Hypertrophic cardiomyopathy: role of the implantable cardioverter-defibrillator

Temporal Incidence of Appropriate and Inappropriate Therapy and Mortality in Secondary Prevention ICD Patients by Cardiac Diagnosis

OBJECTIVES

This study sought to estimate the temporal development in rates and incidences of appropriate and inappropriate implantable cardioverter-defibrillator (ICD) therapy and shocks by cardiac diagnosis in a real-world population of patients with secondary prevention ICDs.

BACKGROUND

Data on cardiac diagnoses and temporal development of ICD therapies in patients with secondary prevention ICDs are limited.

METHODS

Patients (N = 4,587) with a secondary prevention ICD were identified from the Danish Pacemaker and ICD Register (January 1, 2007, to December 31, 2016) and linked to nationwide administrative registers. The outcome of appropriate and inappropriate ICD therapy and all-cause mortality were analyzed by annual event rates, cumulative incidence plots, and Cox regression models.

RESULTS

During a mean follow-up of 3.6 ± 2.4 years, 1,362 patients (30%) experienced appropriate ICD therapy (16.8% shocks), and 350 patients (7.6%) experienced inappropriate ICD therapy (4.6% shocks). From 2007 to 2016, there was a significant temporal reduction in both appropriate and inappropriate ICD therapy from 28.2 (95% confidence interval [CI]: 21.6 to 37.0) to 7.9 (95% CI: 6.8 to 9.1) and 10.0 (95% CI: 6.4 to 15.5) to 1.0 (95% CI: 0.7 to 1.5) per 100 person-years (p for trends <0.001). Multivariate Cox regression analyses showed that arrhythmogenic right ventricular cardiomyopathy was associated with the highest probability of appropriate ICD therapy (hazard ratio: 2.45; 95% CI: 1.77 to 3.39; p < 0.0001), whereas patients with hypertrophic cardiomyopathy had the lowest probability (hazard ratio: 0.62; 95% CI: 0.42 to 0.93; p = 0.0196) when compared to patients with ischemic heart disease.

CONCLUSIONS

In this nationwide real-life cohort of patients with secondary prevention ICDs, we observed a significant temporal decline in delivered appropriate and inappropriate shocks and ICD therapies in the last decade. A large proportion of patients still experienced ICD therapy but with significant differences by cardiac diagnosis.

Síndrome de Brugada. Aspectos fisiopatológicos, clínicos y su asociación con enfermedades infecciosas

El síndrome de Brugada (SBr) es una enfermedad cardiaca no estructural que afecta los canales iónicos cardiacos, caracterizado por manifestaciones clínicas como arritmias, taquicardia, síncope y muerte súbita, entre otras. Su diagnóstico es netamente electrocardiográfico, con un patrón altamente sugestivo pero no patognomónico, por lo que existen diagnósticos diferenciales desde el punto de vista electrocardiográfico.Existen tres patrones electrocardiográficos en los pacientes con SBr, de los cuales el tipo I es el patrón más característico. Actualmente, múltiples genes se han relacionado con la presentación de este síndrome, entre los cuales se destaca el gen SCN5A, el más descrito en la literatura. Se conoce que este síndrome es más frecuente en el género masculino; sin embargo, no existen estudios epidemiológicos en Latinoamérica que lo confirmen. Pese a que la investigación alrededor de los mecanismos causales del síndrome ha avanzado, existen varias cuestiones sin resolver, como su desenmascaramiento por los signos que producen algunas enfermedades infecciosas causadas principalmente por virus. Por lo tanto, dada la relevancia clínica del tema para el médico general y para el especialista, el objetivo de esta revisión es describir no solo aspectos fisiopatológicos y clínicos de la enfermedad, sino también resaltar casos de pacientes con enfermedades infecciosas quienes posteriormente han sido diagnosticados con el síndrome de Brugada.

Implantable cardioverter-defibrillator in hypertrophic cardiomyopathy

Sudden cardiac death (SCD) is the most devastating complication in hypertrophic cardiomyopathy (HCM). The implantable cardioverter–defibrillator (ICD) has proven to be effective in SCD prevention in several clinical scenarios. In HCM population, it has demonstrated to successfully abort life-threatening ventricular arrhythmias despite the extreme morphology characteristic of HCM, often with massive degrees of left ventricular hypertrophy and/or LV outflow tract obstruction. Studies showed a high rate of appropriate intervention in secondary prevention and in primary prevention of patients considered at high risk. This appropriate intervention rate is even more significant considering the young and otherwise healthy patients that compose HCM population. Since SCD incidence in HCM is relatively low, optimal identification of patients at high risk is crucial. Classical strategy of risk stratification based on clinical risk factors has several limitations and has proven to overestimate risk. A new risk prediction model that provides individual 5-year estimated risk appears to be superior to traditional models based on bivariate risk factors. Perioperative complications seem to be similar to those related to the implant of other cardiac devices, while long-term complications have been traditionally in the spotlight. HCM patients are considered more vulnerable to ICD-related complications and inappropriate ICD therapy because of their young age at implant and increased prevalence of atrial fibrillation, but long-term follow-up data on ICD-related complications in general practice is limited. The subcutaneous implantable cardioverter defibrillator seems to be a safe and effective alternative in HCM, although long-term data are scarce.

Implantable cardioverter defibrillator therapy in hypertrophic cardiomyopathy: an updated systematic review and meta-analysis of outcomes and complications

BACKGROUND

Since the introduction of the implantable cardioverter-defibrillator (ICD) in patients with hypertrophic cardiomyopathy (HCM), the incidence of sudden cardiac death (SCD) has been significantly reduced. Given its widespread use, it is important to identify the outcomes associated with ICD use in patients with HCM. The present paper is a systematic review and meta-analysis of the rates of appropriate and inappropriate interventions, mortality, and device complications in HCM patients with an ICD.

METHODS

We conducted a systematic review and meta-analysis on 27 studies reporting outcomes and complications after ICD implantation in patients with HCM. ICD interventions, device complications, and mortality were extracted for analysis.

RESULTS

A total of 3,797 patients with HCM and ICD implantation were included (mean age, 44.5 years; 63% male), of which 83% of patients had an ICD for primary prevention of SCD. The cardiac mortality was 0.9% (95% CI: 0.7-1.3) per year and non-cardiac mortality was 0.8% (95% CI: 0.6-1.2) per year. Annualized appropriate intervention rate was 4.8% and annualized inappropriate intervention was 4.9%. The annual incidence of lead malfunction, lead displacement and infection was 1.4%, 1.3%, and 1.1%, respectively.

CONCLUSIONS

ICD use in patients with HCM produces low rates of cardiac and non-cardiac mortality, and an appropriate intervention rate of 4.8% per year. However, moderate rates of inappropriate intervention and device complications warrant careful patient selection in order to optimize the risk to benefit ratio in this select group of patients.

Contemporary strategies for risk stratification and prevention of sudden death with the implantable defibrillator in hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is regarded as the most common nontraumatic cause of sudden death (SD) in young people (including trained athletes). Introduction of implantable cardioverter-defibrillators (ICD) to HCM 15 years ago represented a new paradigm for clinical practice and probably the most significant advance in management of this disease. ICDs offer protection against SD by terminating potentially lethal ventricular tachyarrhythmias (11%/year secondary and 4%/year primary prevention), although implant decisions are weighed against the possibility of device-related complications (5%/year). ICDs have altered the natural history of HCM, creating the opportunity for extended or normal longevity for many patients. However, assessing SD risk and targeting appropriate candidates for prophylactic device therapy can be compounded by unpredictability of the underlying arrhythmogenic substrate, evident by delays ≥10 years between implant and first ICD intervention. Multiple or a single strong risk marker within the clinical profile of an individual HCM patient can justify consideration for a primary-prevention ICD when combined with physician judgment and shared decision making. The role of the mathematical SD risk score proposed by the European Society of Cardiology to identify patients who benefit from ICD therapy is incompletely resolved. Contemporary treatment interventions and advanced risk stratification using ≥1 conventional markers have served the HCM patient population well, with reduced disease-related mortality rates across all age groups to <1%/year, due largely to the penetration of ICDs into HCM practice. Prevention of SD has now become an integral, albeit challenging, component of HCM management, contributing importantly to its emergence as a contemporary treatable cardiac disease.

Implantable cardioverter-defibrillator harm in young patients with inherited arrhythmia syndromes: A systematic review and meta-analysis of inappropriate shocks and complications

BACKGROUND

Implantable cardioverter-defibrillators (ICDs) are implanted with the intention to prolong life in selected patients with inherited arrhythmia syndromes, but ICD implantation is also associated with inappropriate shocks and complications.

OBJECTIVE

We aimed to quantify the rate of inappropriate shocks and other ICD-related complications to be able to weigh benefit and harm in these patients.

METHODS

We performed a systematic review and meta-analysis of inappropriate shock and/or other ICD-related complication rates, including ICD-related mortality, in patients with inherited arrhythmia syndromes, that is, arrhythmogenic right ventricular cardiomyopathy/dysplasia, Brugada syndrome, catecholaminergic polymorphic ventricular tachycardia, hypertrophic cardiomyopathy, dilated cardiomyopathy due to a mutation in the lamin A/C gene, long QT syndrome, and short QT syndrome. We searched MEDLINE and EMBASE from inception to May 30, 2014.

RESULTS

Of 2471 unique citations, 63 studies comprising 4916 patients with inherited arrhythmia syndromes (mean age of 39 ± 15 years) were included. Inappropriate shocks occurred in 20% of patients (crude annual rate of 4.7% per year), with a significantly higher rate in studies published before 2008 (6.1% per year vs 4.1% per year). Moreover, 22% experienced ICD-related complications (4.4% per year) and there was a 0.5% ICD-related mortality (0.08% per year).

CONCLUSION

ICD implantation carries a significant risk of inappropriate shocks and inhospital and postdischarge complications in relatively young patients with inherited arrhythmia syndromes. These data can be used to better inform patients and physicians about the expected risk of adverse ICD events and thereby facilitate shared decision making.

Family screening in hypertrophic cardiomyopathy is underperformed, but can be improved by a specialised clinic

BACKGROUND

Hypertrophic cardiomyopathy (HCM) causes significant morbidity and sudden death. First-degree relatives (FDR) of affected patients are at risk due to autosomal dominant inheritance. Guidelines recommend clinical screening, including echocardiography, for all FDR.

AIM

We sought to determine adherence to these guidelines, and whether a specialised HCM clinic improves screening rates.

METHOD

This 12-month prospective follow-up study obtained family pedigrees from all patients referred to the HCM Clinic @ The Alfred. The number of living FDR was determined, and whether they had previously been assessed by echocardiography. One year after a coordinated clinic-based family screening approach was instituted, the number of additionally screened FDR was recorded.

RESULTS

Three hundred and eight living FDR of 61 HCM patients were identified. Of these, echocardiography had previously been performed in only 80 (26%), yielding 13 (16%) additional cases of HCM. Twelve months after attendance at our clinic, 51 additional FDR were screened (64% improvement) and 8 new cases of HCM were identified.

CONCLUSIONS

Recommended family screening for HCM is underperformed, resulting in missed opportunities to detect subclinical HCM. A coordinated approach through a specialised HCM clinic improves screening rates, thus referral to such a service should be considered for all patients with HCM and their families.

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.

Life expectancy gains and cost-effectiveness of implantable cardioverter/defibrillators for the primary prevention of sudden cardiac death in patients with hypertrophic cardiomyopathy

BACKGROUND

Sudden cardiac death (SCD) is a devastating complication of hypertrophic cardiomyopathy (HCM). The optimal strategy for the primary prevention of SCD in HCM remains controversial.

METHODS

Using a Markov model, we compared the health benefits and cost-effectiveness of 3 strategies for the primary prevention of SCD: implantable cardioverter/defibrillator (ICD) insertion, amiodarone therapy, or no therapy. We modeled hypothetical cohorts of 45-year-old patients with HCM with no history of cardiac arrest but at significant risk of SCD (3%/y).

RESULTS

Over a lifetime, compared with no therapy, ICD therapy increased quality-adjusted survival by 4.7 quality-adjusted life years (QALYs) at an additional cost of $142,800 ($30,000 per QALY), whereas amiodarone increased quality-adjusted survival by 2.8 QALYs at an additional cost of $104,900 ($37,300 per QALY). Compared with no therapy, ICD therapy would cost < $50,000 per QALY for patients (i) aged 25, with > or = 1 risk factors for SCD, and (ii) aged 45 or 65, with > or = 2 risk factors for SCD.

CONCLUSIONS

An ICD strategy is projected to yield the greatest increase in quality-adjusted life expectancy of the 3 treatment strategies evaluated. Combined consideration of age and the number of risk factors for SCD may allow more precise tailoring of ICD therapy to its expected benefits.

Documented exercise-induced cardiac arrest in a paediatric patient with hypertrophic cardiomyopathy

A paediatric patient with hypertrophic cardiomyopathy (HCM) presented cardiac arrest due to ventricular fibrillation. Ventricular arrhythmias were not induced in an electrophysiological study, but an implantable cardioverter defibrillator (ICD) was implanted. Nine months later, the child experienced a recurrence of cardiac arrest during exercise, which was successfully treated with a defibrillator shock from the device. Analysis of the stored electrograms demonstrated ventricular fibrillation of abrupt onset following sinus tachycardia. The risk factors and the potential mechanism leading to recurrent cardiac arrest in this case are discussed. This report supports implantation of an ICD as a life-saving therapeutic approach not only for adults but also for children with HCM at high risk.

Transcoronary ablation of septal hypertrophy does not alter ICD intervention rates in high risk patients with hypertrophic obstructive cardiomyopathy

INTRODUCTION

Transcoronary ablation of septal hypertrophy (TASH) is safe and effectively reduces the intraventricular gradient in patients with hypertrophic obstructive cardiomyopathy (HOCM). To analyze the potential of anti- and proarrhythmic effects of TASH, we studied the discharge rates of implanted cardioverter defibrillators (ICD) in patients with HOCM who are at a high risk for sudden cardiac death.

METHODS

ICD and TASH were performed in 15 patients. Indications for ICD-implantation were secondary prevention in nine patients after resuscitation from cardiac arrest with documented ventricular fibrillation (n = 7) or sustained ventricular tachycardia (n = 2) and primary prevention in 6 patients with a family history of sudden deaths, nonsustained ventricular tachycardia, and/or syncope. All the patients had severe symptoms due to HOCM (NYHA functional class = 2.9).

RESULTS

During a mean follow-up time of 41 +/- 22.7 months following the TASH procedure, 4 patients had episodes of appropriate discharges (8% per year). The discharge rate in the secondary prevention group was 10% per year and 5% in the group with primary prophylactic implants. Three patients died during follow-up (one each of pulmonary embolism, stroke, and sudden death).

CONCLUSION

In conclusion, on the basis of ICD-discharge rates in HOCM-patients at high risk for sudden death, there is no evidence for an unfavorable arrhythmogenic effect of TASH. The efficacy of ICD treatment for the prevention of sudden cardiac death in HOCM could be confirmed, however, mortality is high in this cohort of hypertrophic cardiomyopathy patients.

Cardioverter-defibrillator implantation in high-risk patients with hypertrophic cardiomyopathy

BACKGROUND

Implantable cardioverter-defibrillators (ICDs) are used with increasing frequency in hypertrophic cardiomyopathy (HCM) patients of all ages for primary and secondary sudden death prevention. Concerns may arise regarding the safety of device implantation because of unique clinical and phenotypic expressions of HCM.

OBJECTIVES

The purpose of this study was to assess the efficacy and safety of ICD placement in high-risk patients with HCM.

METHODS

We analyzed the experience with ICDs and transvenous lead systems in 75 consecutive HCM patients at the Minneapolis Heart Institute from 1993 to 2004.

RESULTS

The age of the study group patients was 12 to 79 years (mean 36 +/- 16). Patients received ICDs for secondary (n = 4, after cardiac arrest) or primary prevention (n = 71, with > or = 1 risk factor). Thirty-one patients demonstrated disease features that potentially impacted methodology and safety of the implant procedure, most commonly massive left ventricular (LV) hypertrophy and outflow obstruction > or = 50 mmHg. There were no procedure-related deaths; defibrillator implants were successful and uneventful in 71 of 75 patients (95%). In 3 of the 75 patients (4%), defibrillation was unsuccessful because of high thresholds, associated with extreme hypertrophy (wall thickness > 45 mm) and/or ongoing amiodarone therapy. In two of these patients, thoracotomy with epicardial lead placement achieved successful defibrillation; ICD therapy was abandoned in the other patient.

CONCLUSION

ICD placement in children and adults with HCM is generally safe and effective. However, in some patients with massive LV hypertrophy and/or prior administration of amiodarone, transvenous defibrillation proved difficult, and epicardial lead placement was required. High-energy ICD devices and defibrillation threshold testing are recommended for most high-risk HCM patients.

Efficacy of implantable cardioverter defibrillator therapy for primary and secondary prevention of sudden cardiac death in hypertrophic cardiomyopathy

Risk stratification and effectiveness of implantable cardioverter-defibrillator (ICD) therapy are unresolved issues in hypertrophic cardiomyopathy (HCM), a cardiac disease that is associated with arrhythmias and sudden death. We assessed ICD therapy in 132 patients with HCM: age at implantation was 34 +/- 17 years, and 44 (33%) patients were aged </= 20 years. Indications were sustained ventricular tachycardia (VT) or cardiac arrest (secondary prevention) in 47 (36%) patients, and clinical features associated with increased risk for sudden death (primary prevention) in 85 (64%) patients. There were 6 deaths and 55 appropriate interventions in 27 (20%) patients during a mean follow-up period of 4.8 +/- 4.2 years: 5-year survival and event-free rates were 96%+/- 2%and 75%+/- 5%, respectively. ICD intervention-free rates were significantly less for secondary than for primary prevention:64%+/- 7%versus 84%+/- 6%at 5 years,P = 0.02. Notably, 59 of 67 events (cardiac arrest and therapeutic ICD interventions), or 88%, occurred during sedentary or noncompetitive activity. Incidence of therapeutic shocks was related to age but not to other reported risk factors, including severity of cardiac hypertrophy, nonsustained VT during Holter monitoring, and abnormal blood pressure response to exercise. ICD related complications occurred in 38 (29%) patients, including 60 inappropriate ICD interventions in 30 (23%) patients. However, 8 (27%) of the patients with inappropriate shocks also had therapeutic interventions. ICD is effective for secondary prevention of sudden death in HCM. However, selection of patients for primary prevention of sudden death, and prevention of device related complications require further refinement.

Hypertrophic cardiomyopathy: management issues in the new millennium

Hypertrophic cardiomyopathy is an inherited cardiac disorder. Sudden cardiac death frequently occurs in otherwise healthy individuals, and accounts for nearly 35% of all sudden deaths within this age group. Although symptoms occur commonly, they often go unreported. Despite this, a degree of functional limitation is often seen on objective assessment. Management of hypertrophic cardiomyopathy is aimed at relieving symptoms, identifying and treating those individuals at increased risk of sudden death, and screening family members.

Risk stratification and prevention of sudden death in hypertrophic cardiomyopathy

Sudden unexpected death, often occurring in young, asymptomatic patients, is the most devastating facet of the natural history of hypertrophic cardiomyopathy, and appears to be the consequence of primary ventricular tachyarrhythmias arising in an electrically unstable myocardial substrate characterized by disorganized cellular architecture, ischemia, cell death, and replacement scarring. Although precise identification of all hypertrophic cardiomyopathy patients at high risk for a catastrophic event is a clinical challenge, effective treatment strategies for the prevention of sudden death with the implantable cardioverter-defibrillator are now available.

The role of pharmacologic treatment to prevent sudden death in the implantable cardioverter defibrillator era

The prevention of sudden death remains a key aspect of clinical management in patients with hypertrophic cardiomyopathy (HCM). For many years, amiodarone has been widely used to treat and prevent symptomatic atrial arrhythmias in patients with HCM, but its role in the prevention of potentially fatal ventricular arrhythmia has remained controversial. The publication of several observational studies examining the efficacy of implantable cardioverter defibrillators (ICDs) in patients with the disease has stimulated a re-evaluation of the drug's place in the management of HCM. This article reviews the literature on amiodarone therapy in HCM and discusses the indications for its use in the ICD era.

Ventricular tachycardia syndromes

Better understanding of the underlying mechanism and substrate of different VTs has made it possible to tailor treatment strategies properly. The advent of sophisticated device-based therapy and of more precise and effective catheter ablation approaches will expand clinicians' ability to gain control of this multifaceted arrhythmia syndrome.

Use of implantable pacemakers and implantable defibrillators in hypertrophic cardiomyopathy

Recent data have emerged to help guide the use of implantable pacemakers and implantable defibrillators in patients who have hypertrophic cardiomyopathy (HCM). Controlled studies of the use of dual chamber pacemakers to treat outflow tract obstruction in HCM have shown little benefit, and have raised the possibility that earlier favorable reports were demonstrating an element of placebo effect. In particular, there is no recent support for earlier claims of regression of ventricular hypertrophy from chronic dual chamber pacing. Several reports have added to our understanding of the risk factors for sudden death in HCM. A normal blood pressure response to exercise appears to identify a subset of patients at low risk for sudden death. In a recent study of a large number of HCM patients, the risk of sudden death was found to be directly proportional to the extent of left ventricular hypertrophy. There is accumulating evidence that the implantable defibrillator is highly effective in terminating malignant ventricular arrhythmias in HCM patients, and HCM patients thought to be at significant risk for sudden death should be offered defibrillator implantation.

Sudden death in hypertrophic cardiomyopathy: identification of high risk patients

OBJECTIVES

We sought to identify patients with hypertrophic cardiomyopathy (HCM) at high risk of sudden death (SD).

BACKGROUND

Relatively low mortality rates in HCM make conventional analysis of multiple clinical risk markers for SD problematic. This study used a referral center registry to investigate a smaller number of generally accepted noninvasive risk markers.

METHODS

We studied 368 patients (14 to 65 years old, 239 males) with HCM. There were five variables: nonsustained ventricular tachycardia (NSVT), syncope, exercise blood pressure response (BPR), family history of sudden death (FHSD) and left ventricular wall thickness (LVWT).

RESULTS

During follow-up (3.6+/-2.5 years [range 2 days to 9.6 years]), 36 patients (9.8%) died, 22 of them suddenly. Two patients received heart transplants. The six-year SD-free survival rate was 91% (95% confidence interval [CI] 87% to 95%). In the Cox model, there was a significant pairwise interaction between FHSD and syncope (p = 0.01), and these were subsequently considered together. The multivariate SD risk ratios (with 95% CIs) were 1.8 for BPR (0.7 to 4.4) (p = 0.22); 5.3 for FHSD and syncope (1.9 to 14.9) (p = 0.002); 1.9 for NSVT (0.7 to 5.0) (p = 0.18) and 2.9 for LVWT (1.1 to 7.1) (p = 0.03). Patients with no risk factors (n = 203) had an estimated six-year SD-free survival rate of 95% (95% CI 91% to 99%). The corresponding six-year estimates (with 95% CIs) for one (n = 122), two (n = 36) and three (n = 7) risk factors were 93% (87% to 99%), 82% (67% to 96%) and 36% (0% to 75%), respectively. Patients with two or more risk factors had a lower six-year SD survival rate (95% CI) compared with patients with one or no risk factors (72% [56% to 88%] vs. 94% [91% to 98%]) (p = 0.0001).

CONCLUSIONS

This study demonstrates that patients with multiple risk factors have a substantially increased risk of SD sufficient to warrant consideration for prophylactic therapy.

Defibrillator challenges for the new millennium: the marriage of device and patient-making and maintaining a good match

Although it has become clear that implantable cardioverter defibrillators (ICDs) are effective, important challenges remain for the physician. Due to the limitations of available risk stratification tools, patient selection for primary sudden death prevention remains controversial in many populations. Additionally, the proliferation of device choices has led to challenges in matching the appropriate device to the individual patient: device size is balanced against longevity; the advantages of dual chamber systems is weighed against their increased complexity; physician and patient preferences in device implant site are constrained by site-dependent effects on defibrillation effectiveness and lead failure rates; and special consideration must be given to the patient with a preexisting pacemaker. After ICD placement, determination of appropriate follow-up frequency and methodology to assess device function must be considered. This article will review patient selection, device implant site selection, device-device interactions, single versus dual chamber ICD selection, and follow-up.

[The clinical practice guidelines of the Sociedad Española de Cardiología on cardiomyopathies and myocarditis]

Myocardial diseases are a extraordinarily heterogeneous group of processes that only have in common the fact that they involve heart muscle and that they cause a wide spectrum of myocardial dysfunction. The approach of the management and treatment of the cardiomyopathies is a continuous matter of discussion because the vast majority of alternatives in this field have not been based on the best scientific possible evidence and, since except for the case of heart failure associated with dilated cardiomyopathy. The majority of different options have not been studied by means of large (or even small) randomized trials. Nevertheless, this chapter has tried to provide the reader with different approaches on how to deal with important clinical problems in dilated, hypertrophic and restrictive cardiomyopathies, and in myocarditis as well. For this, we have utilized the most relevant information found coupled with our best clinical judgment, although we admit that many of the clinical recommendations can be controversial.

Efficacy of implantable cardioverter-defibrillators for the prevention of sudden death in patients with hypertrophic cardiomyopathy

BACKGROUND

Hypertrophic cardiomyopathy is a genetic disease associated with a risk of ventricular tachyarrhythmias and sudden death, especially in young patients.

METHODS

We conducted a retrospective multicenter study of the efficacy of implantable cardioverter-defibrillators in preventing sudden death in 128 patients with hypertrophic cardiomyopathy who were judged to be at high risk for sudden death.

RESULTS

At the time of the implantation of the defibrillator, the patients were 8 to 82 years old (mean [+/-SD], 40+/-16), and 69 patients (54 percent) were less than 41 years old. The average follow-up period was 3.1 years. Defibrillators were activated appropriately in 29 patients (23 percent), by providing defibrillation shocks or antitachycardia pacing, with the restoration of sinus rhythm; the average age at the time of the intervention was 41 years. The rate of appropriate defibrillator discharge was 7 percent per year. A total of 32 patients (25 percent) had episodes of inappropriate discharges. In the group of 43 patients who received defibrillators for secondary prevention (after cardiac arrest or sustained ventricular tachycardia), the devices were activated appropriately in 19 patients (11 percent per year). Of 85 patients who had prophylactic implants because of risk factors (i.e., for primary prevention), 10 had appropriate interventions (5 percent per year). The interval between implantation and the first appropriate discharge was highly variable but was substantially prolonged (four to nine years) in six patients. In all 21 patients with stored electrographic data and appropriate interventions, the interventions were triggered by ventricular tachycardia or fibrillation.

CONCLUSIONS

Ventricular tachycardia or fibrillation appears to be the principal mechanism of sudden death in patients with hypertrophic cardiomyopathy. In high-risk patients with hypertrophic cardiomyopathy, implantable defibrillators are highly effective in terminating such arrhythmias, indicating that these devices have a role in the primary and secondary prevention of sudden death.

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.

What risk should justify implantable cardioverter defibrillator therapy?

Implantable cardioverter defibrillators (ICDs) were developed to prevent sudden cardiac death in patients with ventricular tachycardia (VT) or ventricular fibrillation (VF). Their safety and efficacy have been proved in multiple retrospective and prospective studies. Many of the published trials were directed at secondary prevention for patients who had already had a sudden cardiac death or a sustained VT. For primary prevention, the information available is limited, as only 2 trials have yet been published. Ongoing trials will probably allow us to broaden the indications for prophylactic ICD implantation. Justification of the risk will have to be evaluated against complexity of the implant, the latter including not only cost but quality of life and morbidity associated with an ICD. However, our efforts still have to be directed to improve risk stratification and to decrease the complexity of the procedure.

[Sudden death in hypertrophic myocardiopathy]

Hypertrophic cardiomyopathy is the most common cause of sudden death in young individuals who are otherwise healthy. Risk of sudden death is highest in patients who are between 14 and 35 years old. Several mechanisms are involved in sudden death: ventricular arrhythmias, supraventricular arrhythmias leading to cardiac collapse, bradycardias and severe ischemia. Many studies have analyzed how to identify high risk patients. The factors that best identify high risk patients are: previous history of sudden death or syncope, induction in adults of sustained ventricular arrhythmias, the presence of non-sustained ventricular tachycardia in symptomatic patients, the presence of ischemia associated with hypotension in children, the presence of mutations in the beta-myosin heavy chain together with a family history of sudden death and a poor left ventricular ejection fraction. Risk stratification should be done on an individualized basis. In those patients in whom a high risk for sudden arrhythmic death is suspected, the only current effective treatment is the implantable defibrillator.