Implantable cardioverter defibrillator therapy in patients with arrhythmogenic right ventricular cardiomyopathy, long QT syndrome, or no structural heart disease

The Value of Strain Echocardiography in Predicting Electrical Progression in Patients With Arrhythmogenic Right Ventricular Cardiomyopathy

BACKGROUND

Arrhythmogenic right ventricular (RV) cardiomyopathy is a progressive disease characterized by the replacement of the normal myocardium with fibrofatty tissue. This study aimed to determine the value of echocardiographic RV deformation parameters in predicting electrical progression as assessed by serial changes in RV lead sensing and threshold in patients with arrhythmogenic RV cardiomyopathy.

METHODS

The present study recruited 40 patients with a definitive diagnosis of arrhythmogenic RV cardiomyopathy at a mean (SD) age of 38.6 (14.2) years between 2018 and 2020. All patients had received an implantable cardioverter-defibrillator for the primary or secondary prevention of sudden cardiac death. The patients underwent 2-dimensional (2D) and 3-dimensional (3D) transthoracic echocardiographic examinations and RV 2D and 3D strain analyses, comprising free-wall longitudinal strain, global longitudinal strain, and strain rate. They were then followed up for electrical progression.

RESULTS

During a mean (SD) follow-up period of 20 (6) months, the RV lead amplitude decreased from 7.95 (IQR, 4.53-10.25) mV to 5.25 (IQR, 2.88-8.55) mV (P < .001), and the lead threshold increased from 0.75 (IQR, 0.50-0.79) V to 0.75 (IQR, 0.75-1.00) V (P < .001). Right ventricular 2D free-wall (ρ = 0.56, P = .01), RV 2D global (ρ = 0.58, P = .007), and RV 3D free-wall (ρ = 0.65; P = .003) longitudinal strain correlated with electrical progression.

CONCLUSION

Right ventricular 2D and 3D deformation parameters were found to be significant predictors of electrical progression during follow-up of patients with arrhythmogenic RV cardiomyopathy. These findings suggest that echocardiography has a pivotal role in predicting patients at high risk for electrical progression.

Radial and Circumferential CMR-Based RV Strain Predicts Low R Wave Amplitude after ICD Implantation in Patients with Arrhythmogenic Cardiomyopathy

Inadequate R wave amplitude (RWA) after implantable cardiac defibrillator (ICD) implantation in patients with arrhythmogenic cardiomyopathy (ACM) was suspected to relate to right ventricle impairment. However, little data-based evidence was provided to quantify the association. We retrospectively enrolled ACM patients receiving CMR examinations before transvenous ICD implantation from Fuwai Hospital. The RWA was obtained within 24 h and at 2-6-month follow-up after the operation. Structural, functional, as well as tissue characterization of the left ventricle (LV) and right ventricle (RV), were analyzed in relation to RWA. Among the 87 ACM patients (median RWA: 8.0 mV), 19 (21.8%) patients were found with low initial RWA (<5 mV) despite attempts in multiple positions. RV end diastolic diameter (RVEDD), (r = -0.44), RV ejection fraction (RVEF, r = 0.43), RV end diastolic volume index (RVEDVi, r = -0.49), RV end systolic volume index (RVESVi, r = -0.53), RV global circumferential (RVGCS, r = -0.64), and radial strain (RVGRS, r = 0.61, all p < 0.001) rather than LV metrics correlated strongly with initial RWA. RVGCS, RVESVi, and RVGRS were decent predictors of low RWA (areas under the curve AUC: 0.814, 0.769, 0.757, respectively) early after implantation and during 2-6-month follow-up. To summarize, low RWA of ICD lead in ACM patients was associated with RV abnormalities. The RVGCS, RVGRS, and RVESVi can be valuable predictors for identifying low RWA prior to ICD implantation.

Pharmacotherapy and other therapeutic modalities for managing Arrhythmogenic Right Ventricular Cardiomyopathy

Arrhythmogenic Right Ventricular Cardiomyopathy (ARVC) is a genetically determined rare cardiomyopathy (1 in 5000 to 1 in 2000 in the general population), which can lead to ventricular arrhythmias and sudden death (SD). The classic form of the disease has a predilection for the right ventricle (RV), but recognition of left-dominant and biventricular variants led to the broader term "Arrhythmogenic Cardiomyopathy". The disease affects men more frequently than women and becomes clinically overt usually from the second to the fourth decade of life. Treatment consists of restriction of physical exercise, antiarrhythmic drugs, catheter ablation and ICD implantation. These treatments have the potential to change the natural history of the disease by protecting against SD and offering a good-quality and nearly normal life-expectancy. Antiarrhythmic drugs play an important role in terms of reduction of both the number and the complexity of arrhythmias, but they do not reduce the risk of SD. The results of catheter ablation are poor because of the high rate of VT recurrence. ICD should be reserved to selected patients after an accurate risk stratification. The clinical challenge is to improve risk stratification for better identification of those patients who most benefit from the above therapies. Unfortunately, a curative therapy is not yet available.

Treatment of Arrhythmogenic Right Ventricular Cardiomyopathy/Dysplasia: An International Task Force Consensus Statement

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Implantable cardioverter-defibrillators in patients with arrhythmogenic right ventricular cardiomyopathy: the course of electronic parameters, clinical features, and complications during long-term follow-up

PURPOSE

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a progressive cardiomyopathy characterized by myocardial atrophy and fibro-fatty replacement of the right ventricle (RV) and ventricular tachyarrhythmias in young patients. Our aim was to evaluate clinical course and electronic parameters in patients with implantable cardioverter-defibrillator (ICD) and ARVC, during long-term follow-up.

METHODS AND RESULTS

We report on 12 patients with ARVC (mean age 40 ± 13 years) who were treated with ICD implantation in our center. Although several RV sites were tested for proper lead positions, the amplitude of R-wave at implantation was quite low (7.4 ± 3.0 mV). After a mean follow-up of 91 ± 28 months, R-wave amplitude significantly decreased to a mean value of 5.4 ± 2.5 mV (p=0.03). We also found a noticeable, nearly significant increase in pacing threshold (p=0.052) and a moderate increase in defibrillation impedance (p=0.07). Six patients (46 %) experienced at least one appropriate ICD therapy; three patients (23 %) experienced inappropriate ICD shocks secondary to the supraventricular tachycardia, T-wave oversensing, and electromagnetic interference.

CONCLUSIONS

ICD in patients with ARVC has been demonstrated to be feasible and safe. In our case series, we found low R-wave amplitudes at implantation and a significant R-wave decrease during follow-up; a considerable and nearly significant increase in pacing threshold was also observed. These findings may be related to the progressive fibro-fatty replacement of RV myocardium. Multiple sites should be tested in the right ventricle if sensing or pacing values are not optimal, and all the electronic parameters should be carefully monitored throughout the entire follow-up.

Risk stratification in arrhythmogenic right ventricular cardiomyopathy

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a genetic cardiomyopathy characterized by myocyte death and fibrofatty replacement mostly in the right ventricle. It is a leading cause of sudden cardiac death (SCD) in individuals under the age of 35 years. The main goal in the treatment of the disease is the prevention of SCD. An implantable cardioverter-defibrillator (ICD) is the only proven life-saving therapeutic option able to improve survival in ARVC patients. This therapy is not free from side effects and it accounts for a relatively high rate of morbidity because of the occurrence of inappropriate ICD interventions and of complications, both at implantation and during the follow-up. In recent years, the approach to ICD implantation has been changing on the basis of new emerging data on risk stratification. The usefulness of ICD implantation for secondary prevention has been definitively proven; the most challenging question is how to treat patients with no history of previous cardiac arrest or hemodynamically unstable ventricular tachycardia (VT). The value of ECG abnormalities, syncope, VT, and right/left ventricular involvement as predictors of SCD has been assessed in different studies with the purpose of better defining risk stratification in ARVC. Nevertheless, in spite of the growing amount of data, primary prevention in ARVC patients remains mostly an individual decision.

Multicenter experience with transvenous lead extraction in arrhythmogenic right ventricular cardiomyopathy (ARVC)

BACKGROUND

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is becoming a more commonly diagnosed entity with frequent need for coincident implantable cardioverter defibrillator (ICD) therapy. Given predominant right ventricular disease with thinning of the wall, there is concern regarding the safety of transvenous lead extraction (TLE) in ARVC.

METHODS

We performed a retrospective study of consecutive patients with ARVC undergoing TLE of ICD leads at three high-volume centers. Patient and lead characteristics, indications, outcomes, and extraction sheath (ES) use were analyzed.

RESULTS

Between 1999 and 2012, more than 2,000 lead extractions were performed at the three centers. Of these, 11 patients underwent 14 extractions meeting inclusion criteria. Mean implant duration was 74.5 months (range 6-140). In 11 patients, a total of 22 leads (16 high-voltage and six pace-sense leads) were extracted in 14 procedures. The cohort was 50% male with a mean age of 45 years (range, 25-56) and mean ejection fraction 55 ± 13%. The majority (64%) of leads were extracted due to lead malfunction, three patients had an ICD lead removed for exit block, and three patients underwent TLE for infectious complications (two local, one systemic). ES assistance with laser or mechanical cutting sheaths was employed in the vast majority of cases (85.7%). All leads were removed completely. There were no major procedural complications. In five cases, lead reimplantation encountered low-amplitude R waves requiring multiple attempted lead positions before final successful implant.

CONCLUSIONS

This is the first reported series of TLE in ARVC patients. TLE can be performed safely and effectively in patients with ARVC by experienced operators at high-volume centers with a low complication rate.

Implantable cardioverter defibrillators in arrhythmogenic right ventricular dysplasia/cardiomyopathy: patient outcomes, incidence of appropriate and inappropriate interventions, and complications

BACKGROUND

Arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C) is a cardiomyopathy characterized by ventricular arrhythmias and an abnormal right ventricle. Implantable cardioverter defibrillator (ICD) therapy may prevent sudden cardiac death in patients with ARVD/C. Currently, an overview of outcomes, appropriate and inappropriate interventions, and complications of ICD therapy in ARVD/C is lacking.

METHODS AND RESULTS

A literature search was performed to identify studies reporting outcome and complications in patients with ARVD/C who underwent ICD implantation. Of 641 articles screened, 24 studies on 18 cohorts were eligible for inclusion. In case of multiple publications on a cohort, the most recent publication was included in the meta-analysis. There were 610 patients (mean age, 40.4 years; 42% women), who had an ICD for primary or secondary prevention of sudden cardiac death. Risk factors for sudden cardiac death were presyncope (61%), syncope (31%), previous cardiac arrest (14%), ventricular tachycardia (58%), and ventricular fibrillation (6%). Antiarrhythmic medication consisted mostly of β-blockers (38%), amiodarone (14%), or sotalol (30%). During the 3.8-year follow-up, annualized cardiac mortality rate was 0.9%, annualized noncardiac mortality rate was 0.8%, and annualized heart transplant rate was 0.9%. The annualized appropriate and inappropriate ICD intervention rates were 9.5% and 3.7%, respectively. ICD-related complications consisted of difficult lead placement (18.4%), lead malfunction (9.8%), infection (1.4%), lead displacement (3.3%), and any complication (20.3%).

CONCLUSIONS

Cardiac and noncardiac mortality rates after ICD implantation in patients with ARVD/C are low. Appropriate ICD interventions occur at a rate of 9.5%/y. Inappropriate ICD interventions and complications lead to considerable ICD-related morbidity.

Long-term follow-up in patients with arrhythmogenic right ventricular cardiomyopathy

INTRODUCTION

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a major cause of sudden cardiac death due to tachyarrhythmias. The purpose of this study was to investigate the long-term prognosis in patients with ARVC and the incidence of rapid ventricular arrhythmias during follow-up.

METHODS

Thirty ARVC patients (19 male, 63.3%, mean age 48 ± 15 years) fulfilling modified Task Force criteria 2010 were included. Of them, 13 patients (43.3%) received implantable cardioverter-defibrillator (ICD) implantation. Rapid ventricular arrhythmia was defined as electrical storm or the occurrence of ventricular tachycardia (VT) or ventricular fibrillation (VF) with a cycle length of 240 ms or less that necessitate shock delivery to 2 or more times within a 24-hour period.

RESULTS

With a mean follow-up of 68 ± 10 months, 6 patients (20%) with ICD implantation had recurrent rapid VT/VF. One (3.3%) of them died of multiple shocks and SCD, and 5 (16.7%) had multiple ICD therapies due to VT/VF and electrical storm. The interval between the diagnosis of ARVC and occurrence of rapid VT/VF was 13.4 ± 4.9 months. Most (5/6, 83.3%) events of recurrent rapid VT/VF occurred within 2 years. Ablated patients who did not receive an ICD implant were totally free of rapid VT/VF.

CONCLUSIONS

For patients with ARVC, long-term prognosis is favorable. During a long-term follow-up, patients meeting the criteria for ICD implantation have a higher rate of rapid and potentially life-threatening arrhythmias. However, early and clustered recurrence of rapid VT/VF in patients with an ICD is common, whereas late occurrence of rapid VT/VF is very rare.

Association of heart rate variability with arrhythmic events in patients with arrhythmogenic right ventricular cardiomyopathy/dysplasia

BACKGROUND

Arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D) is associated with an increased risk of sudden cardiac death (SCD). Risk stratification of ARVC/D patients, however, remains an unresolved issue. In this study we investigated whether heart rate variability (HRV) can be helpful in identifying ARVC/D patients with increased risk of arrhythmic events.

METHODS AND RESULTS

We studied 30 consecutive patients (17 males; 45.4 ± 18 years) with ARVC/D, diagnosed according to guideline criteria; 15 patients (50%) had received an implantable cardioverter defibrillator (ICD) for primary SCD prevention. HRV was assessed on 24-h ECG Holter monitoring. The primary endpoint was the occurrence of major arrhythmic events (SCD, sustained ventricular tachycardia (VT), ICD therapy for sustained VT or ventricular fibrillation (VF)). During the follow-up period (19 ± 7 months), no deaths occurred, but 5 patients (17%) experienced arrhythmic events (4 VTs and 1 VF, all in the ICD group). All HRV parameters were significantly lower in patients with, compared with those without, arrhythmic events. Low-frequency amplitude was the most significant HRV variable associated with arrhythmic events in univariate Cox regression analysis (P=0.017), and was the only significant predictor of arrhythmic events in multivariable regression analysis (hazard ratio 0.88, P=0.047), together with unexplained syncope (hazard ratio 16.1, P=0.039).

CONCLUSIONS

Our data show that among ARVC/D patients HRV analysis might be helpful in identifying those with increased risk of major arrhythmic events.

Not just any ICD device in patients with long-QT syndrome

Patients with LQT syndrome are prone to lifethreatening arrhythmias. After surviving such an event, implantation of an ICD is indicated. There are, however, special subtle demands in the treatment of these patients. In this case report we describe our findings in a patient with LQT1 syndrome, and the pitfalls that can and must be avoided. (Neth Heart J 2007;15:418-21.).

Arrhythmogenic right ventricular cardiomyopathy/dysplasia: a not so rare "disease of the desmosome" with multiple clinical presentations

Arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D) is a rare but increasingly recognized form of a cardiomyopathy, involving primarily the right ventricle. Mutations in seven candidate genes coding for five desmosomal proteins (plakoglobin, plakophilin-2, desmoplakin, desmoglein-2, desmocollin-2), for the cardiac ryanodine receptor-2, for the transforming growth factor beta-3, and for the transmembrane protein 43, respectively, are pathogenetically important. A typical feature of the disease is the replacement of the right ventricular myocardium by fibrofatty infiltrates, leading to electrical instability including ventricular arrhythmias in the early stages, and reduced contractility and heart failure later on. The left ventricle may also be involved. Unfortunately, the disease is often diagnosed post mortem only, especially in young adults dying suddenly during exercise. Since the disease is inherited in up to 50% of cases, the screening of relatives is important. The implantable cardioverter defibrillator is an important therapeutic tool. Nevertheless, the mortality of the disease remains to be 2%-4% per year. Several clinical, electrocardiographic, and imaging parameters were identified as risk predictors for an adverse outcome. In this paper, we describe distinct clinical presentations of ARVC/D, review the genetic background of the disease, and discuss its diagnosis and treatment.

Arrhythmogenic right ventricular cardiomyopathy/dysplasia: risk stratification and therapy

Arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D) is an inherited heart muscle disease that occurs primarily in young and middle-age individuals. It is characterized by ventricular arrhythmias (VA), sudden death, and by heart failure occurring later in life (1 –5 ). Ventricular electrical instability may occur at any time during the disease depending upon possible different pathophysiologic mechanisms including: a) Inflammation and apoptosis leading to ventricular fibrillation; or b) Fibro-fatty tissue repair leading to scar-related ventricular tachycardia (VT). Heart failure may occur later in life secondary to slow, progressive loss of right and left ventricular myocardium (1 –8 ). The role of pharmacological therapy in controlling VA and preventing sudden death has been evaluated in single-center studies (9 ), and the results of catheter ablation have been described in small series of patients (10 –15 ). The efficacy and safety of implantable cardioverter/defibrillator (ICD) have also been reported in small, single-center studies (16 –19 ) and recently in larger single and multicenter studies (20 –27 ). The main questions regarding the risk stratification and the therapeutic strategy in ARVC/D are: 1) differential diagnosis with idiopathic VT (right ventricular outflow tract VT) in an apparently normal heart. The prognosis of this latter condition is usually excellent with rare cases of sudden cardiac death; 2) prognostic and therapeutic significance of noninvasive and invasive investigations including electrophysiologic study (EPS); 3) efficacy of antiarrhythmic drugs (AAD) to prevent VT and sudden cardiac death and the adverse effects of these drugs in this population; 4) indications and results of catheter ablation; 5) identification of patients at high risk of sudden cardiac death who need ICD implantation as well as the complications of ICD in a diseased right ventricular myocardium. It is important to recognize that ARVC/D is a progressive disease and risk factors may change during follow-up requiring periodic revaluation of risk as well as of therapy.

With the identification of family members who carry a disease causing gene, the therapeutic dilemma has broadened to include risk stratification in genotype positive family members who may have occasional ventricular ectopy or have no clinical evidence of the disease.

Outcome of cardioverter-defibrillator implant in patients with arrhythmogenic right ventricular cardiomyopathy

The aim of the present study was to investigate outcomes of implantable cardioverter-defibrillator (ICD) treatment in patients with arrhythmogenic right ventricular cardiomyopathy (ARVC). We reviewed baseline/follow-up data of 15 consecutive ARVC patients (mean age 55 +/- 15 years) and 30 randomly drawn patients with coronary artery disease (CAD) (mean age 60 +/- 10 years) with matching durations of follow-up (all implanted with ICDs for primary/secondary prevention of sudden death). At implant, appropriate placement of the RV lead was more difficult in ARVC patients. During follow-up (median 41 months), appropriate interventions for any ventricular tachyarrhythmias occurred in 8 (53%) ARVC patients and 17 (57%) CAD patients, but the occurrence of high rate (>240 beats/min) ventricular tachyarrhythmias was higher in ARVC patients. Inappropriate ICD interventions occurred in 5 (33%) ARVC patients and 10 (33%) CAD patients. Lead-related adverse events requiring surgical revision occurred in 7 (47%) ARVC patients as compared with 4 (13%) CAD patients (P = 0.0004). While ICD implantation is highly effective for prevention of sudden death in ARVC, it does carry elevated burdens of long-term lead-related adverse events. These findings underline the need of careful follow-up in ARVC aimed at early recognition of complications that can impair ICD function.

Use of a Coronary Sinus Lead and Biventricular ICD to Correct a Sensing Abnormality in a Patient with Arrhythmogenic Right Ventricular Dysplasia/Cardiomyopathy

Implantable cardioverter defibrillators (ICDs) are frequently offered to patients with arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C). Yet ICDs in these patients may be complicated by poor sensed amplitudes resulting from fatty and fibrous tissue replacement of right ventricular myocardium. We present the case of a patient with ARVD/C who had inappropriate detection of ventricular tachycardia with a single-chamber ICD due to poor sensed right ventricular amplitudes. We discuss how the use of a bipolar coronary sinus lead and a biventricular ICD generator with a novel header configuration solved the problem.

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.

The impact of implantable cardioverter-defibrillator therapy on survival in autosomal-dominant arrhythmogenic right ventricular cardiomyopathy (ARVD5)

OBJECTIVES

We sought to determine the impact of implantable cardioverter-defibrillator (ICD) therapy in patients with familial arrhythmogenic right ventricular cardiomyopathy (ARVC).

BACKGROUND

Arrhythmogenic right ventricular cardiomyopathy is a cause of sudden cardiac death, which may be prevented by ICD.

METHODS

We studied 11 families in which a 3p25 deoxyribonucleic acid (DNA) haplotype at locus ARVD5 segregated with disease and compared mortality in subjects who received an ICD with that in control subjects who were matched for age, gender, ARVC status, and family. Subjects (n = 367) at 50% a priori risk of inheriting ARVC were classified as high risk (HR) (n = 197), low risk (n = 92), or unknown (n = 78) on the basis of clinical events, DNA haplotyping, and/or pedigree position. Forty-eight HR subjects (30 males, [median age 32 years] and 18 females [median age 41 years]) were followed after ICD (secondary to ventricular tachycardia [VT] in 27%). Survival was compared with 58 HR control subjects who were alive at the same age to-the-day at which the ICD subject received the device.

RESULTS

In the HR group, 50% of males were dead by 39 years and females by 71 years: relative risk of death was 5.1 (95% confidence interval 3 to 8.5) for males. The five-year mortality rate after ICD in males was zero compared with 28% in control subjects (p = 0.009). Within five years, the ICD fired for VT in 70% and for VT >240 beats/min in 30%, with no difference in discharge rate when analyzed by ICD indication.

CONCLUSIONS

The unknown mutation at the ARVD5 locus causing ARVC results in high mortality. Risk stratification using genetic haplotyping and ICD therapy produced improved survival for males.

The Role of Genotyping in Diagnosing Cardiac Channelopathies

The role of genotyping for diagnosis of the cardiac ion channelopathies is a work in progress. No formal guidelines or other publications discussing current recommendations for genotyping exist, particularly for clinical/commercial genotyping. Further, the field is changing rapidly, opinions vary and, additionally, circumstances inside the US are different from outside. The following considerations are a current summary based on a review of the literature, discussions with experts in the field, and our own opinions and also include a brief discussion about genotyping for therapeutic decision making. Research-based genotyping is very important for continued understanding of the details of pathophysiology and the complex regulatory processes in these diseases. Clinical/commercial genotyping for diagnosis is important for identifying patients with reduced penetrance of the phenotype since effective therapies to prevent sudden death exist. Clinical genotyping for therapeutic advantage has limited application at present but will become much more important if and when genotype-/mutation-type specific therapies are shown to be effective. The recommendations will progressively change as new research findings and new genotyping technologies appear.

Implantable cardioverter-defibrillators in patients with arrhythmogenic right ventricular dysplasia/cardiomyopathy

OBJECTIVES

The aim of this study was to assess the outcome of arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C) patients treated with an implantable cardioverter-defibrillator (ICD).

BACKGROUND

Arrhythmogenic right ventricular dysplasia/cardiomyopathy is associated with tachyarrhythmia and an increased risk of sudden death.

METHODS

This study included 42 ARVD/C patients with ICDs (52% male, age 6 to 69 years, median 37 years) followed at our center.

RESULTS

Mean follow-up was 42 +/- 26 months (range 4 to 135 months). Complications associated with ICD implantation included need for lead repositioning (n = 3) and system infection (n = 2). During follow-up, one patient died of a brain malignancy and one had heart transplantation. Lead replacement was required in six patients as a result of lead fracture and insulation damage (n = 4) or change in thresholds (n = 2). During this period, 33 of 42 (78%) patients received a median of 4 (range 1 to 75) appropriate ICD interventions. The median period between ICD implantation and the first firing was 9 months (range 0.1 to 66 months). The ICD firing storms were observed in five patients. Inappropriate interventions were seen in 10 patients. Predictors of appropriate firing were induction of ventricular tachycardia (VT) during electrophysiologic study (EPS) (84% vs. 44%, p = 0.024), detection of spontaneous VT (70% vs. 15%, p = 0.001), male versus female gender (91% vs. 65%, p = 0.04), and severe right ventricular dilation (39% vs. 0%, p = 0.013). Using multivariate analysis, VT induction during EPS was associated with increased risk for firing in ARVD/C patients; odds ratio 11.2 (95% confidence interval 1.23 to 101.24, p = 0.031).

CONCLUSIONS

Patients with ARVD/C have a high arrhythmia rate requiring appropriate ICD interventions. The ICD therapy appears to be well tolerated and important in the management of patients with ARVD/C.

Implantable cardioverter/defibrillator therapy in arrhythmogenic right ventricular cardiomyopathy: single-center experience of long-term follow-up and complications in 60 patients

BACKGROUND

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a major cause of ventricular tachycardia (VT) and cardiac arrest in young patients. We hypothesized that treatment with implantable cardioverter/defibrillators (ICDs) is safe and improves the long-term prognosis of ARVC patients at high risk of sudden death.

METHODS AND RESULTS

Sixty patients with ARVC (aged 43+/-16 years) were treated with transvenous ICD systems. Despite a higher number of right ventricular sites tested for adequate lead positions (P<0.05), lower R-wave amplitudes (P<0.001) were achieved in ARVC patients compared with other entities. During follow-up of 80+/-43 months (396 patient-years), event-free survival was 49%, 30%, 26%, and 26% for appropriate ICD therapies and 79%, 64%, 59%, and 56% for potentially fatal VT (>240 bpm) after 1, 3, 5, and 7 years, respectively. Multivariate analysis identified extensive right ventricular dysfunction as an independent predictor of appropriate ICD discharge. Fifty-three adverse events occurred in 37 patients during the perioperative (n=10) or follow-up (n=43) period, mainly related to the leads (n=31 in 21 patients). No lead perforation was observed. Freedom from adverse events was 90%, 78%, 56%, and 42% and freedom from lead-related complications was 95%, 85%, 74%, and 63% after 1, 3, 5, and 7 years, respectively.

CONCLUSIONS

These results strongly suggest an improvement in long-term prognosis by ICD therapy in high-risk patients with ARVC. However, meticulous placement and long-term observation of transvenous lead performance with focus on sensing function are required for the prevention and/or early recognition of disease progression and lead-related morbidity during long-term follow-up of ICD therapy in ARVC.

Implantable cardioverter-defibrillator therapy for prevention of sudden death in patients with arrhythmogenic right ventricular cardiomyopathy/dysplasia

BACKGROUND

Arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D) is a condition associated with the risk of sudden death (SD).

METHODS AND RESULTS

We conducted a multicenter study of the impact of the implantable cardioverter-defibrillator (ICD) for prevention of SD in 132 patients (93 males and 39 females, age 40+/-15 years) with ARVC/D. Implant indications were a history of cardiac arrest in 13 patients (10%), sustained ventricular tachycardia in 82 (62%), syncope in 21 (16%), and other in 16 (12%). During a mean follow-up of 39+/-25 months, 64 patients (48%) had appropriate ICD interventions, 21 (16%) had inappropriate interventions, and 19 (14%) had ICD-related complications. Fifty-three (83%) of the 64 patients with appropriate interventions received antiarrhythmic drug therapy at the time of first ICD discharge. Programmed ventricular stimulation was of limited value in identifying patients at risk of tachyarrhythmias during the follow-up (positive predictive value 49%, negative predictive value 54%). Four patients (3%) died, and 32 (24%) experienced ventricular fibrillation/flutter that in all likelihood would have been fatal in the absence of the device. At 36 months, the actual patient survival rate was 96% compared with the ventricular fibrillation/flutter-free survival rate of 72% (P<0.001). Patients who received implants because of ventricular tachycardia without hemodynamic compromise had a significantly lower incidence of ventricular fibrillation/flutter (log rank=0.01). History of cardiac arrest or ventricular tachycardia with hemodynamic compromise, younger age, and left ventricular involvement were independent predictors of ventricular fibrillation/flutter.

CONCLUSIONS

In patients with ARVC/D, ICD therapy provided life-saving protection by effectively terminating life-threatening ventricular arrhythmias. Patients who were prone to ventricular fibrillation/flutter could be identified on the basis of clinical presentation, irrespective of programmed ventricular stimulation outcome.

Implantable cardioverter defibrillator in high-risk long QT syndrome patients

INTRODUCTION

Implantable cardioverter defibrillators (ICDs) are increasingly being used in high-risk long QT syndrome (LQTS) patients, but there are limited data regarding clinical experience with this therapeutic modality. The aim of this study is to describe the clinical characteristics of 125 LQTS patients treated with ICDs compared with LQTS patients having similar risk indications who were not treated with ICDs. Among 125 LQTS patients with ICDs, there were 54 cardiac arrest survivors, 19 patients who had ICDs implanted due to recurrent syncope despite beta-blocker therapy, and 52 patients with ICDs implanted due to other reasons, including syncope and LQTS-related sudden death in a close family member. Patients with cardiac arrest and those with recurrent syncope despite beta-blocker therapy (n = 73) were compared to 161 LQTS patients who had similar indications (89 cardiac arrest and 72 recurrent syncope despite beta-blocker therapy) but did not receive ICDs. Total mortality was the endpoint of the analysis. There was 1 (1.3%) death in 73 ICD patients followed an average of 3 years, whereas there were 26 deaths (16%) in non-ICD patients during mean 8-year follow-up (P = 0.07 from log rank test from Kaplan-Meier curves).

CONCLUSION

ICDs provide an important therapeutic option to prevent sudden arrhythmic death in high-risk LQTS patients. A long-term prospective study is needed to determine the benefit of this therapeutic modality in LQTS patients.

Implantable cardioverter-defibrillators in arrhythmias: a rapid and systematic review of effectiveness

OBJECTIVE

To review the effectiveness of implantable cardioverter-defibrillators (ICDs) in the management of risk factors for sudden cardiac death.

DESIGN

Systematic review of randomised controlled trials identified from searching eight electronic databases, bibliographies of relevant studies, and consulting experts.

MAIN OUTCOME MEASURES

Absolute and relative reduction in mortality.

RESULTS

Seven trials met the inclusion criteria. These showed changes in absolute risk of total mortality ranging from +1.7% to -22.8% (relative risk reductions -7% to +54%). Estimated benefits from ICD treatment compared with conventional drug treatment at three years were 0.23 to 0.80 additional years of life.

CONCLUSIONS

Evidence suggests that ICDs reduce total mortality in particular subgroups of patients at high risk of ventricular arrhythmias. The optimal strategy for identifying the patients who could benefit most is not clearly established. Ongoing trials into the treatment of cardiac failure with ICDs may provide further evidence about subgroups in whom ICDs are most cost effective.

[The Brugada syndrome]

nema

Multi-morphology wide QRS tachycardias in a patient without structural heart disease: an unusual presentation of ventricular tachycardia

Ventricular tachycardia occurs infrequently in patients without structural heart disease. These tachycardias commonly originate from the right ventricular outflow tract. However, the presence of more than one arrhythmogenic substrate in a patient without structural heart disease is rare. We report such a 48-year old patient with no structural heart disease who presented with three morphology wide QRS tachycardia. A brief review of the pathophysiology and management is discussed.

Congenital long QT syndromes and Brugada syndrome: the arrhythmogenic ion channel disorders

Congenital long QT syndromes (LQTS) and Brugada syndrome are hereditary disorders of cardiac ion channels which result in life-threatening cardiac arrhythmias or sudden cardiac death in patients with anatomically normal hearts. The pathogenesis of these dramatic events has been partially elucidated with the identification of the individual ion channels involved and understanding of the effect of some disease-causing mutations on the membrane currents and action potential. The clinical spectrum of congenital LQTS is broader than previously thought and involves certain patients previously diagnosed with idiosyncratic drug-induced proarrhythmia. The initial treatment for congenital LQTS patients involves beta-blockers in most cases. Indications for implantable cardioverter-defibrillator (ICD) or pace-maker (PM) implantation in selected individuals continue to evolve.

Long term results of cardioverter-defibrillator implantation in patients with right ventricular dysplasia and malignant ventricular tachyarrhythmias

OBJECTIVE

To study the outcome of patients with arrhythmogenic right ventricular dysplasia treated with an implantable cardioverter-defibrillator (ICD) for ventricular tachyarrhythmias complicated by haemodynamic collapse.

DESIGN

Observational study.

SETTING

University hospital.

PATIENTS

Nine consecutive patients (eight male, one female; mean (SD) age, 36 (18) years) with arrhythmogenic right ventricular dysplasia presenting with ventricular tachycardia and haemodynamic collapse (n = 6) or ventricular fibrillation (n = 3), treated with an ICD.

MAIN OUTCOME MEASURES

Survival; numbers of and reasons for appropriate and inappropriate ICD interventions.

RESULTS

After a mean (SD) follow up of 32 (24) months, all patients were alive. Six patients received a median of 19 (range 2-306) appropriate ICD interventions for events detected in the ventricular tachycardia window; four received a median of 2 (range 1-19) appropriate ICD interventions for events detected in the ventricular fibrillation window. Inappropriate interventions were seen for sinus tachycardia (18 episodes in three patients), atrial fibrillation (three episodes in one patient), and for non-sustained polymorphic ventricular tachycardia (one episode in one patient).

CONCLUSIONS

Patients with arrhythmogenic right ventricular dysplasia and malignant ventricular arrhythmias have a high recurrence rate requiring appropriate ICD interventions, but they also often have inappropriate interventions. Programming the device is difficult because this population develops supraventricular and ventricular tachyarrhythmias with similar rates.

Implantable defibrillator therapy in Naxos disease

Naxos disease is a unique form of right ventricular cardiomyopathy with a high prevalence of malignant ventricular arrhythmias, including sudden cardiac death. As a hereditary systemic disease confined to a small island, it has been closely studied over the last 15 years. The implantation of an automatic defibrillator provides an alternative form of antiarrhythmic management to improve life expectancy in these high risk cardiac patients. We present the first two Naxos disease patients with malignant ventricular arrhythmias who had defibrillator implantation.

Long-term follow-up of patients with long-QT syndrome treated with beta-blockers and continuous pacing

BACKGROUND

The long-QT syndrome is associated with sudden cardiac death. Combination of beta-blocker and pacing therapy has been proposed for treatment of drug-resistant patients. The purpose of this study was to summarize our long-term experience with combined therapy in patients with long-QT syndrome.

METHODS AND RESULTS

A total of 37 patients with idiopathic long-QT syndrome were treated with combined therapy consisting of continuous cardiac pacing and maximally tolerated beta-blocker therapy and followed up for 6.3+/-4. 6 years (mean+/-SD). The group consisted of 32 female and 5 male patients with a mean age of 31.6 years. The mean paced rate was 82+/-7 bpm (range, 60 to 100 bpm). On follow-up, recurrent symptoms caused by pacemaker malfunction were documented in 3 patients. Four patients died during the follow-up period: 2 adolescents stopped beta-blocker therapy, 1 patient died suddenly while treated with combined therapy, and 1 patient died of unrelated causes. In addition, 3 patients had resuscitated cardiac arrest while on combined therapy, and 1 patient had repeated, appropriate implantable cardioverter-defibrillator discharges on follow-up.

CONCLUSIONS

Because 28 of 37 patients remain without symptoms with beta-blocker therapy and continuous pacing, combined therapy appears to provide reasonable, long-term control for this high-risk group. However, the incidence of sudden death and aborted sudden death (24% in all patients and 17% in compliant patients) strongly suggests the use of a "back-up" defibrillator, particularly in noncompliant adolescent patients. Implantable cardioverter-defibrillator therapy, however, may be associated with recurrent shocks in susceptible patients.

Late outcome of survivors of idiopathic ventricular fibrillation

This report describes clinical, hemodynamic, and electrophysiologic characteristics of 18 consecutive survivors of sudden cardiac arrest due to idiopathic ventricular fibrillation (VF) between 1986 and 1996. Long-term data in relation to the prescribed therapy are presented. The mean age of the 18 patients was 48 +/- 14 years (median 49). Electrophysiologic studies showed a low inducibility of sustained ventricular tachyarrhythmias in 4 patients (22%). Treatment consisted of class III agents, beta blockers, or implantable cardioverter-defibrillators. Two patients were discharged without any therapy. Therapy control was undertaken either by serial drug testing or by the empirical approach. Serious complications of therapy occurred in 2 patients: 1 patient experienced a proarrhythmic effect of antiarrhythmic drug therapy, and the other patient received multiple inadequate defibrillator discharges due to a defect in the transvenous lead. All but 1 patient (94%) remained free of recurrences of sudden cardiac arrest during a follow-up time of 45 +/- 29 months (median 41). One patient died 2 weeks after surviving cardiac arrest due to intractable VF while receiving sotalol treatment. Therapy guided by electrophysiologic studies did not have any impact on survival. Adverse effects or noncompliance led to discontinuation of drug therapy in 7 patients after a mean period of 31 +/- 30 months. Without any treatment 9 patients remained without recurrences over 45 +/- 33 months. Because of the absence of risk factors for arrhythmia recurrence and criteria to select therapy, randomized prospective studies are warranted to assess the optimal therapies in these young, ostensibly healthy patients.

[Arrhythmogenic right ventricular cardiomyopathy. Etiology, diagnosis and therapy]

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is characterized by regional atrophy of right ventricular myocardium and subsequent replacement by fatty and fibrous tissue. The disease manifests in young adulthood with a predominance of males. Hallmarks of ARVC are ventricular tachyarrhythmias of left bundle branch block pattern which frequently occur during exercise. However, sudden death may also be the first manifestation of the disease. Characteristic findings are repolarization abnormalities and QRS prolongation in the right precordial leads of the surface ECG and regional abnormalities of right ventricular structure and wall motion. Left ventricular involvement may occur in later stages of the disease but rarely leads to progressive biventricular heart failure. Therapeutic efforts are mainly directed to the treatment of ventricular tachyarrhythmias and the prevention of sudden death. A tailored treatment strategy including antiarrhythmic drug therapy, catheter ablation and implantation of cardioverter-defibrillators may be used to improve the long-term prognosis of patients with ARVC.

Arrhythmogenic right ventricular dysplasia: clinical results with implantable cardioverter defibrillators

Arrhythmogenic right ventricular dysplasia is a clinical entity characterized by fatty infiltration of the right ventricle and left bundle morphology ventricular tachycardia occurring in young patients. The most common cause of death is tachyarrhythmic. Pharmacological and nonpharmacological therapies, including implantable cardioverter defibrillators, have been used to treat the arrhythmias. However, right ventricular endocardial leads in this population may be associated with an increased risk of perforation and suboptimal sensing and defibrillation efficacy due to the diseased right ventricle. We report on 12 patients with arrhythmogenic right ventricular dysplasia who were treated with implantable cardioverter defibrillators. The mean age was 31 +/- 9 years (range 15-48). Patients presented with presyncope (5), syncope (4), or cardiac arrest (3). All patients had electrocardiographic abnormalities characteristic of the condition. During programmed electrical stimulation nine patients had sustained ventricular tachycardia, while three patients had no inducible arrhythmia. Transvenous leads were placed in nine patients. In these patients pacing thresholds were significantly higher, R-wave amplitudes were significantly lower and defibrillation thresholds were not significantly different than in a cohort of patients without right ventricular dysplasia. There were no acute or chronic complications of right ventricular lead placement. Follow-up averaged 22 +/- 13 months (range 1-45). There was one sudden death at 1 month of follow-up. Of the 12 patients, 8 have had appropriate therapy delivered by the implantable defibrillator. Six patients are currently on sotalol to reduce the frequency of implantable defibrillator discharges. In conclusion, implantable cardioverter defibrillators with nonthoracotomy leads are feasible and safe in patients with arrhythmogenic right ventricular dysplasia. The frequency of appropriate therapy is high, supporting the use of implantable cardioverter defibrillators in this population.

Long-term follow-up of patients treated with implantable cardioverter defibrillators in a Danish centre. Accurrence ICD therpay and patient survivors

The aim of the this prospective follow-up study was to evaluate long-term survival and implantable cardioverter-defibrillator (ICD) therapy for ventricular tachyarrhythmias in patients treated with an ICD in a Danish centre. A total of 140 consecutive patients (112 men), of which 70.7% had coronary artery disease, received an ICD at Skejby University Hospital between March 1989 and October 1996. Mean age was 55.6 +/- 14.6 years (range 14-78 years). After implantation, 136 of the patients were followed for a median (range) of 17.7 (0.4-74.1) months. Survival, mode of death and incidence of appropriate ICD therapy and therapy due to potential life-threatening ventricular tachyarrhythmia were the main outcome measures. Kaplan-Meier plots representing total survival, cardiac death, sudden cardiac death and first episode of ICD therapy are presented. After 1, 2, 3 and 4 years, respectively, the cumulative incidences of death were 9, 18, 20 and 24%, of cardiac death 4, 11, 14 and 18%, and of sudden cardiac death 2, 3, 6 and 6%. The cumulative incidences of appropriate therapy after 1, 2, 3 and 4 years were 47, 56, 66 and 80%, respectively. The cumulative incidences of cardiac death after the first episode of appropriate therapy were 9, 11, 15 and 20% after 1, 2, 3 and 4 years, respectively. The occurrence of ICD therapy and patient survival in the present study population treated with ICD at a Danish centre was comparable to results published previously from other larger centres. The rate of sudden cardiac death was low and most of our patients received appropriate ICD therapy during follow-up, indicating correct patient selection and probable benefit of the ICD device.

Implantable cardioverter defibrillator therapy in a patient with the idiopathic long QT syndrome

The idiopathic long QT syndrome (LQTS) carries a high mortality in untreated patients. Administration of beta-receptor antagonists is considered the treatment of choice. Data concerning the usefulness of implantable cardioverter-defibrillator (ICD) therapy in this condition are sparse. We report on a 29-year-old female with LQTS who was treated with propranolol, but also underwent implantation of an ICD as a fail-safe therapy. During the next 17 months, the patient was asymptomatic. However, after skipping her propranolol for 3 days, she had several syncopal spells with concomitant device therapy. ICD interrogation revealed a total of 55 nonsustained runs of ventricular tachycardia and 16 sustained episodes that were correctly identified by the device and respectively terminated by the first shock. This case report demonstrates that in selected patients with the LQTS, using ICD therapy as a fail-safe treatment may be life-saving, particularly when compliance to medical therapy is uncertain.

Five-year experience with implantable defibrillators in children

Cardioverter-defibrillators were implanted in children aged 4 to 16 years over a 5-year period with no mortality and eventual clinically appropriate shocks in 6 of 11 patients. Both transvenous and epicardial implantable cardioverter-defibrillators were safe and effective in children resuscitated from sudden death or at high risk for sudden death.

Clinical assessment of adrenergic tone and responsiveness to beta-blocker therapy in patients with symptomatic ventricular tachycardia and no apparent structural heart disease

To further define the relation between changing adrenergic tone, beta-blocker therapy, and clinical ventricular tachycardia (VT), we evaluated these factors in 35 patients with VT unrelated to coronary artery disease or ventricular dysfunction. Testing included Holter monitoring (91% had VT), exercise test (69% had VT), Adrenergic responsiveness of VT was graded according to diurnal variation, response to exercise, isoproterenol infusion, and response to beta-blockers. beta-Blockers were effective and well tolerated in this population. There was also a predictable relation between changing adrenergic tone and the arrhythmia response to beta-blocker therapy.