ACC/AHA/ESC 2006 Guidelines for Management of Patients With Ventricular Arrhythmias and the Prevention of Sudden Cardiac Death—Executive Summary: A Report of the American College of Cardiology/American Heart Association Task Force and the European Society of Cardiology Committee for Practice Guidelines (Writing Committee to Develop Guidelines for Management of Patients With Ventricular Arrhythmias and the Prevention of Sudden Cardiac Death): Developed in Collaboration With the European Heart Rhythm Association and the Heart Rhythm Society

[Forensic expert evaluation problems of early and late complications of interventional methods of treating coronary heart disease (systematic literature review)]

This article focuses on current concepts of ischemic heart disease, its interventional treatment, pathomorphology of early and late postoperative complications, and forensic aspects in evaluation of restenosis of a stented blood vessel.

[Molecular genetic basis of sudden cardiac death in the young with cardiomyopathy of various origins]

This paper provides a review of the modern literature devoted to the problem of forensic medical interpretation of the molecular genetic research of the young who died suddenly. The authors attempted to draw a parallel between the morphological markers of different variants of cardiomyopathy as the most common disease in sudden death at a young age and the association with genetic mutations in the genes responsible for the synthesis of sarcomer proteins, desmos and membrane channels. Based on the results of the analysis, further research is proposed to improve the accuracy of forensic diagnosis in cases of young deaths.

Acquired Long QT Syndrome and Electrophysiology of Torsade de Pointes

Congenital long QT syndrome (LQTS) has been the most investigated cardiac ion channelopathy. Although congenital LQTS remains the domain of cardiologists, cardiac electrophysiologists and specialised centres, the much more frequently acquired LQTS is the domain of physicians and other members of healthcare teams required to make therapeutic decisions. This paper reviews the electrophysiological mechanisms of acquired LQTS, its ECG characteristics, clinical presentation, and management. The paper concludes with a comprehensive review of the electrophysiological mechanisms of torsade de pointes.

Bayesian Classification Models for Premature Ventricular Contraction Detection on ECG Traces

According to the American Heart Association, in its latest commission about Ventricular Arrhythmias and Sudden Death 2006, the epidemiology of the ventricular arrhythmias ranges from a series of risk descriptors and clinical markers that go from ventricular premature complexes and nonsustained ventricular tachycardia to sudden cardiac death due to ventricular tachycardia in patients with or without clinical history. The premature ventricular complexes (PVCs) are known to be associated with malignant ventricular arrhythmias and sudden cardiac death (SCD) cases. Detecting this kind of arrhythmia has been crucial in clinical applications. The electrocardiogram (ECG) is a clinical test used to measure the heart electrical activity for inferences and diagnosis. Analyzing large ECG traces from several thousands of beats has brought the necessity to develop mathematical models that can automatically make assumptions about the heart condition. In this work, 80 different features from 108,653 ECG classified beats of the gold-standard MIT-BIH database were extracted in order to classify the Normal, PVC, and other kind of ECG beats. Three well-known Bayesian classification algorithms were trained and tested using these extracted features. Experimental results show that the F1 scores for each class were above 0.95, giving almost the perfect value for the PVC class. This gave us a promising path in the development of automated mechanisms for the detection of PVC complexes.

Combined effect of renal function and serum potassium level in sudden cardiac death in aging hypertensive subjects

In patients with chronic kidney disease, serum potassium level is a factor influencing sudden cardiac death (SCD). The aim of our analysis was to study the combined effect of serum potassium level and renal function on the onset of SCD in elderly hypertensive subjects. Data from the 3620 hypertensive patients aged over 70 years were extracted from three randomized clinical trials included in the INDANA database. During a mean follow up of 4.5 years, 81 patients (2.24%) died from SCD. Mean serum potassium levels and prevalence of chronic kidney disease were not different in patients who died from SCD. In addition to serum potassium and creatinine levels, 14 clinical and biological variables linked to cardiovascular diseases recorded at baseline were analyzed using a Bayesian network. The area under the receiver operating characteristic curve of the Bayesian model reached 0.91. Bayesian inference was used to simulate the combined effects of serum potassium and creatinine levels on SCD. Our analysis, using simulated data from Bayesian model, showed that the estimated probabilities of SCD was significantly increased in case of hyperkalemia (>5.0 mmol/l) and in case of hypokalemia (<3.5 mmol/l) and in case of chronic kidney disease. Combined effects of serum potassium level and renal function revealed that chronic kidney disease increased the probability of SCD whatever the serum potassium level. Our results using a Bayesian model confirm the deleterious effects of hypokalemia, hyperkalemia and chronic kidney disease on SCD in elderly hypertensive patients.

Beneficial Effects of Isoproterenol and Quinidine in the Treatment of Ventricular Fibrillation in Brugada Syndrome

The use of an implantable cardiac defibrillator has been advocated as the only effective treatment for the management of ventricular fibrillation (VF) in patients with Brugada Syndrome (BrS). However, this device is only useful for terminating VF. Intermittent and/or recalcitrant VF for which lifesaving cardioversion occurs is a problematic situation in this patient population. The immediate use of appropriate antiarrhythmics in the acute setting has proven to be lifesaving. Quinidine has been well established as an effective antiarrhythmic in BrS, while isoproterenol (ISP) has had some recognition as well. The addition of drug therapy to prevent the induction of these arrhythmias has been shown to reduce the morbidity and mortality associated with BrS. It was proven to be especially effective in the presence of early repolarization, evidenced by the reduction or normalization of the early repolarization pattern on ECG. Thus, for the prophylactic management and long term suppression of VF in BrS, further prospective studies should be performed to determine the effectiveness of quinidine and ISP in this patient population.

Lower omega-3 index is a marker of increased propensity of hypertensive rat heart to malignant arrhythmias

Polyunsaturated omega-3 fatty acids (omega-3 PUFA) are important components of cell membrane affecting its function and their deficiency is deleterious to health. We have previously shown that spontaneously hypertensive rats (SHR) are prone to life-threatening arrhythmias that are reduced by omega-3 PUFA intake. Purpose of this study was to explore plasma and red blood cells (RBC) profile of omega-3 and omega-6 PUFA as well as to determine omega-3 index, a risk factor for sudden cardiac death, in aged SHR and the effect of omega-3 PUFA intake. Male and female 12-month-old SHR and age-matched Wistar rats fed with omega-3 PUFA (200 mg/kg BW/day/2 month) were compared with untreated rats. Composition of omega-3 PUFA: alpha linolenic acid, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) as well as omega-6 PUFA: linoleic acid and arachidonic acid was analyzed by gas chromatography. Results showed sex- and strain-related differences of basal omega-3 and omega-6 PUFA levels in plasma and RBC as well as in response to omega-3 PUFA intake. Comparing to Wistar rats omega-3 index, expressed as a percentage of EPA+DHA of total fatty acids, was lower in SHR and it increased due to consumption of omega-3 PUFA. Findings support our hypothesis that lower omega-3 index may be also a marker of increased propensity of the hypertensive rat heart to malignant arrhythmias.

Economic burden and disparities in healthcare resource use among adult patients with cardiac arrhythmia

BACKGROUND

As of 2012, approximately 4.3 million Americans experience some form of cardiac arrhythmia (CA). Assessment of economic burden and healthcare resource use on the overall CA population is limited.

OBJECTIVES

To assess healthcare expenditure and disparities in healthcare resource use in patients with all forms of CA in the US.

METHODS

Data from the Medical Expenditure Panel Survey were analyzed between 2004 and 2009. Patients aged≥18 years with any form of CA (identified via International Classification of Disorders Ninth Revision, Clinical Modification [ICD-9-CM] codes) were included. Primary independent variables included age, gender, race/ethnicity, and pharmacotherapy use. Outcomes of interest included total annual healthcare and prescription expenditures (inflation adjusted to 2011), use of anti-arrhythmic agents associated with CA, and inpatient, outpatient, or emergency room visits. Generalized linear models were used to assess the disparities across patient subgroups related to the outcomes.

RESULTS

Annually, 5,750,440 individuals experienced CA in the US. Total direct annual healthcare cost of CA summed up to $US67.4 billion. Non-Hispanic whites and older adult patients had higher expenditures and use of healthcare resources (p<0.05). Female patients had significantly higher prescribed medication expenditures and a lower proportion of inpatient and emergency room visits related to arrhythmia (p<0.05). Patients taking anti-arrhythmic agents had significantly higher expenditure and a lower proportion of emergency department visits related to arrhythmia (p<0.05).

CONCLUSIONS

CA represents a substantial economic burden in the US, especially for the older adult population. Patients other than non-Hispanic whites may not have adequate access to healthcare treatment for arrhythmia.

Syncope in adults: systematic review and proposal of a diagnostic and therapeutic algorithm

This review aims to provide a practical and up-to-date description on the relevance and classification of syncope in adults as well as a guidance on the optimal evaluation, management and treatment of this very common clinical and socioeconomic medical problem. We have summarized recent active research and emphasized the value for physicians to adhere current guidelines. A modern management of syncope should take into account 1) use of risk stratification algorithms and implementation of syncope management units to increase the diagnostic yield and reduce costs; 2) early implantable loop recorders rather than late in the evaluation of unexplained syncope; and 3) isometric physical counter-pressure maneuvers as first-line treatment for patients with neurally-mediated reflex syncope and prodromal symptoms.

New familial heterozygous c 4066_4068 delTT 2 bp deletion of the SCN5A gene causing Brugada syndrome

BACKGROUND

Cardiac sodium channel alterations have been identified as the underlying condition in patients with Brugada syndrome.

OBJECTIVE

This study identified a novel mutation of the SCN5A gene in a family with Brugada syndrome.

METHODS

Blood was drawn from the children and mother for genetic analysis. All exons of the SCN5A gene were amplified by polymerase chain reaction, and a sequence analysis was performed.

RESULTS

The mutation was detected in 1 symptomatic and 2 asymptomatic family members. The deletion of base 4066_4068delTT leads to a shift in the amino acid sequence and a premature stop of the protein translation. The clinical diagnosis of Brugada syndrome in this family was supported by the detection of the new mutation.

CONCLUSION

We describe a family partly with Brugada syndrome and a novel mutation in the exon 23 of the SCN5A gene leading to a deletion of 2 thymidine bases. This mutation results in an early termination of the encoded protein and possibly in a nonfunctional channel protein.

QTc prolongation during therapeutic hypothermia: are we giving it the attention it deserves?

AIMS

Therapeutic hypothermia (TH) is used in neuroprotection following cardiac arrest due to ventricular tachycardia (VT) and ventricular fibrillation (VF). Accidental hypothermia is itself known to cause prolongation of the corrected QT interval (QTc). QTc prolongation can cause polymorphic VT and VF. If this also occurs in TH, it may induce refibrillation. We investigated the effect of TH on the QTc interval.

METHODS AND RESULTS

Prospective case series of all patients undergoing TH following cardiac arrest following VT/VF at our hospital between July 2008 and January 2009. We studied the effect of temperature on QTc. All electrocardiograms (ECGs) undertaken during TH were studied and compared with the ECG prior to this. Four patients underwent TH. A total of 10 ECGs were undertaken during TH. The QTc was normal prior to TH. It became prolonged (>460 ms) in all cases during TH and normalized after cessation of TH, apart from Patient 4 who did not have an ECG post-TH since she died from cardiogenic shock. There was a negative correlation between temperature and QTc (Pearson's correlation coefficient, r= -0.71).

CONCLUSION

Our series illustrates QTc prolongation during TH. This carries potential for refibrillation. Guidelines on ECG monitoring during TH are needed, especially since hypothermic myocardium is intrinsically prone to arrhythmias and commonly used antiarrythmic drugs such as amiodarone can prolong the QTc.

Towards a better risk stratification for sudden cardiac death in patients with structural heart disease

With the introduction of the implantable cardioverter defibrillator (ICD), patients can be protected against sudden cardiac death (SCD) due to ventricular arrhythmia (VA). Guidelines have been drawn up for selecting patients for primary and secondary prophylaxis. However, most ICD recipients today who receive an ICD for primary prevention will not experience a life-threatening VA requiring antitachypacing or shock therapy. Better risk stratification is desirable with efficacy, costs and complication rate in mind. An overview is presented of widely accepted and potentially valuable risk markers and the role they may play in better identifying candidates for ICD therapy. (Neth Heart J 2009;17:101-6.).

A KCNH2 branch point mutation causing aberrant splicing contributes to an explanation of genotype-negative long QT syndrome

BACKGROUND

Genetic screening of long QT syndrome (LQTS) fails to identify disease-causing mutations in about 30% of patients. So far, molecular screening has focused mainly on coding sequence mutations or on substitutions at canonical splice sites.

OBJECTIVE

The purpose of this study was to explore the possibility that intronic variants not at canonical splice sites might affect splicing regulatory elements, lead to aberrant transcripts, and cause LQTS.

METHOD

Molecular screening was performed through DHPLC and sequence analysis. The role of the intronic mutation identified was assessed with a hybrid minigene splicing assay.

RESULTS

A three-generation LQTS family was investigated. Molecular screening failed to identify an obvious disease-causing mutation in the coding sequences of the major LQTS genes but revealed an intronic A-to-G substitution in KCNH2 (IVS9-28A/G) cosegregating with the clinical phenotype in family members. In vitro analysis proved that the mutation disrupts the acceptor splice site definition by affecting the branch point (BP) sequence and promoting intron retention. We further demonstrated a tight functional relationship between the BP and the polypyrimidine tract, whose weakness is responsible for the pathological effect of the IVS9-28A/G mutation.

CONCLUSIONS

We identified a novel BP mutation in KCNH2 that disrupts the intron 9 acceptor splice site definition and causes LQT2. The present finding demonstrates that intronic mutations affecting pre-mRNA processing may contribute to the failure of traditional molecular screening in identifying disease-causing mutations in LQTS subjects and offers a rationale strategy for the reduction of genotype-negative cases.

A KCNQ1 V205M missense mutation causes a high rate of long QT syndrome in a First Nations community of northern British Columbia: a community-based approach to understanding the impact

PURPOSE

Hereditary long QT syndrome is named for a prolonged QT interval reflecting predisposition to ventricular arrhythmias and sudden death. A high rate in a remote, northern Canadian First Nations community was brought to attention.

METHODS

Two severely affected index cases and 122 relatives were ascertained using community-based participatory research principles. Genetic sequencing of five known genes responsible for long QT syndrome was carried out on the index cases, leading to the identification of a novel missense mutation. Functional properties of the identified mutation were studied in transfected mouse ltk- cells using whole cell patch clamp techniques. Corrected QT interval measurements were obtained from participants and subsequent genotyping of relatives was carried out.

RESULTS

In the two index cases, a novel missense mutation (V205M) was identified in the S3 transmembrane helix of KvLQT1, the pore forming domain of the IKs channel complex. In transfected mouse ltk-cells the V205M mutation suppressed IKs by causing a dramatic depolarizing shift in activation voltage coupled with acceleration of channel deactivation. Twenty-two mutation carriers had a significantly higher mean corrected QT interval than noncarriers (465 +/- 28 milliseconds vs. 434 +/- 26 milliseconds, P < 0.0001); however, 30% of carriers had a corrected QT interval below 440 milliseconds.

CONCLUSION

A novel KCNQ1 mutation in this founder population likely confers increased susceptibility to arrhythmias because of decreased IKs current. Even with a common mutation within a relatively homogenous population, clinical expression remains variable, exemplifying the multifactorial nature of long QT syndrome, and supporting the difficulty of definitive diagnosis without genetic testing. A community participatory approach enabled a comprehensive evaluation of the impact.

Long-term Effects of Implanted Cardioverter-Defibrillators on Health Status, Quality of Life, and Psychological State

Background Living with an implanted cardioverter-defibrillator increases survival, but the effects of the device on health status, quality of life, and psychological state over time are not clear.

Objectives To investigate changes in health status, quality of life, and psychological state associated with implantation of a cardioverter-defibrillator from implantation to 4 years later.

Methods A prospective, longitudinal design was used to measure changes in scores on the Short Form 36 of the Medical Outcomes Study, the Quality of Life Index–Cardiac III, and the Profile of Moods States short form at implantation, 6 months, and 1, 2, 3, and 4 years later.

Results A total of 30 men and 11 women (mean age, 60.4 years) completed all 4 years of follow-up. The physical and mental health composite summary scores of the Short Form 36 changed significantly over time; the mental health score improved (F = 2.95; P = .03), and the physical score worsened (F = 3.69; P = .003). Scores on the Quality of Life Index–Cardiac III did not change significantly. Negative moods were significantly fewer, and the total psychological distress score was significantly lower (F = 10.21; P &lt; .001) during the 4 years of follow-up.

Conclusions Patients had improved mental health and reduced psychological distress by 6 months after implantation. Perception of physical health declined during the 4 years after implantation; the role physical subscore of the Short Form 36 indicated significant improvement in functioning at 6 months and a trend toward reduced functioning at 3 and 4 years after implantation.

Amiodarone—Avoid the danger of Torsade de Pointes

We present two patients who had life-threatening arrhythmias, which are highly likely to be secondary to amiodarone. This class III anti-arrhythmic is commonly prescribed for the acute presentation of supra-ventricular and ventricular arrhythmias. However, occasionally its use can transform arrhythmias from benign to dangerous. These cases highlight the need for careful attention to the indications, cautions and contra-indications of amiodarone as well as the need for vigilance following initiation of anti-arrhythmic therapy.

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.

The Long QT Syndrome

The long QT syndrome (LQTS) is a genetically transmitted cardiac arrhythmia due to ion channel protein abnormalities, which affects the transport of potassium and sodium ions across the cell membrane. Patients with LQTS may present with syncope, seizures or aborted cardiac arrest. LQTS is also an important cause of unexplained sudden cardiac death in the young. The diagnosis of LQTS is generally made on an ECG showing the prolonged QT interval. The establishment of LQTS registry and the discovery of genetic mutations causing LQTS have contributed greatly to the understanding of this condition and have also provided an impetus in understanding of other inherited cardiac arrhythmias. Genotype-phenotype correlation studies have allowed risk stratification of LQTS patients. Life style modification to avoid triggers for malignant cardiac arrhythmias, and the use of beta-blockers, pacemakers and implantable defibrillators, help to treat symptoms and reduce mortality in these patients.

Prevention of Transient Ischemic Attack and Stroke in Older Adults: Implementing Evidence-Based Interventions

By the year 2030, it is estimated there will be more than 70 million adults age 55 and older. Despite the increased risk of transient ischemic attack and stroke after age 55, multiple evidence-based preventive actions can be taken to specifically target manageable health conditions and other modifiable factors that can substantially reduce their likelihood. The purpose of this article is to describe the essential elements in the transient ischemic attack and stroke risk assessment for older adults and the major evidence-based pharmacological and lifestyle stroke-prevention interventions for first ischemic strokes, transient ischemic attacks, and subsequent events.

Multiple downstream proarrhythmic targets for calmodulin kinase II: Moving beyond an ion channel-centric focus

The multifunctional Ca(2+) calmodulin-dependent protein kinase II (CaMKII) has emerged as a pro-arrhythmic signaling molecule. CaMKII can participate in arrhythmia signaling by effects on ion channel proteins, intracellular Ca(2+) uptake and release, regulation of cell death, and by activation of hypertrophic signaling pathways. The pleuripotent nature of CaMKII is reminiscent of another serine-threonine kinase, protein kinase A (PKA), which shares many of the same protein targets and is the downstream kinase most associated with beta-adrenergic receptor stimulation. The ability of CaMKII to localize and coordinate activity of multiple protein targets linked to Ca(2+) signaling set CaMKII apart from other "traditional" arrhythmia drug targets, such as ion channel proteins. This review will discuss some of the biology of CaMKII and focus on work that has been done on molecular, cellular, and whole animal models that together build a case for CaMKII as a pro-arrhythmic signal and as a potential therapeutic target for arrhythmias and structural heart disease.