained after administration of conventional drugs. There was a significantly higher incidence of sudden death and recurrent ventricular tachycardia in the 4 patients with inducible arrhythmias (n = 3, 75%) compared with the 13 patients whose arrhythmias were noninducible (n = 2, 15%) (p less than 0.05). For the group as a whole, 11% died suddenly and 15% had recurrence of ventricular tachycardia. Sixty-four patients were treated with amiodarone and, of these, four (6%) died suddenly during the follow-up period and nine (14%) had recurrent ventricular tachycardia. Ventricular arrhythmias could be induced in 69% of patients with aborted sudden death but inducibility could be suppressed in only 20% of them. The role of therapy guided by electrophysiologic testing could therefore not be fully assessed. The findings reveal a significant recurrence rate of symptomatic, potentially life-threatening ventricular arrhythmias in medically treated patients with aborted sudden death.(ABSTRACT TRUNCATED AT 250 WORDS)     

Survival after cardiac arrest or sustained ventricular tachycardia in patients with hypertrophic cardiomyopathy.

OBJECTIVES: The aim of this study was to evaluate the survival of patients with hypertrophic cardiomyopathy (HCM) after resuscitated ventricular fibrillation or syncopal sustained ventricular tachycardia (VT/VF) when treated with low dose amiodarone or implantable cardioverter defibrillators (ICDs). BACKGROUND: Prospective data on clinical outcome in patients with HCM who survive a cardiac arrest are limited, but studies conducted before the widespread use of amiodarone and/or ICD therapy suggest that over a third die within seven years from sudden cardiac death or progressive heart failure. METHODS: Sixteen HCM patients with a history of VT/VF (nine male, age at VT/VF 19 +/- 8 years [range 10 to 36]) were studied. Syncopal sustained ventricular tachycardia/ventricular fibrillation occurred during or immediately after exertion in eight patients and was the initial presentation in eight. One patient had disabling neurologic deficit after VT/VF. Before VT/VF, two patients had angina, four had syncope and six had a family history of premature sudden cardiac death. After VT/VF all patients were in New York Heart Association class I or II, three had nonsustained VT during ambulatory electrocardiography and 11 had an abnormal exercise blood pressure response. After VT/VF eight patients were treated with low dose amiodarone and six received an ICD. Prophylactic therapy was declined by two patients. RESULTS: Mean follow-up was 6.1 +/- 4.0 years (range 0.5 to 14.5). Cumulative survival (death or ICD discharge) for the entire cohort was 59% at five years (95% confidence interval: 33% to 84%). Thirteen (81%) patients were alive at last follow-up. Two patients died suddenly while taking low dose amiodarone, and one died due to neurologic complications of his initial cardiac arrest. Three patients had one or more appropriate ICD discharges during follow-up; the times to first shock after ICD implantation were 23, 197 and 1,124 days. CONCLUSIONS: This study shows that patients with HCM who survive an episode of VT/VF remain at risk for a recurrent event. Implantable cardioverter defibrillator therapy appears to offer the best potential benefit regarding outcome.     

Ventricular arrhythmias in congestive heart failure: clinical significance and management

The benefit of defibrillator therapy has been well established for patients with LV dysfunction (ejection fraction less than 35%), coronary artery disease, NSVT, and inducible and nonsuppressible ventricular tachycardia. Implantable cardioverter-defibrillator therapy is also indicated for all CHF patients in NYHA functional classes I, II, and III who present with aborted sudden cardiac death, or ventricular fibrillation, or hemodynamically unstable ventricular tachycardia--and also in patients with syncope with no documented ventricular tachycardia but with inducible ventricular tachycardia at electrophysiology study. The ongoing MADIT II trial was designed to evaluate the benefit of prophylactic ICD implantation in these patients (ejection fraction less than 30%, coronary artery disease, and NSVT) without prior risk stratification by PES. The CABG Patch trial concluded that prophylactic placement of an ICD during coronary artery bypass grafting in patients with low ejection fraction and abnormal SAECG is not justifiable. Except for the indications described above, ICD implantation has not been proved to be beneficial as primary or secondary therapy. Until more data are available, patients should be encouraged to enroll in the ongoing clinical trials.     

Implantable defibrillators and prevention of sudden death in hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is the most common cause of sudden cardiac death in young people, including trained athletes. The implantable cardioverter-defibrillator (ICD), although initially designed as a treatment for older patients with coronary artery disease, has more recently proved to be a safe and effective therapeutic intervention in young patients with HCM, both for primary or secondary prevention of sudden death. The largest such report of >500 patients showed that the ICD intervened appropriately to abort ventricular tachycardia/fibrillation (VT/VF) in 20% of patients over an average follow-up period of only 3.7 years, at a rate of about 4% per year in those patients implanted prophylactically, and often with considerable delays of up to 10 years. Extensive experience with high-risk HCM patients showed that appropriate device discharges for VT/VF occur with similar frequency in patients with 1, 2, or > or = 3 noninvasive risk markers. Despite the extreme morphology characteristic of HCM, often with massive degrees of left ventricular (LV) hypertrophy and/or LV outflow tract obstruction, ICDs performed in a highly effective fashion, with failure to convert life-threatening arrhythmias extraordinarily rare. In conclusion, in a large high-risk HCM cohort, ICD interventions for life-threatening ventricular tachyarrhythmias were frequent and highly effective in restoring normal rhythm. An important proportion of ICD discharges occurred in primary prevention patients with only one risk factor. Therefore, a single marker of high risk may represent sufficient evidence to justify the recommendation for a prophylactic ICD in selected patients with HCM.     

Catheter ablation of ventricular tachycardia in ischaemic and non-ischaemic cardiomyopathy: where are we today? A clinical review

According to the current guidelines, patients with ischaemic cardiomyopathy (ICM) or non-ischaemic cardiomyopathy (NICM) at risk for sudden cardiac death should undergo implantation of an implantable cardioverter-defibrillator (ICD). Although ICDs effectively terminate ventricular arrhythmias, the arrhythmogenic substrate remains unchanged or may progress over time, resulting in recurrent ICD shocks. Defibrillator shocks increase mortality and worsen quality of life. Evidence from two prospective randomized trials on outcome in patients with ischaemic heart disease undergoing catheter ablation for ventricular tachycardia (VT) suggests that ablation prevents recurrence of VT and decreases the number of ICD shocks. This review will highlight the recent progress made in the ablative treatment of VT in patients with ICM and NICM.     

Ventricular Fibrillation and Polymorphic Ventricular Tachycardia with Critical Coronary Artery Stenosis:

ICD Therapy and CABG for Sudden Death. Introduction: Previous studies have suggested that coronary artery bypass surgery is sufficient to prevent recurrence of sudden death in patients with critical coronary artery stenosis presenting with ventricular fibrillation or polymorphic ventricular tachycardia. We present our experience in patients with one or more episodes of sudden death associated with documented ventricular fibrillation or polymorphic ventricular tachycardia and severe operable coronary artery disease who underwent defibrillator implant at the time of bypass surgery. Methods and Results: Fifty-eight consecutive patients (age 63 ± 8 years) were included in this study. Eighteen of the 58 patients had no evidence of previous myocardial infarction. The mean ejection fraction was 37 ± 13%. All patients underwent electrophysiologic study before and after revascularization. At the time of first defibrillator discharge, each patient was reevaluated to exclude the presence of ischemia. The benefits of defibrillator implant were estimated comparing the projected survival based upon defibrillator discharge preceded by syncope or presyncope with survival curves generated including total death and sudden plus cardiac death. After a mean follow-up of 4.6 ± 2 years, 22 patients received appropriate shocks preceded by syncope or presyncope, and an additional 19 patients received asymptomatic shocks. At 4 years, survival free of total death was 71.2%, and the projected survival was 58.8% (P < 0.05). Multivariate analysis showed that ejection fraction lower than 30% and induction of arrhythmia with one or two extrastimuii (S2, S3) were independent predictors for defibrillator discharge. None of the remaining variables including age, gender, number of bypasses, history of myocardial infarction, and type of arrhythmias induced were predictive for death and occurrence of shocks. Conclusions: In patients with ventricular fibrillation and polymorphic ventricular tachycardia, bypass surgery does not protect from recurrence of life-threatening arrhythmias, and, as in our population, defibrillator implant may have significant impact on survival.     

Outcome after implantable cardioverter-defibrillator in patients with Brugada syndrome: the Gulf Brugada syndrome registry

Background and ObjectiveAmong patients with Brugada syndrome (BS) and aborted cardiac arrest, syncope, or inducible ventricular fibrillation at electrophysiologic study (EPS), the only currently recommended therapy is an implantable cardioverter-defibrillator (ICD), but these are not without complications. We assessed the total number of shocks (appropriate and inappropriate) and complications related to ICD in patients with BS.Methods and ResultsTwenty-five patients implanted with ICD for BS in 6 Gulf centers between January 1, 2002, and December 31, 2010, were reviewed. Implantable cardioverter-defibrillator indication was based on aborted cardiac arrest (24%), syncope (56%), or in asymptomatic patients with positive EPS (20%). During a follow-up of 41.2 ± 17.6 months, 3 patients (all with prior cardiac arrest) had appropriate device therapy. Four patients developed complications; 3 of them had inappropriate shocks.ConclusionIn our cohort, appropriate device therapy was limited to cardiac arrest survivors, whereas none of those with syncope and/or positive EPS had arrhythmias. Overall complication rate was relatively high, including inappropriate ICD shocks.     

肥厚型心肌病猝死预防:肥厚型心肌病患者除颤器置入

Hypertrophic cardiomyopathy (HCM) is the most common cause of sudden cardiac death in young people. The implantable cardioverter-defibrillator (ICD), has recently proved to be a safe and effective therapeutic intervention in patients with HCM, both for the primary and secondary prevention of sudden death. Based on recent substantial experience, the ICD intervenes appropriately to termiante ventricular tachycardia/fibrillation (VT/VF), at a rate of 5.5%/year. ICD discharge rate is 4%/year in those patients implanted prophylactically due to one or more major risk markers, but often with considerable delays of up to 10 years before the device is required to intervene appropriately to terminate potentially letal ventricular tachyarrhythmias. Primary prevention of VT/VF occurs with similar frequency in high-risk patients having either 1,2 or ≥ 3 noninvasive risk markers, and about one-third of patients with appropriate device interventions had been implanted for only one risk factor. The ICD has proved reliable in HCM despite the extreme and complex phenotypes often present with massive degrees of left vcntricular hypertrophy, microvascular ischemia, diastolic dysfunction, or dynamic left ventricular outflow tract obstruction. Failure to convert life-threatening ventrieular tachyarrhythmias to normal rhythm is extraordinarily rare. In conclusion, in high-risk HCM patients, ICDs perform in a highly effective fashion,frequently preventing sudden death by aborting primary life-threatening ventricular tachyarrhythmias. A single marker of high risk can be sufficient evidence to justify the recommendation for a prophylactic ICD in selected patients with HCM.     

Automatic implantable cardioverter-defibrillator implantation without thoracotomy using an endocardial and submuscular patch system

The automatic cardioverter-defibrillator lead system is implanted by a thoracotomy procedure that may result in atelectasis, pleural effusion, cardiac tamponade and lengthy convalescence. A new defibrillator lead system that allows selection of different defibrillating current pathways is implanted without a thoracotomy. Ten patients requiring a cardioverter-defibrillator for recurrent sustained ventricular tachycardia (five patients) or aborted sudden cardiac death (five patients) were evaluated for implantation of this lead system. A lead configuration with a bidirectional defibrillating current pathway was implanted in nine patients. The defibrillation threshold with this lead configuration was 15 J in five patients, 20 J in three and 30 to 35 J in one patient. In the remaining patient the lead system had a 40 J defibrillation threshold and was not implanted. No perioperative complications occurred. Induced ventricular fibrillation was successfully terminated at the predischarge and intermediate follow-up (8 to 12 weeks) electrophysiologic studies. During the follow-up period, there were three deaths (one sudden, two due to heart failure) and two lead system failures (oversensing with inappropriate shocks in one patient and patch lead fracture in another). Implantation of the cardioverter-defibrillator lead system by a nonthoracotomy approach is feasible, has no significant perioperative complications and is well tolerated by patients. Effective defibrillation was demonstrated immediately as well as at intermediate follow-up study. The occurrence of patch lead fracture and oversensing requires improvement in the present (nonthoracotomy) lead system technology.     

Electrophysiologic manifestations of ventricular tachyarrhythmias provoking appropriate defibrillator interventions in high-risk patients with hypertrophic cardiomyopathy

Introduction: Our objective was to determine features of ventricular tachyarrhythmias triggering appropriate implantable cardioverter-defibrillator (ICD) interventions in hypertrophic cardiomyopathy (HCM).
Methods and Results: The study cohort was 68 high-risk HCM patients who received ICDs for primary sudden cardiac death prevention from 1995 to 2003. All episodes of sustained ventricular tachyarrhythmias identified by stored intracardiac electrograms were analyzed. Nine patients had 51 episodes of sustained ventricular tachyarrhythmic events that required device therapy (mean follow-up, 3.4 ± 2.2 years; cumulative event rate, 3.2% per year): five had 47 episodes of monomorphic ventricular tachycardia (VT); four each had one episode of ventricular fibrillation (VF). Sinus tachycardia or atrial fibrillation was the initiating rhythm in five of nine patients and in 43 of 51 episodes of events. Of the 17 episodes of monomorphic VT detected in the VT zone, 16 (94%) were terminated by antitachycardia pacing. Thirty episodes of monomorphic VT were detected in the VF zone and were terminated by defibrillation.
Conclusion: Sustained monomorphic VT is common in a high-risk cohort with HCM. Sinus tachycardia is often the initiating rhythm, suggesting that high sympathetic drive may be proarrhythmic when a susceptible substrate is present. Antitachycardia pacing is highly effective in terminating VT in this patient population.     

Importance of ventricular tachycardia storms not terminated by implantable cardioverter defibrillators shocks in patients with CASQ2 associated catecholaminergic polymorphic ventricular tachycardia

In this study, the clinical and implantable cardioverter-defibrillator (ICD)-related follow-up of patients with catecholaminergic polymorphic ventricular tachycardia (CPVT) with homogenous missense mutations in CASQ2 was summarized. Patients were followed in a pediatric cardiology clinic and an ICD clinic. All patients were treated with high-dose β blockers. ICDs were recommended for patients who remained symptomatic despite medical treatment. Twenty-seven patients were followed for 1 to 15 years (median 9). Twenty patients (74%) were symptomatic at diagnosis; 13 (65%) remained symptomatic after treatment with high-dose β blockers and thus were advised to receive ICDs. Eight of these patients refused ICDs, and eventually 6 (75%) died suddenly. Four of the 5 patients who received ICDs had ventricular tachycardia storms treated but not terminated by recurrent ICD shocks. These ventricular tachycardia storms (2 episodes in 2 patients and 1 episode in 2 patient) terminated spontaneously after finishing the programmed ICD shocks, without degeneration to ventricular fibrillation. None of the patients who received ICDs died. In conclusion, patients with CASQ2-associated CPVT should be recommended to receive ICDs to prevent sudden death when medical therapy is not effective. These patients may have recurrent ventricular tachycardia storms treated but not terminated by recurrent ICD shocks, without degeneration to ventricular fibrillation.     

肥厚型心肌病猝死危险因素分层

The natural history of hypertrophic cardiomyopathy(HCM)is extremely heterogeneous.Many patients remain asymptomatic throughout life,some develop severe symptoms of heart failure,but others die suddenly.often in the absence of previous symptoms and at a young age.Therefore,identification of those patients at high risk of sudden death represents a major clinical problem and has become an even greater challenge since the implantable cardioverter-defibrillator(ICD)has proved to be highly effective in preventing sudden death in HCM.Patients who have survived a cardiac arrest,or one or more episodes of sustained ventricular tachycardia,are considered to be at high risk and are candidates for an ICD.However,this patient subset represents a small proportion of the HCM population.The greatest difficulty concerns the identification of high risk patients who are candidates for primary prevention of sudden death with a prophylactic ICD.Decisions are based on generally accepted clinical markers which are associated with increased risk,including:family history of sudden death,extreme left ventricular(LV)wall thickness(≥30 mm),nonsustained ventricular tachycardia on Holter monitoring,unexplained(non-neurocardiogenic)syncope particularly in young patients,and hypotensive blood pressure response to exercise.Patients with end-stage HCM or a LV apical aneurysm represent important arrhythmogenic subsets also associated with substantially increased risk.Multiple or single strong risk markers are associated with increased sudden death risk and iustify consideration for a prophylactic ICD.     

Myocardial Fibrosis Severity on Cardiac Magnetic Resonance Imaging Predicts Sustained Arrhythmic Events in Hypertrophic Cardiomyopathy

Background

The purpose of our study was to correlate the incidence of adequate implantable cardioverter-defibrillator (ICD) interventions in hypertrophic cardiomyopathy (HCM) patients with risk markers (RMs) for sudden cardiac death (SCD) plus myocardial fibrosis as detected by late gadolinium-enhanced cardiac magnetic resonance (LGE-CMR) imaging.

Methods

In all, 87 patients with HCM underwent LGE-CMR imaging prior to ICD implantation, performed for secondary (n = 2; 2%) or primary SCD prophylaxis (n = 85; 98%). Fibrosis was graded with a 17-segment left ventricular model (0 = absent, 1 = point-shaped, 2 = limited to 1 left ventricular segment, 3 = involving ≥ 2 segments). During follow-up, ICD memories were read out by a physician blinded to the individual patient data.

Results

The number of RMs per patient was 1.9 ± 0.8. Myocardial fibrosis was present in 78 patients (90%); 26 (30%) had a fibrosis score of 3. During follow-up (3.5 ± 2.6 [range, 0.2-11.4 years]), 15 patients had 50 appropriate ICD interventions. Episodes of atrial fibrillation were found in 28 patients. Fibrosis severity correlated with occurrence of ventricular tachycardia (Cramér's V, or φc = 0.4, P < 0.001) and atrial fibrillation (φc = 0.6, P < 0.001). On multivariate regression analysis, an independent association between myocardial fibrosis (ß = 0.6, P < 0.01) and sustained ventricular tachycardia was found.

Conclusions

In HCM patients treated with ICD implantation because of a high SCD risk by traditional RM assessment, a high rate of arrhythmic events was observed during long-term follow-up. In a cohort of patients with clinical markers for high risk of SCD, severity of myocardial fibrosis as detected by an easy LGE-CMR scoring system was associated with future arrhythmic events and appropriate ICD therapies.     

Frequent ICD Shocks due to Double Sensing in Patients with Bi-Ventricular Implantable Cardioverter Defibrillators

Biventricular pacing has emerged as a modality for treatment of patients with heart failure. Combined biventricular pacers and implantable cardioverter defibrillators offer treatment of heart failure as well as protection from sudden cardiac death. However, inappropriate ICD shocks as a result of double sensing due to widely spaced ventricular bipoles may pose a significant problem in these patients.We examined the ICD records of twenty-three patients with biventricular ICDs, and evaluated all episodes of double sensing that resulted in aborted or delivered therapy.In follow-up of 3.7 ± 2.6 months, thirty-three shocks in fifteen episodes occurred in five patients (21.7%) due to double sensing. Four patients (17.4%) had aborted shocks due to double sensing. All episodes resulting in shock occurred because of sinus tachycardia or supraventricular tachycardia above the upper programmed pacing rate of the device with resultant AV conduction and double sensing of the nonpaced ventricular depolarization.In conclusion, double sensing of the R-wave is a common and clinically important cause of inappropriate ICD detection and shock in patients with biventricular ICDs. Appropriate programming of the ICD can prevent episodes of inappropriate shocks.     

Ventricular tachycardia in arrhythmogenic right ventricular dysplasia/cardiomyopathy: clinical presentation, risk stratification and results of long-term follow-up

BACKGROUND: Not all patients with arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C) are at risk for sudden cardiac death. The aim of the study was to evaluate the risk stratification in patients with ARVD/C. METHODS AND RESULTS: Programmed ventricular stimulation (PVS) was performed in 34 ARVD/C patients. Twenty-two, 7 and 4 patients had documented sustained monomorphic ventricular tachycardia (smVT), non-smVT and ventricular fibrillation, respectively. One patient experienced syncope only. An implantable cardioverter defibrillator (ICD) was implanted in 11 patients inducible in smVT with hemodynamic compromise, in 4 patients with documented ventricular fibrillation and in one patient with non-smVT (194 ms tachycardia cycle length) (ICD group, n = 16). Ten patients were left without any antiarrhythmic therapy, 5 patients received antiarrhythmic drugs and 3 patients underwent successful VT ablation (non-ICD group, n = 18). Thirteen patients had an abnormal signal averaged ECG. During 6.5 +/- 2.4 years 69% of ICD patients received appropriate discharges and one non-ICD patient had a hemodynamically tolerated smVT recurrence (no sudden cardiac death in both groups). Comparison between the cycle lengths of clinical VT, induced VT and follow-up VT revealed a strong relationship (R = 0.62-0.88). On multivariate analysis abnormal signal averaged ECG and decreased left ventricular ejection fraction were statistically significant predictors for VT recurrence. CONCLUSIONS: In ARVD/C the tachycardia cycle length of clinical VT, PVS-induced VT and follow-up VT correlate well implicating that a PVS-guided approach does not provide additional information. Spontaneous arrhythmia in combination with clinical presentation allows identification of patients in need for an ICD.     

Catheter Ablation of Ventricular Arrhythmia in Patients With an Implantable Cardioverter-Defibrillator: A Systematic Review and Meta-analysis

BackgroundImplantable cardioverter-defibrillator (ICD) shocks are associated with higher rates of mortality and reduced quality of life. In this study we aimed to investigate the effectiveness of catheter ablation (CA) of ventricular tachycardia in patients with an ICD.MethodsAn electronic literature search was conducted to identify randomized controlled trials that compared CA vs control. The primary outcomes were recurrence of ventricular arrhythmia (ventricular tachycardia or ventricular fibrillation) and mortality. Kaplan–Meier curves for these outcomes were digitized to obtain individual patient data, which were pooled in a 1-stage meta-analysis to determine hazard ratios (HRs) and 95% confidence intervals (CIs). Secondary outcomes included cardiac hospitalization, electrical storm, syncope, appropriate ICD therapies, appropriate ICD shocks, and inappropriate shocks. For these, study-level HRs or risk ratios were obtained and pooled in random effects meta-analyses. Subgroup analysis was performed for trials that investigated prophylactic CA (before or during ICD implantation).ResultsData on 9 studies and 1103 patients were retrieved. CA significantly reduced ventricular tachycardia/ventricular fibrillation recurrence compared with control (shared frailty HR, 0.63; 95% CI, 0.49-0.81; P < 0.001) but not mortality (shared frailty HR, 0.84; 95% CI, 0.57-1.23; P = 0.361). CA was associated with significantly lower rates of cardiac hospitalization, electrical storm, appropriate ICD therapies and shocks, but not syncope or inappropriate shocks. Subgroup analysis showed similar results for prophylactic CA except that no significant difference was observed for cardiac hospitalizations.ConclusionsCA is associated with reduced ventricular arrhythmia recurrence, appropriate ICD therapies/shocks, electrical storm, and cardiac hospitalization, and might be effective in preventing future morbidity. Future trials are needed to support the continued benefit of these promising results, and to investigate the optimal timing of ablation.