Risk Of Sudden Arrhythmic Death Research Articles

Quantifying the origins of population variability in cardiac electrical activity through sensitivity analysis of the electrocardiogram

Altered function of ion channels in the heart can increase the risk of sudden arrhythmic death. Hundreds of genetic variants exist in these cardiac ion channel genes. The challenge is how to interpret the effects of multiple conductance perturbations on the complex multi-variable cardiac electrical system? In theory, sensitivity analysis can address this question. However, to date this approach has been restricted by computational overheads to analysis of isolated cells, which has limited extrapolation to physiologically relevant scales. The goal of this study was to extend existing sensitivity analyses to electrocardiogram (ECG) signals derived from multicellular systems and quantify the contribution of ionic conductances to emergent properties of the ECG. To achieve this, we have developed a highly parallelised simulation environment using unconventional high performance computing architectures to analyse the emergent electrical properties of a multicellular system. This has permitted the first systematic analysis of the molecular basis of the T wave amplitude, revealing important but distinct roles for delayed rectifier and inward rectifier K(+) currents. In addition to quantifying how interactions between multiple ion channels influence ECG parameters we show that these sensitivities are dynamic functions of heart rate. This study provides a significant advance in our understanding both of how individual ion conductances define ECG signals and of epistatic modification of cardiac electrical phenotypes. The parallelised simulation environment we have developed removes the computational roadblock that has limited this approach and so provides the framework for future analysis of more complex tissue and whole organ systems.

THE USE OF OMEGA-3 FATTY ACIDS FOR THE TREATMENT OF PATIENTS WITH CARDIAC ARRHYTHMIAS

Antiarrhythmic effect of omega-3 polyunsaturated fatty acids (ω-3 PUFA), eicosapentaenoic and docosahexaenoic acids in patients with recurrent atrial fibrillation and ventricular arrhythmias had been proven. The positive effect of the ω-3 PUFA on the risk of sudden arrhythmic death and overall mortality in the patients after myocardial infarction and patients with chronic heart failure had been also proven.

Implantable cardioverter defibrillator outcome: beyond ejection fraction?

This editorial refers to ‘Clinical markers of organ dysfunction associated with increased 1-year mortality post-implantable cardioverter defibrillator implantation’ by D. Chong et al ., on page 508 Over three decades of clinical experience have brought evidence that implantable cardioverter defibrillators (ICDs) should be considered as ‘gold standard’ therapy in prevention of sudden cardiac death. Implantable cardioverter defibrillators are currently indicated for secondary prevention in patients after cardiac arrest and life-threatening ventricular tachyarrhythmias or for primary prevention in patients considered at high risk of sudden arrhythmic death. The vast majority of ICDs for primary prevention are implanted in patients with significantly reduced left ventricular ejection fraction (LVEF) due to ischaemic or non-ischaemic cardiomyopathy. Although current eligibility for primary prevention ICD implantation is based merely on poor LVEF, we still experience an ongoing debate on how to identify patients who will benefit from ICD implantation. Furthermore, according to current guidelines, patients qualified for device implantation should have reasonable expectation of survival with a ‘good functional status’ for at least 1 year.1,2 Therefore, attempts are made to identify not only the ‘appropriate ICD candidate’, but also the one who may be ‘too sick’ to benefit from ICD therapy. The amount of benefit from an ICD is not uniform across the population eligible for ICD implantation, and may be limited due to early death from other than arrhythmic causes. Lack of survival benefit observed within the first year after implantation may be attributed to a higher risk of non-sudden death. Data from the MADIT II (Multicenter Automatic Defibrillator Implantation Trial), SCD-HeFT (Sudden Cardiac Death in heart Failure Trial), and DINAMIT (Defibrillation in Acute Myocardial Infarction Trial) studies demonstrated no separation of the Kaplan–Meier curves within the first 10–18 months after ICD implantation, suggesting that early mortality remains unaffected by ICD therapy. This …

QRS-T angle as a predictor of sudden cardiac death in a middle-aged general population

Spatial QRS-T angle measured from a 12-lead electrocardiogram (ECG) has been shown to predict cardiac mortality. However, there is a paucity of studies on the prognostic significance of frontal QRS-T angle, which is more readily available from the standard 12-lead ECG. The purpose of the present study was to investigate the importance of wide frontal QRS-T angle, QRS-axis, and T-wave axis as cardiac risk predictors in general population. We evaluated the 12-lead ECGs of 10 957 Finnish middle-aged subjects from the general population recorded between 1966 and 1972, and followed them for 30 ± 11 years. QRS-T angle 0 to 90°, QRS-axis -30 to 90°, and T-wave axis 0 to 90° were considered normal. The primary endpoint was death from arrhythmia, and the secondary endpoints were all-cause mortality and non-arrhythmic cardiac mortality. QRS-T angle ≥ 100° was present in 2.0% of the subjects, and it was associated with an increased risk of sudden arrhythmic death [relative risk (RR) 2.26; 95% confidence interval (CI) 1.59-3.21; P< 0.001) and all-cause mortality (RR 1.57; CI 1.34-1.84; P< 0.001), but not with non-arrhythmic cardiac mortality (RR 1.34; CI 0.93-1.92; P= 0.13). The prognostic significance of wide QRS-T angle was mainly due to abnormal T-wave axis, which predicted death from arrhythmia (RR 2.13; CI 1.63-2.79; P< 0.001), all-cause mortality (RR 1.39; 1.24-1.55; P< 0.001), and non-arrhythmic cardiac death (RR 1.87; CI 1.50-2.34; P< 0.001). Frontal QRS-T angle ≥ 100° increases the risk of arrhythmic death, this being mainly the result of an altered T-wave axis.

Characteristics of sudden arrhythmic death in a diverse, urban community

Sudden cardiac death (SCD) remains a major public health problem; however, its true burden remains unknown with widely variable estimates of its incidence. We aimed to examine the contemporary epidemiology and autopsy characteristics of SCD in an ethnically diverse community. Three physicians reviewed all deaths of individuals aged ≥20 years reported to the San Francisco medical examiner in 2007 for presentations fitting World Health Organization (WHO) SCD criteria-within 1 hour of symptom onset (witnessed) or within 24 hours of being observed alive and symptom free (unwitnessed). After comprehensive review of medical examiner investigation, WHO SCDs were classified as sudden arrhythmic death (SAD) or nonarrhythmic death. Coronary artery disease (CAD) and cardiac mass were evaluated in all SADs undergoing autopsy and compared with demographically similar accidental trauma control deaths. We identified 252 WHO SCDs; 145 were SADs. Men had a 2.2-fold higher SAD rate (P < .0005). Blacks had a 3.15-fold higher SAD rate compared with whites (P = .003). Significant CAD was present in 38.9% of SADs and associated with higher SAD risk compared with control deaths (OR 2.58, 95% CI 1.12-5.97, P = .026). Mean cardiac mass was linearly associated with risk for SAD in cases without significant CAD (OR 2.06 per 100 g, 95% CI 1.43-2.98, P < .0005). In a diverse, urban population, SAD incidence varied substantially by gender and race. Significant CAD accounted for far fewer SADs than previous studies but remained associated with a 2.6-fold higher risk as compared with control deaths. These findings may reflect the evolving contemporary epidemiology of SCD.

Abstract 8649: Aerobic Exercise Training Improves Heart Rate Variability, as Reflected by PD2i, in Individuals with Low PD2i

Point Correlation Dimension (PD2i) is a non-linear measure of heart rate variability complexity that has been shown to be able to predict the risk of sudden arrhythmic death, such that a value ≤ 1.4 increases risk substantially, with a value ≤2 denoting the presence of autonomic dysfunction. It is unclear, however, if exercise, a lifestyle behavior recommended to sedentary individuals, can favorably alter PD2i. The purpose of this study was to determine if 16 weeks of moderate intensity aerobic exercise training would raise PD2i in sedentary lean and obese, middle aged men and women (age 40-57 yr). PD2i was measured at rest and in response to 5 min of upright tilt pre and post the 16 week exercise training regimen. Subjects were stratified into 2 groups according to their pre-regimen resting PD2i: low PD2i≤ 2 (lPD2i, n=14) and normal PD2i &gt;2 (nPD2i, n=45 ). At rest, there was a training by group interaction such that PD2i increased substantially with exercise training in the lPD2i group but not in the nPD2i group (lPD2i pre 1.94±0.2, post 2.46±0.2; nPD2i pre 2.95±0.1, post 3.0±0.09, P=0.02). In response to the sympathetic stress of upright tilt (known to acutely lower PD2i), both groups had an appropriate decrease in PD2i (P&lt;0.001) and an overall effect of training (P=0.04), but there was no training by group interaction on this response. During recovery from tilt, the lPD2i group had a significant improvement in PD2i with training (lPD2i pre 2.21±0.2, post 2.92±0.2; nPD2i pre 3.26±0.1, post 3.22±0.1, P=0.009), while there was no change in the nPD2i group. In conclusion, a 16 wk moderate intensity training program improves resting and recovery PD2i in those with low initial resting values, and this improvement may reduce their risk of sudden arrhythmic death.

Spatial vectorcardiogram to predict risk for sudden arrhythmic death: Phoenix risen from the ashes

Two developments of the latter part of the twentieth century have generated a vigorous and continuing quest for reliable predictors of sudden arrhythmic deaths.1,2 First was the recognition of the great magnitude of the numbers of victims of sudden death due to ventricular tachyarrhythmias, constituting the majority of sudden cardiac deaths. The second was the development of an effective preventive therapy, the automatic implantable cardioverter-defibrillator (ICD).3 The first attempt to predict and prevent sudden arrhythmic death was based on pharmacotherapy and produced the shocking result that the preventive treatment increased rather than decreased mortality.

T-wave alternans testing: Can it predict arrhythmogenesis?

Sudden cardiac death (SCD) resulting from ventricular arrhythmias causes almost 300,000 deaths annually in the United States. 1 Rubart M. Zipes D.P. Mechanisms of sudden cardiac death. J Clin Invest. 2005; 115: 2305-2315 Crossref PubMed Scopus (384) Google Scholar With the disappointing performance of antiarrhythmic drugs, the implantable cardioverter-defibrillator (ICD) has emerged as the primary therapy for preventing SCD. 2 Prystowsky E.N. Prevention of sudden cardiac death. Clin Cardiol. 2005; 28: I12-I18 PubMed Google Scholar However, a major challenge that needs to be addressed is the identification of patients at highest risk for SCD, as ICD placement is expensive, and the majority of the devices never deliver shocks. 3 Armoundas A.A. Hohnloser S.H. Ikeda T. Cohen R.J. Can microvolt T-wave alternans testing reduce unnecessary defibrillator implantation?. Nat Clin Pract Cardiovasc Med. 2005; 2: 522-528 Crossref PubMed Scopus (33) Google Scholar Use of several strategies—either invasive measurements, such as electrophysiologic study (EPS), or noninvasive measurements, such as left ventricular ejection fraction (LVEF), heart rate variability, signal-averaged electrocardiogram, QT dispersion, magnetic resonance imaging, and T-wave alternans (TWA)—are now being investigated for better stratification of patients at risk for arrhythmogenesis. 4 Huikuri H.V. Mäkikallio T.H. Raatikainen M.J. Perkiömäki J. Castellanos A. Myerburg R.J. Prediction of sudden cardiac death: appraisal of the studies and methods assessing the risk of sudden arrhythmic death. Circulation. 2003; 108: 110-115 Crossref PubMed Scopus (151) Google Scholar , 5 Villuendas R. Kadish A.H. Cardiac magnetic resonance for risk stratification: the sudden death risk portrayed. Prog Cardiovasc Dis. 2008; 51: 128-134 Abstract Full Text Full Text PDF PubMed Scopus (5) Google Scholar

A Common Single Nucleotide Polymorphism Can Exacerbate Long-QT Type 2 Syndrome Leading to Sudden Infant Death

Identification of infants at risk for sudden arrhythmic death remains one of the leading challenges of modern medicine. We present a family in which a common polymorphism (single nucleotide polymorphism) inherited from the father, combined with a stop codon mutation inherited from the mother (both asymptomatic), led to 2 cases of sudden infant death. KCNQ1, KCNH2, SCN5A, KCNE1, KCNE2, CACNA1c, CACNB2b, and KCNJ2 genes were amplified and analyzed by direct sequencing. Functional electrophysiological studies were performed with the single nucleotide polymorphism and mutation expressed singly and in combination in Chinese ovary (CHO-K1) and COS-1 cells. An asymptomatic woman presenting after the death of her 2-day-old infant and spontaneous abortion of a second baby in the first trimester was referred for genetic analysis. The newborn infant had nearly incessant ventricular tachycardia while in utero and a prolonged QTc (560 ms). The mother was asymptomatic but displayed a prolonged QTc. Genetic screening of the mother revealed a heterozygous nonsense mutation (P926AfsX14) in KCNH2, predicting a stop codon. The father was asymptomatic with a normal QTc but had a heterozygous polymorphism (K897T) in KCNH2. The baby who died at 2 days of age and the aborted fetus inherited both K897T and P926AfsX14. Heterologous coexpression of K897T and P926AfsX14 led to loss of function of HERG current much greater than expression of K897T or P926AfsX14 alone. Our data suggest that a common polymorphism (K897T) can markedly accentuate the loss of function of mildly defective HERG channels, leading to long-QT syndrome-mediated arrhythmias and sudden infant death.

Bridging a Temporary High Risk of Sudden Arrhythmic Death. Experience with the Wearable Cardioverter Defibrillator (WCD)

The implantable cardioverter defibrillator (ICD) is able to reduce sudden arrhythmic death in patients who are considered to be at high risk. However, the arrhythmic risk may be increased only temporarily as long as the proarrhythmic conditions persist, left ventricular ejection fraction remains low, or heart failure prevails. The wearable cardioverter defibrillator (WCD) represents an alternative approach to prevent sudden arrhythmic death until either ICD implantation is clearly indicated or the arrhythmic risk is considered significantly lower or even absent. The WCD is also indicated for interrupted protection by an already implanted ICD, temporary inability to implant an ICD, and lastly refusal of an indicated ICD by the patient. The WCD is not an alternative to the ICD, but a device that may contribute to better selection of patients for ICD therapy. The WCD has the characteristics of an ICD, but does not need to be implanted, and it has similarities with an external defibrillator, but does not require a bystander to apply lifesaving shocks when necessary. The WCD was introduced into clinical practice about 8 years ago, and indications for its use are currently expanding. This article describes the technological aspects of the WCD, discusses current indications for its use, and reviews the clinical studies with the WCD. Additionally, data are reported on the clinical experience with the WCD based on 354 patients from Germany hospitalized between 2000 and 2008 who wore the WCD for a mean of 3 months.

The Wearable Cardioverter Defibrillator-Bridge to the Implantable Defibrillator.

The wearable cardioverter defibrillator (WCD) was introduced into clinical practice about 8 years ago as an alternative approach to protect patients with a temporary high risk of sudden arrhythmic death. The WCD has the characteristics of an implantable defibrillator (ICD) but does not need to be implanted, and it has similarities with an external defibrillator, but does not require a bystander to apply lifesaving shocks when necessary. Based on current clinical experience, the WCD is not analternative to the ICD, but a device that will contribute to better selection of patients for ICD therapy and may be indicated in case of interrupted protection by an already implanted ICD, temporary inability to implant an ICD, or refusal of an indicated ICD.

Marine polyunsaturated fatty acids in heart failure Are the theoretical benefits matched by the clinical data?

Chronic heart failure (CHF) is a common condition, which despite major advances, is still characterized by high mortality (with sudden arrhythmic death a particular risk), poor quality of life due to exercise intolerance and frequent hospitalizations. Epidemiological studies suggest that populations with a high intake of marine polyunsaturated fatty acids (PUFAs or fish oils) have low levels of cardiovascular mortality. Animal and human studies of fish oil supplementation have demonstrated improved endothelial function and myocardial relaxation, reduced vascular tone and platelet aggregability, and a stabilization of myocyte excitability by prolongation of the refractory period. Marine PUFAs also have potentially important immune-modulating effects, reducing cytokine production and release, and altering prostaglandin metabolism. Data from patients following acute myocardial infarction have suggested that marine PUFA supplementation may reduce early mortality, mostly by reducing the risk of sudden arrhythmic death. Until recently, data in patients with chronic heart failure was lacking, but the recent publication of the GISSI-HF study, randomizing more than 7000 CHF patients to marine PUFA supplementation or placebo has clarified somewhat the role of these agents. The aim of this article is to review the theoretical benefits of marine PUFAs and to discuss the implications of the GISSI-HF study for the management of patients with CHF.

Risk stratification for arrhythmic death in an emergency department cohort: a new method of nonlinear PD2i analysis of the ECG

Heart rate variability (HRV) reflects both cardiac autonomic function and risk of sudden arrhythmic death (AD). Indices of HRV based on linear stochastic models are independent risk factors for AD in postmyocardial infarction (MI) cohorts. Indices based on nonlinear deterministic models have a higher sensitivity and specificity for predicting AD in retrospective data. A new nonlinear deterministic model, the automated Point Correlation Dimension (PD2i), was prospectively evaluated for prediction of AD. Patients were enrolled (N = 918) in 6 emergency departments (EDs) upon presentation with chest pain and being determined to be at risk of acute MI (AMI) >7%. Brief digital ECGs (>1000 heartbeats, approximately 15 min) were recorded and automated PD2i results obtained. Out-of-hospital AD was determined by modified Hinkle-Thaler criteria. All-cause mortality at 1 year was 6.2%, with 3.5% being ADs. Of the AD fatalities, 34% were without previous history of MI or diagnosis of AMI. The PD2i prediction of AD had sensitivity = 96%, specificity = 85%, negative predictive value = 99%, and relative risk >24.2 (p ≤ 0.001). HRV analysis by the time-dependent nonlinear PD2i algorithm can accurately predict risk of AD in an ED cohort and may have both life-saving and resource-saving implications for individual risk assessment.

A 59-Year-Old Man Considering Implantation of a Cardiac Defibrillator

Nearly 450,000 individuals experience sudden cardiac death yearly in the United States. A history of prior myocardial infarction with resultant left ventricular dysfunction identifies a group at particularly high risk of sudden arrhythmic death. Implantable cardioverter-defibrillators have proven highly effective at reducing this risk and are now increasingly implanted in patients with this risk profile. The case of Mr M, a 59-year-old man with a history of myocardial infarction, low ejection fraction, and mild congestive heart failure, who is considering implantable cardioverter-defibrillator placement, illustrates the issues in having a device implanted as a prophylactic measure as well as increasing concerns due to device recalls and malfunction. A thorough discussion of the benefits and risks associated with this therapy is necessary for patients and physicians to make appropriate decisions with regard to the primary prevention of sudden death.

Cardiac Resynchronization Therapy: A Review of Proarrhythmic and Antiarrhythmic Mechanisms

Available evidence supports the hypothesis that cardiac resynchronization therapy (CRT) results in favorable structural as well as electrical remodeling. Electrical remodeling seems to be related, to a large extent, to structural remodeling, usually referred to as reverse remodeling of left ventricular (LV) dysfunction. This can lead to amelioration of the arrhythmogenic substrate associated with depressed LV systolic function and heart failure. However, a direct electrophysiological effect due to favorable remodeling of repolarization with reduction of the dispersion of repolarization cannot be ruled out. On the other hand, in a small subgroup of patients, CRT could increase the dispersion of repolarization and induce malignant ventricular tachyarrhythmias. Clinical trials have consistently shown improved outcome with CRT-defibrillators (CRT-D) and more trials have demonstrated the benefits of the defibrillator in the population with depressed LV function. However, some physicians argue that implanting the less expensive and less complicated CRT-pacemaker (CRT-P) may be appropriate in certain groups of patients. Before this position is accepted, it is imperative that criteria for the selection of this group of patients with presumably low risk for sudden arrhythmic death as well as the proarrhythmic effect of CRT be clearly defined.

Exercise Testing in Wolff-Parkinson-White Syndrome: Case Report With ECG and Literature Review

AbstractECG changes during exercise stress testing, such as false-positive ST-segment depression and disappearance of the delta wave, are reported in patients with the Wolff-Parkinson-White (WPW) pattern. We present a case of exercise testing in a 53-year-old man with WPW syndrome with ischemic-appearing ECG changes and normal nuclear stress perfusion study findings who was thought to be at clinically low risk for having significant coronary disease. A literature review is discussed. Although ST-segment depression typical for ischemia occurs in half of the patients in whom WPW syndrome is reported, exercise testing is still an important tool in their evaluation. Data other than ECG response can be interpreted in the context of clinical history and physical examination findings to stratify the risk of coronary disease. Complete and sudden disappearance of the delta wave has been seen during exercise in 20% of patients with WPW syndrome and can identify those who are at low risk for sudden arrhythmic death

Exercise Testing in Wolff-Parkinson-White Syndrome*

ECG changes during exercise stress testing, such as false-positive ST-segment depression and disappearance of the delta wave, are reported in patients with the Wolff-Parkinson-White (WPW) pattern. We present a case of exercise testing in a 53-year-old man with WPW syndrome with ischemic-appearing ECG changes and normal nuclear stress perfusion study findings who was thought to be at clinically low risk for having significant coronary disease. A literature review is discussed. Although ST-segment depression typical for ischemia occurs in half of the patients in whom WPW syndrome is reported, exercise testing is still an important tool in their evaluation. Data other than ECG response can be interpreted in the context of clinical history and physical examination findings to stratify the risk of coronary disease. Complete and sudden disappearance of the delta wave has been seen during exercise in 20% of patients with WPW syndrome and can identify those who are at low risk for sudden arrhythmic death.

Risk stratification and epidemiology of sudden death.

Recent data from the Centers for Disease Control and Prevention show that sudden cardiac death accounts for approximately 400,000 deaths annually in this country. The survival rate for these patients is dismal. Because of the low probability of survival from a cardiac arrest, there has been an increasing focus on primary prevention. The implantable cardioverter defibrillator (ICD) is a highly effective treatment to abort potentially fatal arrhythmic episodes. Thus, various trials have been conducted to determine methods to best identify patients at high risk for sudden arrhythmic death. This review focuses on the epidemiology of sudden cardiac death and risk stratification approaches that have been tested to determine whether they can identify populations likely to benefit from an ICD.

Microvolt T-wave alternans as predictor of electrophysiological testing results in professional competitive athletes.

Several studies have confirmed the equivalence of the microvolt T-wave alternans (mTWA) and the electrophysiology (EPS) tests in cardiac disease. No data are available in populations of competitive athletes with arrhythmias that might jeopardize the pursuit of their professional career. We prospectively studied 100 trained competitive athletes, including elite types (72/100), (mean age +/- standard deviation: 26.1 +/- 4.5 years). Forty-eight of them were wholly normal (Group A, mean age: 24.5 +/- 8.5 years) and 52 of them had severe arrhythmias (Group B, mean age: 28.2 +/- 11.5 years) and were symptomatic in 85% of cases for prolonged palpitations and syncope, but lacked any overt structural heart disease at standardized cardiological screening. All athletes were evaluated with the microvolt T-wave alternans exercise-stress test, using the Heart Wave System with Microvolt Sensors. Group B underwent EPS to evaluate inducibility to sustained ventricular tachycardia (VT) during programmed electrical stimulation. In Group A, the mTWA outcome was determinate in 45 subjects (94%) and indeterminate in 3 (6%). No symptomatic event was reported in a follow-up of 36.1 months. In Group B, the mTWA test was positive in 7 symptomatic subjects (15%), indeterminate in 3 (7%), and negative for the remaining 42 subjects (76%). Forty-one of 42 negative mTWA subjects were also negative in the EPS test, without any syncope or sustained VT during 25.3 months of follow-up. In the positive mTWA test subjects, 5 (72%) were positive for inducibility of rapid sustained monomorphic VT in EPS, 1 was positive for severe sustained atrial tachyarrhythmias, and 1 refused EPS. We were able to pronounce a correct diagnosis of lymphocytic myocarditis for only 1 mTWA and EPS-positive subject. For the other 4 positive patients with arrhythmogenic micropathology, severe arrhythmic events were revealed in the follow-up and aggressive hybrid treatment was necessary. Microvolt-TWA study seems to be a useful, noninvasive, and feasible tool for evaluating arrhythmic risk in the athletic population. The mTWA test showed a high negative predictive value, using both EPS and the follow-up observation for severe arrhythmic cardiac events as an endpoint. The positive predictive value was present in a limited number of cases that were, however, subjects with a high risk of sudden arrhythmic death.

Hypertrophic cardiomyopathy: state‐of‐the‐art review, with focus on the management of outflow obstruction

Significant advances in our understanding and management of hypertrophic cardiomyopathy have been made in the last decade, as the complex genetics and phenotype-genotype correlations that characterize the disease are gradually unravelled. The well-described clinical heterogeneity of hypertrophic cardiomyopathy is now understood to be based on profound genetic variability, with at least 10 genes and over 150 mutations implicated. Several new therapeutic tools have entered clinical practice. The implantable cardioverter-defibrillator is now strongly indicated in those at high risk of sudden arrhythmic death. Our ability to abort sudden death in this subgroup has placed added emphasis on risk stratification in newly diagnosed patients. New procedures have also been developed for the relief of outflow obstruction in patients with refractory symptoms and a significant subaortic outflow gradient. Although not as efficacious as the 'gold-standard' surgical myectomy-myotomy, dual-chamber pacemaker implantation can be of modest benefit in select patients. Percutaneous transluminal septal myocardial ablation is an emerging catheter-based procedure for the relief of left ventricular outflow obstruction. Long-term follow-up data are still awaited. However, intermediate-term results suggest equivalent efficacy to surgical myectomy-myotomy.