Recurrent sustained ventricular tachycardia 3. Role of the electrophysiologic study in selection of antiarrhythmic regimens

Programmed Ventricular Stimulation: Risk Stratification and Guiding Antiarrhythmic Therapies

Electrophysiologic testing with programmed ventricular stimulation (PVS) has been utilized to induce ventricular tachycardia (VT), thereby improving risk stratification for patients with ischemic and nonischemic cardiomyopathies and determining the effectiveness of antiarrhythmic therapies, especially catheter ablation. A variety of procedural aspects can be modified during PVS in order to alter the sensitivity and specificity of the test including the addition of multiple baseline pacing cycle lengths, extrastimuli, and pacing locations. The definition of a positive result is also critically important, which has varied from exclusively sustained monomorphic VT (>30 seconds) to any ventricular arrhythmia regardless of morphology. In this review, we discuss the history of PVS and evaluate its role in sudden cardiac death risk stratification in a variety of patient populations. We propose an approach to future investigations that will capitalize on the unique ability to vary the sensitivity and specificity of this test. We then discuss the application of PVS during and following catheter ablation. The strategies that have been utilized to improve the efficacy of intraprocedural PVS are highlighted during a discussion of the limitations of this probabilistic strategy. The role of noninvasive programmed stimulation is also reviewed in predicting recurrent VT and informing management decisions including repeat ablations, modifications in antiarrhythmic drugs, and implantable cardioverter-defibrillator programming. Based on the available evidence and guidelines, we propose an approach to future investigations that will allow clinicians to optimize the use of PVS for risk stratification and assessment of therapeutic efficacy.

Pharmacologic Management for Ventricular Arrhythmias: Overview of Anti-Arrhythmic Drugs

Ventricular arrhythmias (Vas) are a life-threatening condition and preventable cause of sudden cardiac death (SCD). With the increased utilization of implantable cardiac defibrillators (ICD), the focus of VA management has shifted toward reduction of morbidity from VAs and ICD therapies. Anti-arrhythmic drugs (AADs) can be an important adjunct therapy in the treatment of recurrent VAs. In the treatment of VAs secondary to structural heart disease, amiodarone remains the most well studied and current guideline-directed pharmacologic therapy. Beta blockers also serve as an important adjunct and are a largely underutilized medication with strong evidentiary support. In patients with defined syndromes in structurally normal hearts, AADs can offer tailored therapies in prevention of SCD and improvement in quality of life. Further clinical trials are warranted to investigate the role of newer therapeutic options and for the direct comparison of established AADs.

2019 HRS/EHRA/APHRS/LAHRS expert consensus statement on catheter ablation of ventricular arrhythmias

Ventricular arrhythmias are an important cause of morbidity and mortality and come in a variety of forms, from single premature ventricular complexes to sustained ventricular tachycardia and fibrillation. Rapid developments have taken place over the past decade in our understanding of these arrhythmias and in our ability to diagnose and treat them. The field of catheter ablation has progressed with the development of new methods and tools, and with the publication of large clinical trials. Therefore, global cardiac electrophysiology professional societies undertook to outline recommendations and best practices for these procedures in a document that will update and replace the 2009 EHRA/HRS Expert Consensus on Catheter Ablation of Ventricular Arrhythmias. An expert writing group, after reviewing and discussing the literature, including a systematic review and meta-analysis published in conjunction with this document, and drawing on their own experience, drafted and voted on recommendations and summarized current knowledge and practice in the field. Each recommendation is presented in knowledge byte format and is accompanied by supportive text and references. Further sections provide a practical synopsis of the various techniques and of the specific ventricular arrhythmia sites and substrates encountered in the electrophysiology lab. The purpose of this document is to help electrophysiologists around the world to appropriately select patients for catheter ablation, to perform procedures in a safe and efficacious manner, and to provide follow-up and adjunctive care in order to obtain the best possible outcomes for patients with ventricular arrhythmias.

2019 HRS/EHRA/APHRS/LAHRS expert consensus statement on catheter ablation of ventricular arrhythmias

Ventricular arrhythmias are an important cause of morbidity and mortality and come in a variety of forms, from single premature ventricular complexes to sustained ventricular tachycardia and fibrillation. Rapid developments have taken place over the past decade in our understanding of these arrhythmias and in our ability to diagnose and treat them. The field of catheter ablation has progressed with the development of new methods and tools, and with the publication of large clinical trials. Therefore, global cardiac electrophysiology professional societies undertook to outline recommendations and best practices for these procedures in a document that will update and replace the 2009 EHRA/HRS Expert Consensus on Catheter Ablation of Ventricular Arrhythmias. An expert writing group, after reviewing and discussing the literature, including a systematic review and meta-analysis published in conjunction with this document, and drawing on their own experience, drafted and voted on recommendations and summarized current knowledge and practice in the field. Each recommendation is presented in knowledge byte format and is accompanied by supportive text and references. Further sections provide a practical synopsis of the various techniques and of the specific ventricular arrhythmia sites and substrates encountered in the electrophysiology lab. The purpose of this document is to help electrophysiologists around the world to appropriately select patients for catheter ablation, to perform procedures in a safe and efficacious manner, and to provide follow-up and adjunctive care in order to obtain the best possible outcomes for patients with ventricular arrhythmias.

2019 HRS/EHRA/APHRS/LAHRS expert consensus statement on catheter ablation of ventricular arrhythmias

Ventricular arrhythmias are an important cause of morbidity and mortality and come in a variety of forms, from single premature ventricular complexes to sustained ventricular tachycardia and fibrillation. Rapid developments have taken place over the past decade in our understanding of these arrhythmias and in our ability to diagnose and treat them. The field of catheter ablation has progressed with the development of new methods and tools, and with the publication of large clinical trials. Therefore, global cardiac electrophysiology professional societies undertook to outline recommendations and best practices for these procedures in a document that will update and replace the 2009 EHRA/HRS Expert Consensus on Catheter Ablation of Ventricular Arrhythmias. An expert writing group, after reviewing and discussing the literature, including a systematic review and meta-analysis published in conjunction with this document, and drawing on their own experience, drafted and voted on recommendations and summarized current knowledge and practice in the field. Each recommendation is presented in knowledge byte format and is accompanied by supportive text and references. Further sections provide a practical synopsis of the various techniques and of the specific ventricular arrhythmia sites and substrates encountered in the electrophysiology lab. The purpose of this document is to help electrophysiologists around the world to appropriately select patients for catheter ablation, to perform procedures in a safe and efficacious manner, and to provide follow-up and adjunctive care in order to obtain the best possible outcomes for patients with ventricular arrhythmias.

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.

Mark E Josephson: Clinical Investigator

Mark E Josephson entered the world of clinical cardiac electrophysiology (EP) almost at its inception (1972); with so much to learn and so many directions one could take, he dived into the field with unbridled enthusiasm and an uncommon - perhaps almost unique - aptitude for asking questions and finding ways to answer them. Few aspects of EP escaped his indelible influence. In this short paper, I will attempt to touch on some of the high points of his astounding career as a clinical investigator.

Analytic Reviews: Electrophysiologic Testing in the Intensive Care Unit

The role of electrophysiologic concepts and procedures in managing patients with potentially life-threatening ar rhythmias in the intensive care unit is discussed. These patients may be survivors of sudden cardiac arrest or myocardial infarction or may be admitted for syncope or sustained or nonsustained ventricular tachycardia. The value of electrophysiologic testing is discussed in terms of the distinction between wide QRS complex tachycardias that are supraventricular or ventricular in origin and those in which preexcitation syndromes may be important. Drug-induced ventricular arrhythmias are discussed, with specific emphasis on torsades de pointes. Finally, the use of His bundle recordings in pa tients with atrioventricular conduction disturbances is discussed. The methodology of electrophysiologic test ing, including stimulation protocols and interpretation of results, is described.

Non-invasive programmed stimulation to identify high-risk patients with implanted cardioverter defibrillator (the NIPS-ICD study): study protocol for a randomized controlled trial

Background

The use of an implantable cardioverter defibrillator (ICD) is a widely used and effective therapy, which reduces the risk of cardiac death in many cardiac diseases, both implanted for secondary and primary prevention. However, recurrent arrhythmias and ICD discharges have adverse prognostic significance. Additional parameters that would identify patients who are at increased risk of arrhythmias and appropriate ICD interventions would be of clinical value. Modern ICDs are relatively complex devices with a number of functions, including the possibility to perform noninvasive programmed stimulation (NIPS) with an implanted electrode located in the right ventricle.

Methods/Design

The aim of the study is to evaluate the usefulness of NIPS in determining the likelihood of life-threatening arrhythmic events in patients with ICD. The study will include 150 consecutive patients with an ICD implanted both for primary and secondary prevention, regardless of etiology, who are followed in the outpatient clinic of our center and do not meet the exclusion criteria. A 12-step St. George’s Hospital NIPS protocol using ICD will be performed. The endpoint is to induce sustained ventricular arrhythmia (VT lasting more than 30 seconds or hemodynamically unstable VT/VF) or the end of the protocol. In case of serious and/or hemodynamically unstable heart rhythm disorders resistant to treatment with a low-energy antiarrhythmic pacing (ATP), the patient receives a short-term intravenous general anesthesia, and internal or external defibrillation is performed. Outpatient follow-up will be conducted during the pre-scheduled ICD control visits. An analysis of records of a registered memory device will be collected, a patient will be interviewed, and physical examination will be carried out. The follow-ups will be held every 3 months for 1 year. The primary endpoint of the follow-up will be appropriate intervention of ICD or sudden cardiac (arrhythmic) death; the secondary, appropriate ICD intervention, or death from cardiovascular causes; and the tertiary, appropriate ICD intervention, death or hospitalization for cardiovascular causes.

Discussion

It is expected that appropriate ICD interventions during follow-up will occur more often in patients who had sustained ventricular arrhythmias induced during NIPS.

Clinical trials registry

ClinicalTrials.gov, NCT02373306, date of registration: 26 February 2015.

Natural history of myocardial infarction--relevance for secondary prevention

Numerous variables have been identified as having prognostic value after infarction. The significance of each of these depends both on the time after the event when the observation is made and the length of follow-up. Although much prognostic information has been published, its validity is difficult to establish because the criteria for infarction have seldom been stated, the effect of treatment has been ignored and the case material has been either ill-defined or atypical. Most of the most powerful predictors of medium and long-term prognosis are not susceptible to correction, e.g. age, previous myocardial infarction, cardiomegaly, enzyme levels, intraventricular conduction defects and indices of left ventricular dysfunction. Others, e.g. "warning arrhythmias" may be treatable but there is, as yet, no evidence that suppressing them improves prognosis. The most clinically relevant prognostic factors are those which are of relatively high predictive value but are potentially correctable. These include smoking, hypertension, diabetes, life-threatening arrhythmias, and exercise-induced ischaemia, as manifested by angina and ST changes. Secondary prevention is most likely to be successful if appropriate approaches are aimed at specific subsets. Thus, beta-blockade, anti-arrhythmic therapy, platelet active agents, and surgery may each be beneficial in different although possibly overlapping sub-sets. Even if it is shown that any one of these forms of therapy produces a statistical benefit when given to the whole post-infarct population, it does not follow that it should be given to all members of such a population.

Electropharmacologic effect of a standard dose of intravenous procainamide in patients with sustained ventricular tachycardia

BACKGROUND

Patients with inducible sustained ventricular tachycardia (VT) sometimes receive intravenous procainamide during electrophysiologic testing. Unfortunately, the responses to intravenous and subsequent oral drug therapy are variable and may be discordant.

HYPOTHESIS

It was the aim of this study to determine whether this variability might be explained by heterogeneity in the electropharmacologic response, even in a homogeneous population.

METHODS

We studied 42 patients who had spontaneous malignant ventricular arrhythmia and were inducible to sustained monomorphous VT during electrophysiologic testing. Each received 15 mg/kg of intravenous procainamide followed by a 2 mg/min infusion. Serum levels were drawn immediately following programmed stimulation. The mean procainamide level was 6.7 +/- 1.4 mcg/ml with an N-acetyl procainamide level of 1.0 +/- 0.5 mcg/ml. The 14 procainamide responders (5 of whom were noninducible and 9 whose VT cycle length increased > 100 ms) and the 28 nonresponders had similar procainamide and NAPA levels (6.5 +/- 1.4 vs. 6.7 +/- 1.4 mcg/ml).

RESULTS

There was no significant difference in baseline clinical parameters, His to ventricular electrogram (HV) interval, effective refractory period, or VT cycle length. Prolongation of the effective refractory period and infra His conduction time occurred to a similar extent in responders and nonresponders.

CONCLUSION

We conclude that procainamide has a consistent dose-response relationship with respect to refractoriness and conduction in patients with malignant arrhythmias. However, acute antiarrhythmic efficacy of procainamide cannot be predicted by clinical factors, drug levels, or drug-induced changes in common electrophysiologic parameters.

Assessment of Efficacy of Pharmacotherapy for Ventricular Tachycardia

The presence and sinister prognosis of sustained ventricular tachycardia was recognised early in the twentieth century in patients with serious cardiac disease. Treatment was difficult and evolved slowly. The development of antiarrhythmic drug therapy was frequently based on chance clinical observations and on the assessment of drug effects in animal models of arrhythmia that bore little resemblance to the actual clinical scenarios in which the drugs were to be employed. Even early reports of antiarrhythmic drug use were tempered by awareness of serious adverse side effects. Many drugs were brought into wide-spread clinical use without the background of large randomised trials of efficacy. Assessment of drug efficacy for ventricular tachycardia was frequently based on the effects of an administered drug on inducibility of tachycardia with invasive electrophysiologic techniques. Suppression of inducibility was suggested to be a marker of drug efficacy. Similarly, suppression of spontaneously occurring ventricular ectopic beats was also used as a predictor of drug effect. However, both predictive techniques were hindered by inherent baseline variability. It was subsequently demonstrated that mode of induction of ventricular tachycardia could vary widely at repeat inductions. Antiarrhythmic drugs rarely suppressed inducibility of VT but could alter mode of induction. Techniques were developed to estimate true drug effects by quantitating and allowing for random variability in mode of tachycardia induction. In particular, reproducibility of tachycardia induction was enhanced when baseline and drug studies were performed at short intervals. Even with these techniques, prediction of long-term drug efficacy in individual patients remained difficult and acute drug testing served principally to demonstrate the fact that drug therapy was more likely to facilitate induction of tachycardia than to suppress it (pro-arrhythmic effect). Large clinical trials also demonstrated the potent pro-arrhythmic effects of drug therapy especially when sodium-channel blocking drugs were used. By the end of the twentieth century, antiarrhythmic drugs were used primarily as adjuncts to device therapy for patients at risk of life-threatening ventricular arrhythmias.

Surgery and ablative therapy for ventricular tachycardia

In the absence of acute ischaemia, ventricular tachycardia (VT) is the most common arrhythmia leading to cardiac arrest and death. This paper will describe the history of research into VT and the therapies that evolved. The contributions of John Uther and other members of the Department of Cardiology at Westmead Hospital will be outlined and placed into perspective.

The International Liaison Committee on Resuscitation (ILCOR) consensus on science with treatment recommendations for pediatric and neonatal patients: pediatric basic and advanced life support

This publication contains the pediatric and neonatal sections of the 2005 International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science With Treatment Recommendations (COSTR). The consensus process that produced this document was sponsored by the International Liaison Committee on Resuscitation (ILCOR). ILCOR was formed in 1993 and consists of representatives of resuscitation councils from all over the world. Its mission is to identify and review international science and knowledge relevant to cardiopulmonary resuscitation (CPR) and emergency cardiovascular care (ECC) and to generate consensus on treatment recommendations. ECC includes all responses necessary to treat life-threatening cardiovascular and respiratory events. The COSTR document presents international consensus statements on the science of resuscitation. ILCOR member organizations are each publishing resuscitation guidelines that are consistent with the science in this consensus document, but they also take into consideration geographic, economic, and system differences in practice and the regional availability of medical devices and drugs. The American Heart Association (AHA) pediatric and the American Academy of Pediatrics/AHA neonatal sections of the resuscitation guidelines are reprinted in this issue of Pediatrics (see pages e978-e988). The 2005 evidence evaluation process began shortly after publication of the 2000 International Guidelines for CPR and ECC. The process included topic identification, expert topic review, discussion and debate at 6 international meetings, further review, and debate within ILCOR member organizations and ultimate approval by the member organizations, an Editorial Board, and peer reviewers. The complete COSTR document was published simultaneously in Circulation (International Liaison Committee on Resuscitation. 2005 International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science With Treatment Recommendations. Circulation. 2005;112(suppl):73-90) and Resuscitation (International Liaison Committee on Resuscitation. 2005 International Consensus Conference on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science With Treatment Recommendations. Resuscitation. 2005;67:271-291). Readers are encouraged to review the 2005 COSTR document in its entirety. It can be accessed through the CPR and ECC link at the AHA Web site: www.americanheart.org. The complete publication represents the largest evaluation of resuscitation literature ever published and contains electronic links to more detailed information about the international collaborative process. To organize the evidence evaluation, ILCOR representatives established 6 task forces: basic life support, advanced life support, acute coronary syndromes, pediatric life support, neonatal life support, and an interdisciplinary task force to consider overlapping topics such as educational issues. The AHA established additional task forces on stroke and, in collaboration with the American Red Cross, a task force on first aid. Each task force identified topics requiring evaluation and appointed international experts to review them. A detailed worksheet template was created to help the experts document their literature review, evaluate studies, determine levels of evidence, develop treatment recommendations, and disclose conflicts of interest. Two evidence evaluation experts reviewed all worksheets and assisted the worksheet reviewers to ensure that the worksheets met a consistently high standard. A total of 281 experts completed 403 worksheets on 275 topics, reviewing more than 22000 published studies. In December 2004 the evidence review and summary portions of the evidence evaluation worksheets, with worksheet author conflict of interest statements, were posted on the Internet at www.C2005.org, where readers can continue to access them. Journal advertisements and e-mails invited public comment. Two hundred forty-nine worksheet authors (141 from the United States and 108 from 17 other countries) and additional invited experts and reviewers attended the 2005 International Consensus Conference for presentation, discussion, and debate of the evidence. All 380 participants at the conference received electronic copies of the worksheets. Internet access was available to all conference participants during the conference to facilitate real-time verification of the literature. Expert reviewers presented topics in plenary, concurrent, and poster conference sessions with strict adherence to a novel and rigorous conflict of interest process. Presenters and participants then debated the evidence, conclusions, and draft summary statements. Wording of science statements and treatment recommendations was refined after further review by ILCOR member organizations and the international editorial board. This format ensured that the final document represented a truly international consensus process. The COSTR manuscript was ultimately approved by all ILCOR member organizations and by an international editorial board. The AHA Science Advisory and Coordinating Committee and the editor of Circulation obtained peer reviews of this document before it was accepted for publication. The most important changes in recommendations for pediatric resuscitation since the last ILCOR review in 2000 include: Increased emphasis on performing high quality CPR: "Push hard, push fast, minimize interruptions of chest compression; allow full chest recoil, and don't provide excessive ventilation" Recommended chest compression-ventilation ratio: For lone rescuers with victims of all ages: 30:2 For health care providers performing 2-rescuer CPR for infants and children: 15:2 (except 3:1 for neonates) Either a 2- or 1-hand technique is acceptable for chest compressions in children Use of 1 shock followed by immediate CPR is recommended for each defibrillation attempt, instead of 3 stacked shocks Biphasic shocks with an automated external defibrillator (AED) are acceptable for children 1 year of age. Attenuated shocks using child cables or activation of a key or switch are recommended in children <8 years old. Routine use of high-dose intravenous (IV) epinephrine is no longer recommended. Intravascular (IV and intraosseous) route of drug administration is preferred to the endotracheal route. Cuffed endotracheal tubes can be used in infants and children provided correct tube size and cuff inflation pressure are used. Exhaled CO2 detection is recommended for confirmation of endotracheal tube placement. Consider induced hypothermia for 12 to 24 hours in patients who remain comatose following resuscitation. Some of the most important changes in recommendations for neonatal resuscitation since the last ILCOR review in 2000 include less emphasis on using 100% oxygen when initiating resuscitation, de-emphasis of the need for routine intrapartum oropharyngeal and nasopharyngeal suctioning for infants born to mothers with meconium staining of amniotic fluid, proven value of occlusive wrapping of very low birth weight infants <28 weeks' gestation to reduce heat loss, preference for the IV versus the endotracheal route for epinephrine, and an increased emphasis on parental autonomy at the threshold of viability. The scientific evidence supporting these recommendations is summarized in the neonatal document (see pages e978-e988).

Comparison of arrhythmia recurrence in patients presenting with ventricular fibrillation versus ventricular tachycardia in the Antiarrhythmics Versus Implantable Defibrillators (AVID) trial

Because many episodes of ventricular fibrillation (VF) are believed to be triggered by ventricular tachycardia (VT), patients who present with VT or VF are usually grouped together in discussions of natural history and treatment. However, there are significant differences in the clinical profiles of these 2 patient groups, and some studies have suggested differences in their response to therapy. We examined arrhythmias occurring spontaneously in 449 patients assigned to implantable cardioverter-defibrillator (ICD) therapy in the Antiarrhythmics Versus Implantable Defibrillators (AVID) trial to determine whether patients who receive an ICD after VT have arrhythmias during follow-up that are different from patients who present with VF. ICD printouts were analyzed both by a committee blinded to the patients' original presenting arrhythmia and by the local investigator. During 31 +/- 14 months of follow-up, 2,673 therapies were reported. Patients who were enrolled in the AVID trial after an episode of VT were more likely to have an episode of VT (73.5% vs 30.1%, p <0.001), and were less likely to have an episode of VF (18.3% vs 28.0%, p = 0.013) than patients enrolled after an episode of VF. Adjustment for differences in ejection fraction, previous infarction, and beta-blocker and antiarrhythmic therapy did not appreciably change the results. Ventricular arrhythmia recurrence during follow-up is different in patients who originally present with VT than in those who originally present with VF. These findings suggest there are important differences in the electrophysiologic characteristics of these 2 patient populations.

Evaluation and management of cardiac arrhythmias in the elderly

Cardiac arrhythmias are common in elderly patients. Complete evaluation with detection of underlying structural heart disease and comorbidities is necessary. Prognosis is dependent on the presence of underlying heart disease, particularly the degree of ventricular dysfunction and the presence of comorbidities. Long-term prognosis is excellent in patients without underlying heart disease or severe comorbidities. Management and specific drug therapy in elderly patients with arrhythmias need to be individualized in reference to the underlying cardiac disorder, drug side effects, and the patient's comorbidities.

Matching cardiac rhythm management technology to patient needs: pacing/ablation/implantable cardioverter defibrillators

Data from 2 decades of clinical electrophysiologic studies have allowed great progress in the evaluation and treatment of patients with sustained ventricular arrhythmias and the appropriate identification of those patients at high risk for subsequent sudden death. The goals of treatment of the patient with ventricular arrhythmias are to suppress symptoms and prevent a fatal event. The steps in providing such therapy include (1) defining the cardiac anatomy; (2) assessing arrhythmia risk through noninvasive or invasive testing; and (3) prescribing treatment based on these results. Patients may be separated into high- and low-risk groups to help identify appropriate treatment. Although low-risk groups may benefit from reassurance or medications such as beta-blockers or verapamil, high-risk groups have been more difficult to treat. Recent randomized trials of implantable cardioverter defibrillators (ICDs) for ventricular arrhythmias suggest that they may provide better protection for high-risk patients than do antiarrhythmic medications.

Drug therapy of sustained ventricular tachyarrhythmias. Is there still a role?

This article provides a review of the risks faced by patients with sustained ventricular tachycardia (VT) or ventricular fibrillation (VF) in the absence of a reversible or transient cause so that the goals of therapy can be clearly defined. The therapeutic approaches that have been proposed to achieve these goals are outlined and evidence comparing these various approaches to therapy is then summarized in order to propose an algorithm for the optimal use of antiarrhythmic drug therapies as primary therapy for selected VT/VF patients. Options for the ancillary uses of antiarrhythmic drug therapies in ICD patients are considered.

Evolution of diagnostic and interventional cardiac electrophysiology: a brief historical review

The field of clinical cardiac electrophysiology has evolved dramatically over the last 30 years, beginning with description of the first His bundle recording in 1969. Subsequently, in the early 1970s, more sophisticated diagnostic electrophysiologic techniques were developed to diagnose and guide drug treatment of arrhythmias. These diagnostic techniques were further advanced during the late 1970s and 1980s to electrically map arrhythmias and guide their surgical ablation. Surgical treatments of both supraventricular and ventricular arrhythmias proliferated in the 1970s and 1980s, with overall excellent results. However, because of the morbidity and mortality associated with arrhythmia surgery, it was ultimately replaced in the 1990s by radiofrequency catheter ablation (RFCA) for treatment of most forms of supraventricular tachycardia and idiopathic ventricular tachycardia, and by the automatic implantable cardioverter defibrillator (ICD) for treatment of life-threatening ventricular arrhythmias associated with coronary artery disease and dilated cardiomyopathy. At present, the only arrhythmias that cannot be reliably and safely cured by RFCA are chronic atrial fibrillation and life-threatening ventricular arrhythmias. For chronic atrial fibrillation, new catheter designs are being developed to create linear ablation lines mimicking the curative MAZE operation. For life-threatening ventricular arrhythmias, the ICD has been increasingly utilized as transvenous lead systems and smaller devices have been developed. In the next millennium, new developments that may be expected for treatment of atrial fibrillation and life-threatening ventricular arrhythmias include catheter systems for linear RFCA of atrial fibrillation, ICDs for both atrial and ventricular defibrillation, and biventricular pacing ICDs for patients with congestive heart failure.

Electrophysiologic parameters to predict clinical recurrence of ventricular tachycardia in patients under electrophysiologic study-guided effective pharmacological therapy

Although an electrophysiologic study (EPS) is the most reliable method for selecting the treatment for a patient with sustained ventricular tachycardia (VT), VT recurrence may occur even during EPS-guided effective therapy. Electrophysiologic parameters were compared between patients with and without arrhythmic events under EPS-guided effective therapy to identify the predictive parameters of VT recurrence during the clinical course. The study population consisted of 77 consecutive patients with sustained VT who were receiving long-term pharmacological therapy that was demonstrated to be effective by the EPS assessment. The VT induction protocol employed 1-3 extrastimuli and rapid ventricular pacing at 2 right ventricular sites and 1 left ventricular site, and isoproterenol was infused when VT was not induced. To determine the 'effective' antiarrhythmic drug, all sustained ventricular arrhythmias had to be prevented during the whole induction protocol, but repetitive ventricular responses (RVR) were allowed to remain for up to 5 beats when they were in the same QRS configurations as the clinical VT and up to 12 beats when they were in polymorphic QRS configurations. The effective refractory periods (ERPs) at the 3 ventricular pacing sites and their difference (i.e., ERP-dispersion) and the maximum number of RVR beats were evaluated in an EPS during the control state and at the time of drug assessment. In the comparison of patients with and without VT recurrence, there was no significant difference in clinical characteristics or ERPs, but the deltaERP-dispersion (i.e., the increase in ERP-dispersion caused by the antiarrhythmic drug) and the maximum number of RVRs were significantly smaller in the group of patients without VT recurrence (deltaERP-dis, -3+/-8 vs. 6+/-12, p = 0.0027; maxRVR, 3+/-3 vs. 5+/-4, p = 0.0160). The VT recurrence rate was significantly lower in the patients with deltaERP-dis < or =0 or maxRVR<6 in comparison with the others (p = 0.01 14 and p = 0.0360). Patients with VT recurrence showed greater deltaERP-disp and a longer duration of RVRs at the time of drug assessment in comparison with the patients without VT recurrence. The prognosis of patients under EPS-guided therapy may be improved by the use of stricter criteria for drug assessment in the EPS, although this may decrease the number of drug responders determined in the EPS.

Efficacy of bretylium tosylate for ventricular tachycardia

In 20 patients with inducible ventricular tachycardia (VT), intravenous bretylium tosylate infused as a 10-mg/kg bolus followed by 2 mg/min caused no change in refractory periods and did not suppress inducibility of VT. The use of bretylium for the treatment of VT should be reexamined.

[Current indications for implantable automatic defibrillators]

Since the first implantation in man in 1980 implantable cardioverter defibrillator technology has greatly improved and the number of devices implanted has increased considerably in recent years. Non-thoracotomy lead systems and biphasic shocks are now the approach of choice, offering nearly a 100% success rate. This paper version reviews the current indications for the implantation of implantable cardioverter defibrillator and is an upgraded of an article previously published by the Arrhythmia's Section of the Spanish Society of Cardiology. Recommendations for qualification of centres implanting defibrillators and follow up are also addressed.

Definition of predicted effective antiarrhythmic drug therapy for ventricular tachyarrhythmias by the electrophysiologic study approach: randomized comparison of patient response criteria

OBJECTIVES

We sought to compare efficacies of therapy for ventricular tachyarrhythmias selected by programmed stimulation using two different patient response efficacy criteria: <5 versus <16 repetitive ventricular responses.

BACKGROUND

Therapy selection for ventricular tachyarrhythmias by programmed stimulation requires definition of a patient response that predicts long-term efficacy. Such definitions have not been previously compared prospectively.

METHODS

Patients with sustained ventricular tachyarrhythmias were randomized to therapy selection using either the <5 or <16 repetitive response criterion of predicted effective therapy. The primary end point was sudden death or recurrence of ventricular tachyarrhythmia requiring intervention.

RESULTS

Predicted effective drug therapy was found for 23 (34%) of 68 patients randomized to the <5 criterion and 29 (36%) of 81 patients randomized to the <16 criterion (p = NS). Definition of therapy required 3.0 +/- 1.6 drug trials (mean +/- SD) in patients randomized to the <5 criterion and 2.9 +/- 1.8 trials in patients randomized to the <16 criterion (p = NS). Patients randomized to the <5 criterion had a lower 2-year probability of the primary end point (0.20 +/- 0.05) than did patients randomized to the <16 criterion (0.33 +/- 0.05, one-tailed p = 0.004). The advantage of the <5 criterion was also seen in subgroup analyses involving patients with and without an initial drug efficacy prediction.

CONCLUSIONS

The programmed stimulation approach to the selection of antiarrhythmic therapy for ventricular tachyarrhythmias using a patient response criterion of <5 repetitive ventricular responses results in a lower probability of recurrence of ventricular tachyarrhythmia than does use of a <16 repetitive response criterion.

General principles of antiarrhythmic therapy for ventricular tachyarrhythmias

Sudden cardiac death due to ventricular arrhythmias is a significant cause of mortality in patients with structural heart disease. Over the past several decades, the introduction of new pharmacologic and nonpharmacologic therapy has expanded the treatment options available. This article will focus on the use of antiarrhythmic medication for the treatment of ventricular arrhythmias and will review the following: (1) treatment goals for various clinical populations, (2) the mechanisms of antiarrhythmic and proarrhythmic actions of antiarrhythmic medications, and (3) empiric versus guided pharmacologic therapy.

Arrhythmia risk: electrophysiological studies and monophasic action potentials

Shortly after in the introduction of programmed electrical stimulation (PES) of the heart to study and localize cardiac arrhythmias in the intact human heart, the technique was used for risk stratification of the arrhythmia patient. Two decades later we have to conclude that especially in ventricular arrhythmias the technique of PES did not live up to our expectations and the left ventricular function is a better long-term predictor than the induction of ventricular arrhythmias or the ability to find an antiarrhythmic drug able to prevent the initiation of the classically documented ventricular arrhythmia. Another sobering finding came from the analysis of the characteristics of the patient dying suddenly out-of-hospital, which showed that most of those patients could not be classified before the event as being at high risk using noninvasive or invasive testing, not even in those with a previous cardiac history. Monomorphic action potential (MAP) recordings have been of importance in our understanding of torsade de pointe arrhythmias in congenital and acquired QT prolongation. A major problem in case of a less generalized electrophysiological abnormality is the identification of the appropriate place where to put the MAP-electrode.

The effects of class I drugs on the cycle length of sustained ventricular tachycardia and the signal-averaged electrocardiogram

Evaluation of signal-averaged electrocardiograms (SAECGs) has been reported to be useful for predicting the patients with sustained ventricular tachycardia (SVT) combined with organic heart disease and at high risk for sudden cardiac death. However, the relationship between drug efficacy and SAECGs has not been established. We studied the effects of class I drugs on SVT using SAECGs. The study group consisted of 13 patients with SVT who underwent serial electropharmacologic trials. In 7 trials, SVT could not be induced after administration of class I drugs (group 1). In 17 trials, SVT was still inducible (group 2). Filtered QRS in group 2 were significantly prolonged after administration of class I drugs (p < 0.05). The prolongation of the SVT cycle length was correlated with the prolongation of the original QRS (p < 0.05) and with prolongation of the filtered QRS after administration of class I drugs (p < 0.01). The evaluation of the effects of class I drugs on SAECGs may be useful in predicting the inducibility of SVT and SVT cycle length.

The ESVEM trial: impact on treatment of ventricular tachyarrhythmias. Electrophysiologic Study Versus Electrocardiographic Monitoring

The ESVEM (Electrophysiologic Study Versus Electrocardiographic Monitoring) trial was a prospective, randomized study, initiated in 1983, to compare the outcome of patients in whom antiarrhythmic therapy was guided by serial electrophysiological study with the outcome of patients in whom therapy was guided by electrocardiographic monitoring. In a surprising finding, there was no difference in rates of arrhythmia recurrence or mortality between the two methods. Subsequent reanalyses using more stringent criteria for both methods or a combined assessment have not significantly improved the predictive accuracy of guided therapy. Because drug therapy in each limb was also randomized, a comparison of specific antiarrhythmic agents was also possible: sotalol therapy and the absence of previous antiarrhythmic drug therapy were associated with a reduction in arrhythmia recurrence. Survey data suggest that the results of this trial have influenced clinical practice.

Comparison of procainamide and lidocaine in terminating sustained monomorphic ventricular tachycardia

Efficacy of procainamide and lidocaine in terminating spontaneous monomorphic ventricular tachycardia (VT) was assessed in a randomized parallel study. Patients with acute myocardial infarction and those with poor hemodynamic tolerance of VT were excluded. Procainamide 10 mg/kg was given intravenously with an injection speed of 100 mg/min, and lidocaine was administered at an intravenous dose of 1.5 mg/kg in 2 minutes. Fourteen patients were randomized to lidocaine and 15 to procainamide. Termination occurred in 3 of 14 patients after lidocaine and in 12 of 15 patients after procainamide (p <0.01). Procainamide stopped 8 of 11 VTs not responding to lidocaine, and lidocaine stopped 1 of 1 not responding to procainamde. Of a total of 41 VT episodes, 4 of 15 responded to lidocaine and 20 of 26 to procainamide (p <0.01). Because of VT recurrences, 16 patients could be studied repeatedly with drugs given in the reversed order. This resulted in a total of 55 trials of 79 drug injections. Lidocaine terminated 6 of 31 VTs and procainamide 38 of 48 (p <0.001). The protocol was stopped in 4 cases because of adverse effects. A comparison of the QRS width and QT interval before and at the end of the injection revealed significant lengthening of these values after procainamide but no change after lidocaine. In conclusion, procainamide is superior to lidocaine in terminating spontaneously occurring monomorphic VT.

Management of patients with life-threatening sustained ventricular tachyarrhythmias--the role of guided antiarrhythmic drug therapy

Two recent studies have evaluated the utility of electrophysiologic (EP) testing in the treatment of patients with serious ventricular arrhythmias. The first study compared electrophysiologically guided antiarrhythmic drug therapy with nonguided beta-blocker therapy. Patients without inducible arrhythmias were assigned to oral metoprolol; patients with inducible arrhythmias were randomly assigned to receive either oral metoprolol or EP-guided drug therapy with propafenone, flecainide, disopyramide, sotalol, or amiodarone. Antiarrhythmic drugs were tested in a random order, but amiodarone was always tested last. A total of 170 patients were evaluated; 115 patients had inducible arrhythmias, and 61 patients were randomly assigned to serial drug testing, 54 to metoprolol without invasive testing, and the remainder who were noninducible to empiric metoprolol. The best outcome was observed in patients without inducible arrhythmias, all of whom received metoprolol. There was no difference in outcome between the two groups with inducible arrhythmias, either treated with metoprolol or with EP-guided serial antiarrhythmic drug testing. The second study evaluated survivors of out-of-hospital ventricular fibrillation (VF) without new myocardial infarction. Patients received assessment of left ventricular ejection fraction, Holter monitoring (HM), and EP testing. Only patients with inducible sustained ventricular arrhythmias or with sufficient ambulatory ventricular ectopy were included in the study. Therapy was randomized either to empiric amiodarone or conventional drug therapy guided by EP testing and/or HM. A total of 228 patients were treated, 113 with amiodarone and 115 with conventional antiarrhythmic drug therapy. The composite primary end points were total mortality, documented out-of-hospital resuscitation from recurrent VF, or syncopal implantable cardioverter/defibrillator shock followed by return of consciousness. Patients treated with empiric amiodarone had a better outcome than did patients treated with guided conventional drug therapy. In those patients in whom an implantable cardioverter/defibrillator was used, patients treated with amiodarone had fewer total shocks and fewer syncopal shocks than did patients treated with conventional therapy. Patients with a history of out-of-hospital VF or sustained ventricular tachycardia without inducible ventricular arrhythmias at EP study have the best outcome. Empiric metoprolol is equivalent to conventional antiarrhythmic drug therapy guided by EP testing. Empiric amiodarone is superior to conventional antiarrhythmic drug therapy guided by HM and/or EP testing.

A randomized clinical trial of the noninvasive and invasive approaches to drug therapy for ventricular tachycardia: long-term follow-up of the Calgary trial

Individualized antiarrhythmic drug therapy for patients with ventricular tachyarrhythmias may be selected by the noninvasive approach (suppression of spontaneous ventricular premature beats) or the invasive approach (suppression of ventricular tachyarrhythmias induced at an electrophysiologic study). There is controversy over which approach is superior. From a screened population of 124 patients with symptomatic ventricular tachycardia or ventricular fibrillation, 57 patients with both frequent ventricular premature beats and inducible ventricular tachycardia at baseline were randomized to have chronic therapy selected by either the noninvasive or invasive approach. These patients have now been followed up for a minimum event-free period of 6.5 years. By intention-to-treat, therapy selected by the invasive approach prevented subsequent ventricular tachyarrhythmias better than that selected by the noninvasive approach (6-year probabilities of freedom from symptomatic sustained ventricular tachyarrhythmia recurrence; noninvasive approach, 0.45 +/- 0.10; invasive approach, 0.73 +/- 0.09; p=.02). This advantage of the invasive approach was also evident for the outcome of any ventricular tachyarrhythmia recurrence and for efficacy analyses involving only those patients with a drug-efficacy prediction. We hypothesize that the difference between these results and those of the ESVEM trial are caused, in part, by differences in the characteristics of the enrolled patients and differences in criteria used to define a predicted-effective therapy.

Is a baseline electrophysiologic study mandatory for the management of patients with spontaneous, sustained, ventricular tachyarrhythmias?

Should the patient being treated for spontaneous, sustained ventricular tachycardia (VT) or ventricular fibrillation (VF) routinely undergo a baseline, diagnostic, catheter electrophysiologic (EP) study? The potential patient advantages of such a policy include identification of the tachyarrhythmia-initiating episodes of presumed VT or VF, prediction of the subsequent risk of VT/VF recurrences, identification of VT mechanisms amenable to cure by catheter ablation, assessment of the response of a patient's VT to attempts at pace termination, evaluation of the patient's candidacy for some of the approaches to VT/VF therapy selection, and enhancement of our understanding of the mechanisms and therapeutics of VT/VF. Disadvantages of such a policy include patient discomfort, patient risks, and cost. Recognizing that the decision to perform a baseline catheter EP study in a patient with VT/VF must be based on an individualized, patient-based, risk-benefit analysis; this review details each of the advantages and disadvantages of doing so to identify patient populations for whom a baseline catheter EP study is or is not usually indicated.

Evaluation of end points of serial drug testing in patients with sustained ventricular tachycardia after healing of acute myocardial infarction

Serial electrophysiologic drug testing was used to guide antiarrhythmic therapy in a consecutive series of 150 patients with clinical sustained ventricular tachycardia (VT) or cardiac arrest and inducible monomorphic VT. All patients had coronary artery disease and a history of myocardial infarction. For patients with clinical sustained VT, drug responders and partial drug responders (VT slowed by drug to rate < 150 beats/min, with systolic blood pressure > or = 90 mm Hg) had similar total mortality rates (2-year actuarial survival 100% and 94%, p = NS), which were statistically different from that of patients with drug inefficacy (2-year survival 67%). Partial drug responders had high arrhythmia recurrence rates, similar to those of patients with drug inefficacy. For cardiac arrest survivors, the results of electrophysiologically guided drug testing did not predict prognosis. Patients with a change in mode of VT induction during antiarrhythmic therapy had a favorable prognosis (no deaths during follow-up).

Spontaneous sustained ventricular tachycardia in the Electrophysiologic Study Versus Electrocardiographic Monitoring (ESVEM) Trial

OBJECTIVES

We compared the QRS waveforms of the initial and subsequent complexes of spontaneous sustained monomorphic ventricular tachycardia and the rhythm induced at electrophysiologic study to test the theory that premature ventricular complexes "trigger" spontaneous ventricular tachycardia and that a stable substrate exists such that the spontaneous arrhythmia can be reproduced at electrophysiologic study.

BACKGROUND

Failure rates have been high in several recent studies in which prevention of ventricular tachyarrhythmias was guided by suppression of premature ventricular complexes or induced ventricular tachycardias.

METHODS

Digital waveform analysis was used to distinguish events of ventricular tachycardia initiated by configurationally distinct, possibly triggering, complexes (type 1) from events in which the initial QRS waveforms were identical to subsequent complexes, suggesting no requirement for premature ventricular beats (type 2).

RESULTS

Of 1,102 episodes of spontaneous ventricular tachycardia, 73 (6.6%) were type 1; 1,012 were type 2 (91.8%); and 17 (1.5%) were uncertain. Of 59 patients only 14 (24%) had only type 1 episodes (group 1), whereas 37 patients (63%) had predominantly type 2 events (group 2) (p < 0.0001). Sustained ventricular tachycardia was inducible in all group 1 patients, and in most (57%) the induced rhythm was similar to the spontaneous rhythm. Ventricular tachycardia could not be induced in 7 patients from group 2 (19%), and in 18 patients (49%) the induced and spontaneous rhythms were dissimilar. Recurrence of arrhythmia rates differed according to the guidance method in group 2.

CONCLUSIONS

Discrepancies between observed and predicted modes of initiation of ventricular tachycardia and between spontaneous and induced rhythms could result in inappropriate guidance and subsequent failure of antiarrhythmic treatment.