Are nonsustained ventricular tachycardias predictive of major arrhythmias in patients with dilated cardiomyopathy on optimal medical treatment?

Anesthetic Management of Patients with Dilated Cardiomyopathy Undergoing Noncardiac Surgery

Dilated cardiomyopathy (DCM), a primary myocardial disease, is characterized by dilation of the left or both ventricles and systolic dysfunction with or without congestive heart failure. DCM per se is a well-recognized risk factor for sudden cardiac death and poor surgical outcomes following noncardiac surgery. Surgical trauma/stress represents unique challenges for DCM patient management. Unfortunately, there is a big knowledge gap in managing DCM patients undergoing non-cardiac surgery. Therefore, the aim of our review is to provide basic facts and current advances in DCM, as well as a practical guideline to perioperative care providers, for the management of surgical patients with DCM, who are quite rare compared with the general surgical population. This review summarizes recent advances in the medical management of DCM as well as perioperative assessment and management strategies for DCM patients undergoing noncardiac surgery. Optimal surgical outcomes depend on multiple-disciplinary care to minimize perioperative cardiovascular disturbances.

Noninvasive electrocardiographic risk factors for sudden cardiac death in dilated ca rdiomyopathy: is ambulatory electrocardiography still relevant?

Risk stratification for sudden cardiac death in dilated cardiomyopathy is a field of constant debate, and the currently proposed criteria have been widely questioned due to their low positive and negative predictive value. In this study, we conducted a systematic review of the literature utilizing the PubMed and Cochrane library platforms, in order to gain insight about dilated cardiomyopathy and its arrhythmic risk stratification utilizing noninvasive risk markers derived mainly from 24 h electrocardiographic monitoring. The obtained articles were reviewed in order to register the various electrocardiographic noninvasive risk factors used, their prevalence, and their prognostic significance in dilated cardiomyopathy. Premature ventricular complexes, nonsustained ventricular tachycardia, late potentials on Signal averaged electrocardiography, T wave alternans, heart rate variability and deceleration capacity of the heart rate, all have both some positive and negative predictive value to identify patients in higher likelihood for ventricular arrhythmias and sudden cardiac death. Corrected QT, QT dispersion, and turbulence slope-turbulence onset of heart rate have yet to establish a predictive correlation in the literature. Although ambulatory electrocardiographic monitoring is frequently used in clinical practice in DCM patients, no single risk marker can be used for the selection of patients at high-risk for malignant ventricular arrhythmic events and sudden cardiac death who could benefit from the implantation of a defibrillator. More studies are needed in order to establish a risk score or a combination of risk factors with the purpose of selecting high-risk patients for ICD implantation in the context of primary prevention.

Nonsustained Ventricular Tachycardia Is Independently Associated With Sustained Ventricular Arrhythmias in Nonischemic Dilated Cardiomyopathy

BACKGROUND

Spontaneous nonsustained ventricular tachycardia (NSVT) on Holter, VT inducibility during electrophysiology study, and late gadolinium enhancement (LGE) on cardiac magnetic resonance (CMR) have been associated with sustained ventricular arrhythmias (SVAs) in nonischemic dilated cardiomyopathy (DCM). This study aimed to analyze whether these parameters carry independent prognostic value for spontaneous SVA in DCM.

METHODS

Between 2011 and 2018, patients with the DCM clinical spectrum and documented SVA, suspected SVA, or considered to be at intermediate or high risk for SVA were enrolled in the prospective Leiden Nonischemic Cardiomyopathy Study. Patients underwent a comprehensive evaluation including 24-hour Holter, LGE-CMR, and electrophysiology study. Holters were assessed for the presence of NSVT (≥3 beats; rate, ≥120 bpm; lasting <30 s) and NSVT characteristics (coupling interval, duration, cycle length, morphology, regularity). Patients were followed at 6 to 12 monthly intervals.

RESULTS

Of all 115 patients (age, 59±12 years; 77% men; left ventricular ejection fraction, 33±13%; history of SVA, 36%; LGE in 63%; median LGE mass, 13 g; interquartile range, 8-23 g), 62 (54%) had NSVT on Holter, and sustained monomorphic VT was inducible in 34 of 114 patients (30%). NSVT was not associated with LGE on CMR or VT inducibility during electrophysiology study nor were its features (all P>0.05). During 4.0±1.8 years of follow-up, SVA occurred in 39 patients (34%). NSVT (HR, 4.47 [95% CI, 1.87-10.72]; P=0.001) and VT inducibility (HR, 3.08 [95% CI, 1.08-8.81]; P=0.036) were independently associated with SVA during follow-up. A bivariable model including only noninvasively acquired parameters also allowed identification of a high-risk subgroup (ie, those with both NSVT and LGE on CMR). The findings remained similar when only patients without prior SVA were included.

CONCLUSIONS

In patients with DCM, NSVT on Holter and VT inducibility during electrophysiology study predict SVA during follow-up independent of LGE on CMR. NSVTs may serve as an initiator, and sustained VT inducibility indicates the presence of the substrate for SVA in DCM. Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT01940081.

The Arrhythmic Phenotype in Cardiomyopathy

In the wide phenotypic spectrum of cardiomyopathies, sudden cardiac death (SCD) has always been the most visible and devastating disease complication. The introduction of implantable cardioverter-defibrillators for SCD prevention by the late 1980s has moved the question from how to whom we should protect from SCD, leaving clinicians with a measure of uncertainty regarding the most reliable option to guide identification of the highest-risk patients. In this review, we will go through all the available evidence in the field of arrhythmic expression and arrhythmic risk stratification in the different phenotypes of cardiomyopathies to provide practical suggestions in daily clinical management.

Non-invasive markers for sudden cardiac death risk stratification in dilated cardiomyopathy

Dilated cardiomyopathy (DCM) is a common yet challenging cardiac disease. Great strides have been made in improving DCM prognosis due to heart failure but sudden cardiac death (SCD) due to ventricular arrhythmias remains significant and challenging to predict. High-risk patients can be effectively managed with implantable cardioverter defibrillators (ICDs) but because identification of what is high risk is very limited, many patients unnecessarily experience the morbidity associated with an ICD implant and many others are not identified and have preventable mortality. Current guidelines recommend use of left ventricular ejection fraction and New York Heart Association class as the main markers of risk stratification to identify patients who would be at higher risk of SCD. However, when analysing the data from the trials that these recommendations are based on, the number of patients in whom an ICD delivers appropriate therapy is modest. In order to improve the effectiveness of therapy with an ICD, the patients who are most likely to benefit need to be identified. This review article presents the evidence behind current guideline-directed SCD risk markers and then explores new potential imaging, electrophysiological and genetic risk markers for SCD in DCM.

Contemporary etiology and prognosis of dilated non-ischemic cardiomyopathy

INTRODUCTION

Non-ischemic dilated cardiomyopathy (NI-DCM) represents a specific etiology of systolic heart failure that usually affect young individuals with a genetic background in up to 40% of cases. Behind the term NI-DCM there is a spectrum of different diseases, and an accurate etiological classification appears pivotal for the clinical management and prognostic stratification of these patients.

EVIDENCE ACQUISITION

In the last years the prognosis of NI-DCM patients dramatically improved thanks to the progresses in medical treatment/ device therapy and earlier diagnosis especially in familial context. In this review we summarize the actual state of art in the management of these patients.

EVIDENCE SYNTHESIS

In the era of precision medicine, a lot of progresses have been made to expand our knowledge on the management of NI-DCM patients. A complex interaction between genotype and external triggers is the main determinant of the clinical phenotype in NI-DCM, and a lot of efforts must be done by clinicians to systematically rule out all the possible causes involved in the pathogenesis. Progresses in cardiac imaging and familial screening led us to detect subtle abnormalities in the initial phase of the disease and also helped us to furtherly stratify the prognosis and arrhythmic risk of these patients. It is plausible that a more precise etiological classification will be needed in the near future.

CONCLUSIONS

NI-DCM contains a spectrum of different diseases. Proper etiological classification, early diagnosis and strict follow-up are essential to tailor care of these patients.

CMR-Based Risk Stratification of Sudden Cardiac Death and Use of Implantable Cardioverter-Defibrillator in Non-Ischemic Cardiomyopathy

Non-ischemic cardiomyopathy (NICM) is one of the most important entities for arrhythmias and sudden cardiac death (SCD). Previous studies suggest a lower benefit of implantable cardioverter–defibrillator (ICD) therapy in patients with NICM as compared to ischemic cardiomyopathy (ICM). Nevertheless, current guidelines do not differentiate between the two subgroups in recommending ICD implantation. Hence, risk stratification is required to determine the subgroup of patients with NICM who will likely benefit from ICD therapy. Various predictors have been proposed, among others genetic mutations, left-ventricular ejection fraction (LVEF), left-ventricular end-diastolic volume (LVEDD), and T-wave alternans (TWA). In addition to these parameters, cardiovascular magnetic resonance imaging (CMR) has the potential to further improve risk stratification. CMR allows the comprehensive analysis of cardiac function and myocardial tissue composition. A range of CMR parameters have been associated with SCD. Applicable examples include late gadolinium enhancement (LGE), T1 relaxation times, and myocardial strain. This review evaluates the epidemiological aspects of SCD in NICM, the role of CMR for risk stratification, and resulting indications for ICD implantation.

Clinical Predictors of Occurrence of Ventricular Tachyarrhythmias in Patients with Reduced Left Ventricle Ejection Fraction. Results of Single-Center Prospective Study

Aim      To evaluate the diagnostic significance of clinical and demographic parameters for predicting a 2-year probability of ventricular tachyarrhythmias (VT) in patients with chronic heart failure and reduced left ventricular ejection fraction (CHFrLVEF).Material and methods  This single-center, prospective cohort study included 175 patients with CHFrLVEF who were implanted with a cardioverter defibrillator (CD). The endpoint was a CD-detected episode of VT. Patients were followed up for 2 years with visits at 3, 12, and 24 months after CD implantation.Results The primary endpoint was observed in 43 (24.4 %) patients at an average of 20.9 months (95 % confidence interval (CI), 20-21.9). The 2-year risk of fatal ventricular arrhythmias increased with detection of unstable VT (one-factor analysis, odds ratio (OR), 4.2; 95 % CI, 1.1-16.5; р=0.041; multifactor analysis, OR, 6.3; 95 % CI, 1.5-26.3; р=0.012) and with ischemic CHFrLVEF origin (one-factor analysis, OR, 2.2; 95 % CI, 1.1-4.5; p=0.021; multifactor analysis, OR, 2.5; 95 % CI, 1.2-5.1; р=0.018). In the presence of any type of atrial fibrillation (AF) in patients with non-ischemic CHFrLVEF, the probability of VT increased threefold (one-factor analysis, OR, 2.97; 95 % CI, 1.02-8.8; р=0.047; multifactor analysis, OR, 3.5; 95 % CI, 1.1-10.9; р=0.032).Conclusion      The presence of ischemic heart disease and unstable VT paroxysms can be included in the number of important clinical predictors of VT in patients with CHFrLVEF. In patients with non-ischemic CHF, the presence of AF is associated with a high risk of VT.

Rapid-rate nonsustained ventricular tachycardias in high-risk dilated cardiomyopathy patients

AIMS

Nonsustained ventricular tachycardia (NSVT) occurs frequently in patients with dilated cardiomyopathy (DCM), especially in high-risk patients. The role of rapid-rate NSVT (RR-NSVT) documented by an implantable cardioverter-defibrillator (ICD) in DCM patients has not been fully explored. This study aimed to determine the relationship between RR-NSVT and the occurrence of ventricular tachyarrhythmias (VTAs) in DCM patients with ICD.

METHODS

From December 2000 to December 2017, 136 DCM patients received ICD or cardiac resynchronization therapy defibrillator (CRT-D) implantation for primary or secondary prevention of VTAs. Based on the occurrence of documented RR-NSVT, patients were classified into RR-NSVT (-) or RR-NSVT (+) groups.

RESULT

During the median follow-up of 4.5 years, 50.0% (68/136) patients experienced ≥1 episode, and 25.0% (34/136) patients experienced ≥3 episodes of RR-NSVT. Event-free survival for VTAs was significantly higher in the RR-NSVT (-) group, whereas those for heart failure admission and cardiovascular mortality were comparable between groups. In the multivariate Cox regression analysis, any RR-NSVT showed a positive association with the occurrence of VTAs (hazard ratio: 5.087; 95% confidence interval: 2.374-10.900; P < .001). In RR-NSVT (+) patients, a cluster (≥3 times/6 months) and frequent pattern (≥3 runs/day) of RR-NSVT were observed in 42.6% (29/68) and 30.9% (21/68) patients, respectively, who showed further increased incidence of VTAs.

CONCLUSION

In DCM patients with ICD/CRT-D, 50.0% patients experienced at least one episode of RR-NSVT. RR-NSVT documentation showed a positive association with subsequent occurrence of VTAs, suggesting the importance of constructive arrhythmia management for patients with RR-NSVT.

Sudden Cardiac Death Prediction in Non-ischemic Dilated Cardiomyopathy: a Multiparametric and Dynamic Approach

PURPOSE OF REVIEW

Sudden cardiac death is recognised as a devastating consequence of non-ischaemic dilated cardiomyopathy. Although implantable cardiac defibrillators offer protection against some forms of sudden death, the identification of patients in this population most likely to benefit from this therapy remains challenging and controversial. In this review, we evaluate current guidelines and explore established and novel predictors of sudden cardiac death in patients with non-ischaemic dilated cardiomyopathy.

RECENT FINDINGS

Current international guidelines for primary prevention implantable defibrillator therapy do not result in improved longevity for many patients with non-ischemic cardiomyopathy and severe left ventricular dysfunction. More precise methods for identifying higher-risk patients that derive true prognostic benefit from this therapy are required. Dynamic and multi-parametric characterization of myocardial, electrical, serological and genetic substrate offers novel strategies for predicting major arrhythmic risk. Balancing the risk of non-sudden death offers an opportunity to personalize therapy and avoid unnecessary device implantation for those less likely to derive benefit.

Risk Stratification for Sudden Cardiac Death in Non-Ischaemic Dilated Cardiomyopathy

Purpose of Review

Non-ischaemic dilated cardiomyopathy (DCM) occurs in 1 in 2500 individuals in the general population and is associated with considerable morbidity and mortality. Studies involving large numbers of unselected DCM patients have led to consensus guidelines recommending implantable cardioverter-defibrillator (ICD) implantation for protection against sudden cardiac death (SCD) in those with LVEF ≤35%. The purpose of this article is to review the literature for other potential markers including serological, electrocardiographic, echocardiographic, cardiac magnetic resonance, ambulatory ECG and genetic data, to highlight other potential markers that may optimise risk stratification for SCD in this cohort and thereby allow a more personalized approach to ICD-implantation.

Recent Findings

Recent studies including the Danish study to assess the efficacy of ICDs in patients with non-ischemic systolic heart failure on mortality (DANISH) trial have questioned the benefits of ICD implantation in this group of patients with no changes in all-cause mortality. Recent pooled cohorts of patients with genetic DCM and in particular in those with Lamin A/C (LMNA) mutations have identified patients at increased risk of SCD and allowed the creation of algorithms to prognosticate SCD risk in mutation carriers. Furthermore, genetic testing has identified other DCM-causing genes including filamin C (FLNC) and RBM20 which may be associated with higher rates of ventricular arrhythmia.

Summary

To date, risk-stratification for SCD has been hampered by the utilisation of heterogenous subsets of idiopathic DCM patients and by use of static risk models where predictions are based on a single time point with a lack of consideration of disease progression. The current focus of personalised risk-stratification for SCD is shifting towards better characterisation of underlying DCM aetiology and the development of multi-parametric risk-stratification models that incorporate time-dependent disease characteristics and novel biomarkers.

Global Longitudinal Strain as a Predictor of First and Subsequent Arrhythmic Events in Remotely Monitored ICD Patients With Structural Heart Disease

OBJECTIVES

This study sought to assess speckle-tracking-derived parameters as predictors of first and subsequent ventricular events in patients with structural heart disease and implantable cardioverter-defibrillators (ICD).

BACKGROUND

Left ventricular ejection fraction (LVEF), the current primary parameter of risk stratification for ventricular arrhythmias (VAs) in structural heart diseases is burdened by many limitations.

METHODS

In this retrospective, observational study, all consecutive patients with structural heart disease were admitted for ICD implantation. Patients not followed by a home-monitoring system were excluded. Two-dimensional (2D) speckle-tracking analysis was used to derive global longitudinal strain (GLS), mechanical dispersion (MD), and delta contraction duration (DCD) of all patients at enrollment. Home monitoring was checked weekly to detect all VAs and ICD therapies. A recurrent event statistical approach (Prentice, Williams, and Peterson model) was applied to evaluate subsequent events after the first ones.

RESULTS

A total of 203 patients were consecutively enrolled and followed for a median of 2.2 years. Kaplan-Meier curves showed an increased risk of antitachycardia pacing or shock (log-rank p = 0.003) and VAs (log-rank p = 0.001) associated with lower quartiles of GLS. An impaired GLS was independently associated with an increased risk for the first ICD therapy (hazard ratio [HR]: 1.94; 95% confidence interval [CI]: 1.30 to 2.91; p = 0.001) and (HR: 1.42; 95% CI: 1.01 to 1.98; p = 0.04) for the first VA. GLS impairment was not significantly associated with an increased risk of recurrent ICD therapies or VAs. LVEF, MD, and DCD were not associated with an increased risk of first, second, and third ICD therapies or VA.

CONCLUSIONS

Impaired GLS is associated with an increased risk of VAs and appropriate ICD therapies in a consecutive "real-world," unselected population of remotely monitored patients with structural heart disease, although it does not seem reliable in predicting further arrhythmic events after the first one. MD and DCD do not predict first or subsequent arrhythmic events in ICD patients with structural heart disease.

Risk Stratification of Sudden Cardiac Death in Patients with Heart Failure: An update

Heart failure (HF) is a complex clinical syndrome in which structural/functional myocardial abnormalities result in symptoms and signs of hypoperfusion and/or pulmonary or systemic congestion at rest or during exercise. More than 80% of deaths in patients with HF recognize a cardiovascular cause, with most being either sudden cardiac death (SCD) or death caused by progressive pump failure. Risk stratification of SCD in patients with HF and preserved (HFpEF) or reduced ejection fraction (HFrEF) represents a clinical challenge. This review will give an update of current strategies for SCD risk stratification in both HFrEF and HFpEF.

Recommendations for the use of electrophysiological study: Update 2018

The field of cardiac electrophysiology has greatly developed during the past decades. Consequently, the use of electrophysiological studies (EPSs) in clinical practice has also significantly augmented, with a progressively increasing number of certified electrophysiology centers and specialists. Since Zipes et al published the Guidelines for Clinical Intracardiac Electrophysiology and Catheter Ablation Procedures in 1995, no official document summarizing current EPS indications has been published. The current paper focuses on summarizing all relevant data of the role of EPS in patients with different types of cardiac pathologies and provides up-to-date recommendations on this topic. For this purpose, the PubMed database was screened for relevant articles in English up to December 2018 and ESC and ACC/AHA Clinical Practice Guidelines, and EHRA/HRS/APHRS position statements related to the current topic were analyzed. Current recommendations for the use of EPS in clinical practice are discussed and presented in 17 distinct cardiac pathologies. A short rationale, evidence, and indications are provided for each cardiac disease/group of diseases. In conclusion, because of its capability to establish a diagnosis in patients with a variety of cardiac pathologies, the EPS remains a useful tool in the evaluation of patients with cardiac arrhythmias and conduction disorders and is capable of establishing indications for cardiac device implantation and guide catheter ablation procedures.

Prognostic significance of nonsustained ventricular tachycardia in patients receiving cardiac resynchronization therapy for primary prevention: Analysis of the Japan cardiac device treatment registry database

Background

Whether nonsustained ventricular tachycardia (NSVT) is a marker of increased risk of sustained ventricular tachyarrhythmias (VTAs) remains to be established in patients receiving cardiac resynchronization therapy with a defibrillator (CRT‐D) for primary prevention.

Methods

Among the follow‐up data of the Japan cardiac device treatment registry (JCDTR) with an implantation date between January 2011 and August 2015, information regarding a history of NSVT before the CRT‐D implantation for primary prevention had been registered in 269 patients. Outcomes were compared between two groups with and without NSVT: NSVT group (n = 179) and No NSVT group (n = 90).

Results

There was no significant difference with regard to age, gender, and NYHA class between the two groups. Left ventricular ejection fraction (LVEF) was 25.6% in the NSVT group and 28.0% in the No NSVT group (P = .046). The rate of appropriate therapy at 24 months was 26.0% and 18.4% in the NSVT and No NSVT groups (P = .22), respectively. Survival free from heart failure death was reduced in the NSVT group, as compared with the No NSVT group, with the rate of 90.2% vs 97.2% at 24 months (P = .030). A multivariate analysis identified a history of NSVT, anemia, and no use of angiotensin‐converting enzyme inhibitor (ACEI) or angiotensin‐receptor blocker (ARB) as predictors of heart failure death.

Conclusions

NSVT appears to be a surrogate marker of severe heart failure rather than a substrate for subsequent sustained VTAs in patients with CRT‐D for primary prevention.

Arrhythmogenic Phenotype in Dilated Cardiomyopathy: Natural History and Predictors of Life-Threatening Arrhythmias

BACKGROUND

Patients with dilated cardiomyopathy (DCM) may present with ventricular arrhythmias early in the disease course, unrelated to the severity of left ventricular dysfunction. These patients may be classified as having an arrhythmogenic DCM (AR-DCM). We investigated the phenotype and natural history of patients with AR-DCM.

METHODS AND RESULTS

Two hundred eighty-five patients with a recent diagnosis of DCM (median duration of the disease 1 month, range 0 to 7 months) and who had Holter monitoring at baseline were comprehensively evaluated and followed for 107 months (range 29 to 170 months). AR-DCM was defined by the presence of ≥1 of the following: unexplained syncope, rapid nonsustained ventricular tachycardia (≥5 beats, ≥150 bpm), ≥1000 premature ventricular contractions/24 hours, and ≥50 ventricular couplets/24 hours, in the absence of overt heart failure. The primary end points were sudden cardiac death (SCD), sustained ventricular tachycardia (SVT), or ventricular fibrillation (VF). The secondary end points were death from congestive heart failure or heart transplantation. Of the 285 patients, 109 (38.2%) met criteria for AR-DCM phenotype. AR-DCM subjects had a higher incidence of SCD/SVT/VF compared with non-AR-DCM patients (30.3% vs 17.6%, P=0.022), with no difference in the secondary end points. A family history of SCD/SVT/VF and the AR-DCM phenotype were statistically significant and cumulative predictors of SCD/SVT/VF.

CONCLUSIONS

One-third of DCM patients may have an arrhythmogenic phenotype associated with increased risk of arrhythmias during follow-up. A family history of ventricular arrhythmias in DCM predicts a poor prognosis and increased risk of SCD.

Diagnosis, prevalence, and screening of familial dilated cardiomyopathy

INTRODUCTION

Dilated cardiomyopathy (DCM) is the most common cardiomyopathy and occurs often in families. As an inherited disease, understanding the significance of diagnostic procedures and genetic screening within families is of utmost importance.

AREAS COVERED

Genetic studies have shown that in 30-40% of familial DCM (FDC) cases a causative genetic mutation can be identified. Successful genetic analysis is highly dependent on close examination of patient and family history, and clinical guidelines exist recommending genetic testing to aid in the evaluation of family members at risk of developing FDC. Clinical genetic testing offers a resource for families to identify the etiology of their disease, and in some cases may provide clinical prognostic insight.

EXPERT OPINION

As an inherited disease, future FCD studies will focus on elucidating the remaining 60-70% of genetic causes in inherited cases and the pathogenic mechanisms leading to the phenotype. Specifically, a focus on regulatory regions, copy number variation, genetic and environmental modifiers and functional confirmatory investigations will be essential.

[Risk stratification of sudden cardiac death in dilated cardiomyopathy. Programmed ventricular stimulation]

There is a strong correlation between clinical presentation and results of the electrophysiological study (EPS) in patients with dilated cardiomyopathy. Patients with spontaneous ventricular tachycardia (VT) or syncope often have inducible VT in contrast to patients who have no history of arrhythmias or syncope. Therefore, the EPS is rather not useful for risk stratification but for planning of an adjuvant antiarrhythmic or ablation therapy. This is also true for patients with frequent ventricular extrasystole or nonsustained VT in whom VT may aggravate heart failure. An EP study may still be useful to differentiate between syncope of bradycardic or tachycardic origin.

Molecular imaging to predict ventricular arrhythmia in heart failure

Ventricular tachycardia (VT) is a major cause of sudden cardiac death (SCD) in patients with heart failure (HF). Left ventricular ejection fraction (LVEF) and heart failure class according to the New York Heart association (NYHA) are in most common use to identify patients that may benefit from implantable cardioverter defibrillator (ICD) therapy. But during 3 years of follow up only 35% of patients receive appropriate ICD action. Therefore, there is a continued need for refinement of selection criteria for ICD implantation. In this regard, molecular imaging of the autonomic nervous system, which plays a central role in HF progression and cardiac electro-mechanical regulation, can make a substantial contribution. This article reviews the currently available literature concerning the value of molecular neuronal cardiac imaging for prediction of ventricular arrhythmias in HF patients.

The usual suspects in sudden cardiac death of the young: a focus on inherited arrhythmogenic diseases

Up to 14,500 young individuals die suddenly every year in Europe of cardiac pathologies. The majority of these tragic events are related to a group of genetic defects that predispose the development of malignant arrhythmias (inherited arrhythmogenic diseases [IADs]). IADs include both cardiomyopathies (hypertrophic cardiomyopathy, arrhythmogenic right ventricular cardiomyopathy, dilated cardiomyopathy) and channelopathies (long QT syndrome, short QT syndrome, Brugada syndrome and catecholaminergic polymorphic ventricular tachycardia). Every time an IAD is identified in a patient, other individuals in his/her family may be at risk of cardiac events. However; if a timely diagnosis is made, simple preventative measures may be applied. Genetic studies play a pivotal role in the diagnosis of IADs and may help in the management of patients and their relatives.

Risk stratification of ventricular arrhythmias in patients with systolic heart failure

PURPOSE OF REVIEW

Sudden cardiac death (SCD) accounts for an estimated 310 000 deaths in the United States each year. Implantable cardioverter defibrillator (ICD) implantation has revolutionized SCD prevention in heart failure patients, but only a minority of patients with ICDs receive appropriate therapy for ventricular arrhythmias. At present, the selection of patients for ICD is based largely on left ventricular ejection fraction and heart failure, but further risk stratification is still needed to determine which patients will derive the greatest benefit.

RECENT FINDINGS

Multicenter studies have failed to confirm the utility of microvolt T-wave alternans to predict ventricular arrhythmias in patients with ICDs. Additional risk stratification tools including resting ECG characteristics, nonsustained ventricular tachycardia, tests of autonomic function, and cardiac MRI demonstrate predictive value but have limited clinical applicability at present.

SUMMARY

Depressed ejection fraction with symptomatic heart failure remains the most powerful predictor of SCD and is the primary method currently used in patient care decisions. Progress continues in evaluation of additional risk factors and risk stratification tools, but no one test or combination of tests is definitive for prediction of arrhythmic events.

Nonsustained ventricular tachycardia

Nonsustained ventricular tachycardia (NSVT) has been recorded in a wide range of conditions, from apparently healthy individuals to patients with significant heart disease. In the absence of heart disease, the prognostic significance of NSVT is debatable. When detected during exercise, and especially at recovery, NSVT indicates increased cardiovascular mortality within the next decades. In trained athletes, NSVT is considered benign when suppressed by exercise. In patients with non-ST-segment elevation acute coronary syndrome, NSVT occurring beyond 48 h after admission indicates an increased risk of cardiac and sudden death, especially when associated with myocardial ischemia. In acute myocardial infarction, in-hospital NSVT has an adverse prognostic significance when detected beyond the first 13 to 24 h. In patients with prior myocardial infarction treated with reperfusion and beta-blockers, NSVT is not an independent predictor of long-term mortality when other covariates such as left ventricular ejection fraction are taken into account. In patients with hypertrophic cardiomyopathy, and most probably genetic channelopathies, NSVT carries prognostic significance, whereas its independent prognostic ability in ischemic heart failure and dilated cardiomyopathy has not been established. The management of patients with NSVT is aimed at treating the underlying heart disease.

How can optimization of medical treatment avoid unnecessary implantable cardioverter-defibrillator implantations in patients with idiopathic dilated cardiomyopathy presenting with "SCD-HeFT criteria?"

To assess the proportion and long-term outcomes of patients with idiopathic dilated cardiomyopathy and potential indications for implantable cardioverter-defibrillator before and after optimization of medical treatment, 503 consecutive patients with idiopathic dilated cardiomyopathy were evaluated from 1988 to 2006. A total of 245 patients (49%) satisfied the "Sudden Cardiac Death in Heart Failure Trial (SCD-HeFT) criteria," defined as a left ventricular ejection fraction of ≤0.35 and New York Heart Association (NYHA) class II-III on registration. Among these, 162 (group A) were re-evaluated 5.4 ± 2 months later with concurrent β-blockers and angiotensin-converting enzyme inhibitor use. Of the 162 patients, 50 (31%) still had "SCD-HeFT criteria" (group A1), 109 (67%) had an improved left ventricular ejection fraction and/or New York Heart Association class (group A2), and 3 (2%) were in NYHA class IV. Of the 227 patients without baseline "SCD-HeFT criteria" (left ventricular ejection fraction >0.35 or NYHA class I), 125 were evaluated after 5.5 ± 2 months. Of these 227 patients, 13 (10%) developed "SCD-HeFT criteria" (group B1), 111 (89%) remained without "SCD-HeFT criteria" (group B2), and 1 (1%) had worsened to NYHA class IV. The 10-year mortality/heart transplantation and sudden death/sustained ventricular arrhythmia rate was 57% and 37% in group A1, 23% and 20% in group A2 (p <0.001 for mortality/heart transplantation and p = 0.014 for sudden death/sustained ventricular arrhythmia vs group A1), 45% and 41% in group B1 (p = NS vs group A1), 16% and 14% in group B2 (p = NS vs group A2), respectively. In conclusion, two thirds of patients with idiopathic dilated cardiomyopathy and "SCD-HeFT criteria" at presentation did not maintain implantable cardioverter-defibrillator indications 3 to 9 months later with optimal medical therapy. Their long-term outcome was excellent, similar to that observed for patients who had never met the "SCD-HeFT criteria."

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.

Sudden cardiac death risk stratification in patients with heart failure

The multiplicity of mechanisms contributing to arrhythmogenesis in patients with heart failure carries obvious implications for risk stratification. If patients having the propensity to develop arrhythmias by these different mechanisms are to be identified, tests must be devised that reveal the substrates or other factors that relate to each mechanism. In the absence of this, efforts to risk stratify patients are likely to be neither cost-effective nor accurate. This article reviews the current knowledge base of risk stratification for sudden death in patients with heart failure, while acknowledging several limitations in the studies examined.