Utility of electrophysiological studies to predict arrhythmic events

Advances in Cardiac Pacing: Arrhythmia Prediction, Prevention and Control Strategies

Cardiac arrhythmias constitute a tremendous burden on healthcare and are the leading cause of mortality worldwide. An alarming number of people have been reported to manifest sudden cardiac death as the first symptom of cardiac arrhythmias, accounting for about 20% of all deaths annually. Furthermore, patients prone to atrial tachyarrhythmias such as atrial flutter and fibrillation often have associated comorbidities including hypertension, ischemic heart disease, valvular cardiomyopathy and increased risk of stroke. Technological advances in electrical stimulation and sensing modalities have led to the proliferation of medical devices including pacemakers and implantable defibrillators, aiming to restore normal cardiac rhythm. However, given the complex spatiotemporal dynamics and non-linearity of the human heart, predicting the onset of arrhythmias and preventing the transition from steady state to unstable rhythms has been an extremely challenging task. Defibrillatory shocks still remain the primary clinical intervention for lethal ventricular arrhythmias, yet patients with implantable cardioverter defibrillators often suffer from inappropriate shocks due to false positives and reduced quality of life. Here, we aim to present a comprehensive review of the current advances in cardiac arrhythmia prediction, prevention and control strategies. We provide an overview of traditional clinical arrhythmia management methods and describe promising potential pacing techniques for predicting the onset of abnormal rhythms and effectively suppressing cardiac arrhythmias. We also offer a clinical perspective on bridging the gap between basic and clinical science that would aid in the assimilation of promising anti-arrhythmic pacing strategies.

Heart Failure with Preserved Ejection Fraction and Sudden Death: How to Identify High Risk Patients?

Background: Cardiac failure with preserved ejection fraction corresponds to half of the cardiac failure cases, having a similar prognosis to patients with reduced ejection fraction. Cardiac sudden death is responsible to about one quarter of the death on these patients. Despite some trials were intended to identify patients with a higher risk to these outcome, it is not already know: how we should proceed to stratify the risk of sudden death in this patients. Methods: To assess the profile of patients with cardiac sudden death and cardiac failure with preserved ejection fraction, we did a literature review, searching for the newer articles about the theme. Outcome: Several trials were published involving patients with divers characteristics that can help us to identify patients with a higher risk of sudden death. The publication of risk score demonstrated that would be possible to identify patients with a >10% risk of sudden death in 5 years, what would be equivalent to the risk of reduced ejection fraction patients eligible to implantable cardioverter-defibrillator (ICD) therapy. Trials with electrophysiological study and programmed ventricular stimulation showed a good strategy to identify low risk patients for future arrhythmic events. Conclusion: Sudden death must be a target of the therapy in the patients with preserved heart failure. Efforts should be done with the objective to identify higher risk patients and search for the better risk stratification strategy, and after that, the definition of the benefit or not, of the invasive therapy as ICD.

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.

Arrhythmic risk stratification in heart failure: Time for the next step?

BACKGROUND

Primary prevention of sudden cardiac death by means of implantable cardioverter-defibrillators constitutes the holy grail of arrhythmology. However, current risk stratification algorithms lead to suboptimal outcomes, by both allocating ICDs to patients not deriving any meaningful survival benefit and withholding them from those erroneously considered as low-risk for arrhythmic mortality.

METHODS

In the present review article we will attempt to present shortcomings of contemporary guidelines regarding sudden death prevention in ischemic and dilated cardiomyopathy patients and present available data suggesting encouraging results following implementation of multifactorial approaches, by using multiple modalities, both noninvasive and invasive. Invasive electrophysiological testing, namely programmed ventricular stimulation, will be discussed in greater length to highlight both its potential usefulness and currently ongoing multicenter studies aiming to provide evidence necessary to make the next step in sudden death risk stratification.

RESULTS

Promising findings have been reported by multiple study groups regarding novel strategies for both negative selection of low and positive selection of relatively preserved ejection fraction patients as candidates for ICD implantation.

CONCLUSIONS

The era of ejection fraction as the sole risk stratifier for arrhythmic risk in heart failure appears to be drawing to an end, especially if current underway large studies validate previous findings.

Electrophysiologic testing guided risk stratification approach for sudden cardiac death beyond the left ventricular ejection fraction

Sudden cardiac death threats ischaemic and dilated cardiomyopathy patients. Anti- arrhythmic protection may be provided to these patients with implanted cardiac defibrillators (ICD), after an efficient risk stratification approach. The proposed risk stratifier of an impaired left ventricular ejection fraction has limited sensitivity meaning that a significant number of victims will remain undetectable by this risk stratification approach because they have a preserved left ventricular systolic function. Current risk stratification strategies focus on combinations of non invasive methods like T wave alternans, late potentials, heart rate turbulence, deceleration capacity and others, with invasive methods like the electrophysiologic study. In the presence of an electrically impaired substrate with formed post myocardial infarction fibrotic zones, programmed ventricular stimulation provides important prognostic information for the selection of the patients expected to benefit from an ICD implantation, while due to its high negative predictive value, patients at low risk level may also be detected. Clustering evidence from different research groups and electrophysiologic labs support an electrophysiologic testing guided risk stratification approach for sudden cardiac death.