Out-of-hospital cardiac arrest: electrophysiologic observations and selection of long-term antiarrhythmic therapy

Risk Stratification for Sudden Cardiac Death After Myocardial Infarction

Sudden cardiac death (SCD) accounts for ∼50% of mortality after myocardial infarction (MI). Most SCDs result from ventricular tachyarrhythmias, and the tachycardias that precipitate cardiac arrest result from multiple mechanisms. As a result, it is highly unlikely that any single test will identify all patients at risk for SCD. Current guidelines for use of implantable cardioverter-defibrillators (ICDs) to prevent SCD are based primarily on measurement of left ventricular ejection fraction (LVEF). Although reduced LVEF is associated with increased total cardiac mortality after MI, the focus of current guidelines on LVEF omits ∼50% of patients who die suddenly. In addition, there is no evidence of a mechanistic link between reduced LVEF and arrhythmias. Thus, LVEF is neither sensitive nor specific as a tool for post-MI risk stratification. Newer tests to screen for predisposition to ventricular arrhythmias and SCD examine abnormalities of ventricular repolarization, autonomic nervous system function, and electrical heterogeneity. These tests, as well as older methods such as programmed stimulation, the signal-averaged electrocardiogram, and spontaneous ventricular ectopy, do not perform well in patients with LVEF ≤30%. Recent observational studies suggest, however, that these tests may have greater utility in patients with LVEF >30%. Because SCD results from multiple mechanisms, it is likely that combinations of risk factors will prove more precise for risk stratification. Prospective trials that evaluate the performance of risk stratification schema to determine ICD use are necessary for cost-effective reduction of the incidence of SCD after MI.

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.

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.

Efficacy of procainamide and lidocaine in terminating sustained monomorphic ventricular tachycardia

BACKGROUND

The efficacy of antiarrhythmic drugs in terminating sustained monomorphic ventricular tachycardia (SMVT) was assessed in a retrospective manner to provide a basis for recommending their use.

METHODS AND RESULTS

The 90 patients were included in this study to evaluate the efficacy to terminate SMVT using procainamide or lidocaine. All patients were alert and responsive. The mean systolic blood pressure was 91+/-25 mmHg (range, 40-150 mmHg). SMVT was diagnosed from ECG recordings and later in an electrophysiologic study. VTs with a cycle length of 329+/-55 and 324+/-61 ms were treated with the mean doses of 358+/-50 mg and 81+/-30 mg of procainamide and lidocaine and were terminated in 53/70 (75.7%) and in 7/20 (35.0%) respectively. The drugs were discontinued if there was no rise in blood pressure after slowing of the tachycardia rate or if there were signs of impending deterioration in consciousness. Though procainamide was effective, blood pressure was often low and DC shock should be available at all times during administration of the drug.

CONCLUSIONS

Procainamide, the relatively older drug, was more effective than lidocaine in terminating SMVT associated with structural heart diseases. This is a retrospective analysis but can form the basis for formulating guidelines for initial management of SMVT.

Role of platelets in the development of atherosclerotic disease and possible interference with platelet inhibitor drugs

During the last two decades, significant advances have been made in the understanding of atherosclerotic disease. The pathogenesis of atherosclerosis appears to depend on a precise sequence of critical events based on the interaction of blood elements and lipids with the arterial wall. The major critical events and their sequence appears to be as follows: hemodynamic stress and endothelial injury; arterial wall-platelet interaction; smooth muscle cell proliferation; lipid entry and accumulation; significant arterial narrowing with fibrosis and development of thrombi; and complications in the form of calcification, ulceration, aneurysm, acute thrombotic occlusion and embolization. This sequence of critical events starts at a young age and in all geographic racial groups. Their evolution into advanced symptomatic lesions takes many years and varies in incidence and extent among different geographic and ethnic groups. It appears that in promoting and accelerating this process into the advanced stage of the disease, the presence at a young age of the so-called risk factors of atherosclerotic disease is most important. The recent advances in the understanding of the atherosclerotic process will be highlighted in this chapter with particular attention being focused on the role of platelets and thrombosis in the development of the disease and the possible role of platelet inhibitor drugs on the prevention of coronary atherosclerotic disease.

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.

Long-term survival after successful inhospital cardiac arrest resuscitation

BACKGROUND

Little is known about long-term outcomes of patients who survive inhospital cardiac arrest.

METHODS

We examined long-term survival after inhospital cardiac arrest and whether procedural changes that improved survival to discharge impacted long-term survival. Consecutive inhospital arrests in the Atlanta Veterans Affairs Medical Center (Atlanta, GA) from 1995 to 2004 (n = 732) were retrospectively analyzed. Data regarding the arrest was obtained, including age, left ventricular ejection fraction, medications, and comorbidities, presenting rhythm, location of arrest, code duration, and outcomes. Long-term mortality data was obtained based on chart and Social Security Death Index reviews. Further data was gathered on internal cardioverter-defibrillator presence and use in survivors.

RESULTS

Overall, 49 subjects (6.6%) survived to discharge. Univariate analysis found that ventricular tachycardia/ventricular fibrillation and the use of beta-blockers, angiotensin-converting enzyme inhibitors, and antiarrhythmics at the time of arrest were associated with increased survival, whereas advancing age and comorbidities were associated with a higher risk of mortality. Multivariate analysis determined that age, rhythm, and comorbidities independently affected survival. Implementation of a resuscitation program previously documented to improve survival to discharge did not translate to durable long-term survival. Three-year survival rate after discharge was only 41%. Alternatively, subjects with internal cardioverter-defibrillator showed a 36% improvement in 3-year survival rate to 77% (P = .001).

CONCLUSIONS

Subjects with inhospital cardiac arrest have poor long-term prognoses. A strategy that improved inhospital survival did not alter long-term mortality rate. Thus, survival to discharge may not be a sufficient end point for future resuscitation trials.

Long-term outcome of implanted cardioverter defibrillators in survivors of out-of-hospital cardiac arrest of cardiac origin

BACKGROUND

Little is known about the long-term outcome of implantable cardioverter defibrillator (ICD) therapy in survivors of out-of-hospital cardiac arrest (OHCA).

METHODS AND RESULTS

The frequency of lethal ventricular arrhythmias and whether ICD implantation can prevent recurrence of cardiac arrest were examined. Long-term (24.4+/-11.9 months) outcome was examined in 23 patients with OHCA who were treated with an ICD (OHCA group) and 35 patients without OHCA (non-OHCA group) who were treated with an ICD. Patients in both groups had same clinical backgrounds; however, those in the OHCA group showed a significantly lower incidence of induced ventricular arrhythmias (71%) than the non-OHCA group (96%). In the follow-up period, patients in the OHCA group had almost the same incidence of ICD discharge (30%) as patients in the non-OHCA group (40%). The rate of recurrence of ventricular fibrillation in the OHCA patients was 13%, and it was difficult to estimate the rate by induced ventricular arrhythmia.

CONCLUSION

The results suggest that ICD implantation for survivors of OHCA with favorable neurological recovery might be effective for preventing recurrence of cardiac arrest.

Infarct morphology identifies patients with substrate for sustained ventricular tachycardia

OBJECTIVES

We sought to evaluate whether infarct size characterization by cardiac magnetic resonance imaging (MRI) is a better predictor of inducible ventricular tachycardia (VT) than left ventricular ejection fraction (LVEF).

BACKGROUND

Inducibility of VT at electrophysiologic study (EPS) and low LVEF can identify patients with a substrate for VT. Magnetic resonance imaging has been shown to identify, with high precision, areas of myocardial infarction and may therefore be a better tool to evaluate for a substrate for VT.

METHODS

We studied 48 patients with known coronary artery disease who were referred for EPS using cine and gadolinium-enhanced MRI. Wall motion and infarct characteristics were determined blindly and compared among patients with no inducible ventricular arrhythmias (n = 21), those with inducible monomorphic VT (MVT, n = 18), and those with either inducible polymorphic VT or ventricular fibrillation (n = 9).

RESULTS

Patients with MVT had larger infarcts than patients who did not have inducible arrhythmias (mass: 49 +/- 5 g [SE] vs. 28 +/- 5 g, p < 0.005; surface area: 172 +/- 15 cm(2) vs. 93 +/- 14 cm(2), p < 0.0005). Patients with polymorphic VT/fibrillation had intermediate values (mass: 36 +/- 7 g; surface area: 115 +/- 22 cm(2)). Ejection fraction was inversely related to infarct mass and surface area, with R(2) values ranging from 0.21 to 0.27. Logistic regression and receiver-operating characteristic analysis demonstrated that infarct mass and surface area were better predictors of inducibility of MVT than LVEF.

CONCLUSIONS

Infarct surface area and mass, as measured by cardiac MRI, are better identifiers of patients who have a substrate for MVT than LVEF. Further evaluation of infarct size characterization by cardiac MRI as a predictor of sudden cardiac death is warranted.

Myocardial Ischemia and Induction of Sustained Ventricular Tachyarrhythmias:

INTRODUCTION

This study examined the relationship between dobutamine facilitation of ventricular tachyarrhythmia (VT) inducibility with programmed electrical stimulation (PES) and dobutamine stress-induced myocardial ischemia.

METHODS AND RESULTS

Twenty patients with prior myocardial infarction and cardiac arrest or sustained VT but no sustained VT induced at baseline electrophysiologic testing underwent repeat PES during dobutamine infusion. Ischemia (new or worsened wall-motion abnormality) was documented by echocardiography performed in conjunction with PES. Eight patients were receiving Class I or III antiarrhythmic drugs and seven beta-blockers. Dobutamine facilitated induction of sustained VT in 16 patients (80%) and provoked ischemia in 13 patients (65%). Induction of VT was associated with ischemia in 9 patients (56%). VTs associated with ischemia were induced at higher dobutamine doses (26 +/- 11 vs 11 +/- 10 microg/kg per min, P = 0.02) than were VTs without ischemia (n = 7). Among 13 patients with provoked ischemia, 9 (69%) had VTs induced and 4 remained noninducible. The onset of ischemia occurred at the same dose as induction of VT in 5 patients and at a lower dose in 4 patients. Monomorphic VT (318 +/- 59 ms) was induced in 13 patients, of whom 8 (62%) had ischemia. The ECG morphology of VT suggested an origin in a myocardial segment that demonstrated initial viability at low doses then ischemic dysfunction at higher doses preceding VT induction in 7 (88%) of 8 patients.

CONCLUSION

Dobutamine enhances inducibility of sustained VTs during PES. The temporal and anatomic association of dobutamine-induced ischemia and VT suggests that at high dobutamine doses, ischemia may contribute to ventricular arrhythmia inducibility in some patients.

Outcomes and in-hospital treatment of out-of-hospital cardiac arrest patients resuscitated from ventricular fibrillation by early defibrillation

OBJECTIVE

To describe and evaluate the in-hospital treatment of ventricular arrhythmias and underlying structural heart disease in patients who survive ventricular fibrillation (VF) out-of-hospital cardiac arrest (OHCA) in a region with a high survival rate after hospital discharge.

PATIENTS AND METHODS

The study included all patients presenting in Olmsted County, Minnesota, who had experienced OHCA between November 1990 and December 2000 and who underwent defibrillation of VF by an emergency medical service system.

RESULTS

Of 200 patients who experienced VF arrest, 138 (69%) survived to hospital admission (7 died in the emergency department before admission), and 79 (40%) were discharged. Of patients who were discharged, 37 (47%) had a reversible cause of the arrest (perimyocardial infarction) and received treatment of the primary process. The other 42 patients who were discharged had ischemic coronary heart disease (CHD) (n=25), nonischemic CHD (n=10), or idiopathic VF (n=7). Four of the patients with CHD but no left ventricular dysfunction were treated with coronary artery bypass grafting or percutaneous coronary intervention alone. A total of 52 patients (66%) were candidates for electrophysiologic testing. Of these patients, 48 (92%) underwent electrophysiologic testing; of these patients, 10 received amiodarone alone, and 35 received an implantable cardioverter-defibrillator (ICD) (of whom 3 also received amiodarone). Patients who did not receive ICD therapy typically presented before 1998 with CHD and underwent coronary artery bypass grafting or percutaneous coronary intervention only. Of 79 patients who were discharged, 14 (18%) with an ICD have received subsequent shocks. Nineteen (24%) of 79 patients have died, 5 of a primary cardiac etiology (including 2 with repeated OHCA).

CONCLUSIONS

The VF OHCA survival rate is high in the setting of rapid defibrillation, with 40% of patients being discharged from the hospital. By the end of the 10-year study, more patients were receiving antiarrhythmic therapy, in particular ICD implantation, after hospital admission. Overall, the long-term survival in patients with VF OHCA is favorable.

Are electrophysiological studies needed prior to defibrillator implantation?

At present, patients with documented sustained VT or resuscitated cardiac arrest (CA) are treated with ICDs. The aim of this study was to retrospectively evaluate if a routine electrophysiological study should be recommended prior to ICD implantation. In 462 patients referred for ICD implantation because of supposedly documented VT (n = 223) or CA (n = 239), electrophysiological study was routinely performed. In 48% of the patients with CA, sustained VT or VF was inducible. Electrophysiological study suggested conduction abnormalities (n = 11) or supraventricular tachyarrhythmias (n = 3) in conjunction with severely impaired left ventricular function to have been the most likely cause of CA in 14 (5.9%) of 239 patients. Likewise, sustained VT was only inducible in 48% of patients with supposedly documented VT. Of these inducible VTs, nine were diagnosed as right ventricular outflow tract tachycardia or as bundle branch reentry tachycardia. Supraventricular tachyarrhythmias judged to represent the clinical event were the only inducible arrhythmia in 35 (16%) patients (AV nodal reentrant tachycardia [n = 7], AV reentry tachycardia [n = 4], atrial flutter [n = 19], and atrial tachycardia [n = 5]). Based on findings from the electrophysiological study, ICD implantation was withheld in 14 (5.9%) of 239 patients with CA and in 44 (19.7%) of 223 patients with supposedly documented VT. During electrophysiological study, VT or VF was only reproducible in about 50% of patients with supposedly documented VT or CA. Electrophysiological study revealed other, potentially curable causes for CA or supposedly documented VT in 12.6% (58/462) of all patients, indicating that ICD implantation can potentially be avoided or at least postponed in some of these patients. Based on these retrospective data, routine electrophysiological study prior to ICD implantation seems to be advisable.

Clinical characteristics of induced nonclinical ventricular tachycardia in nonischemic cardiomyopathy

The clinical significance of induced nonclinical ventricular tachycardia (NCVT) in nonischemic dilated cardiomyopathy (DCM) remains controversial. Twenty-eight patients with sustained VT or ventricular fibrillation related to DCM underwent programmed ventricular stimulation (PVS) to induce VT. However, VT was not induced in four patients. Based on the morphology of induced ventricular arrhythmia, we classified the remaining 24 patients into NCVT (n = l1 ) and clinical VT (CVT) groups (n = 13), then evaluated the prognosis for a mean follow-up period of 22 months. The cycle length of induced NCVT was significantly shorter than that of induced CVT (277 +/- 38 ms vs 325 +/- 63 ms, P < 0.05). Appropriate antiarrhythmic agents were selected by serial PVS in 36% of the NCVT group and in 38% of the CVT group (4/11 vs 5/13). Among patients who had been treated by PVS guided drug therapy, arrhythmic events were observed in 75% of the NCVT group and 80% of the CVT group (3/4 vs 4/5). The total incidence of sudden death in the NCVT group was higher than that in the CVT group (5/11: 45% vs 4/13: 31%). In conclusion, induced NCVT and CVT are refractory to pharmacological therapy and both have an important characteristic value in DCM.

Prognostic value of baseline electrophysiology studies in patients with sustained ventricular tachyarrhythmia: the Antiarrhythmics Versus Implantable Defibrillators (AVID) trial

OBJECTIVES

We sought to determine the value of electrophysiology (EP) testing in patients with ventricular fibrillation (VF), ventricular tachycardia (VT) with syncope, or sustained VT in the setting of left ventricular dysfunction.

BACKGROUND

Traditionally, EP testing is part of the workup of patients with sustained VT or VF. Recently, some have suggested that EP testing is unnecessary in these patients, many of whom are likely to receive an implantable cardioverter-defibrillator (ICD).

METHODS

Within a multicenter trial (Antiarrhythmics Versus Implantable Defibrillators) designed to evaluate whether drugs or ICD resulted in a better outcome, data were analyzed regarding EP testing. Although this testing was not required, it was performed in >50% of patients. Information regarding the results of EP testing was correlated to baseline clinical characteristics and outcome.

RESULTS

Of 572 patients subjected to an EP test, 384 (67%) had inducible sustained VT or VF. Inducible patients were more likely to have coronary artery disease, previous infarction, and VT as their index arrhythmic event. Inducibility of VT or VF did not predict death or recurrent VT or VF.

CONCLUSIONS

Information derived from EP testing in this patient population, particularly those with VF, is of limited value and may not be worth the risks and costs of the procedure, particularly in those patients likely to receive an ICD.

[Usefulness of the implantable subcutaneous recorder in the diagnosis of recurrent syncope of unknown etiology in patients without structural heart disease and negative tilt test and electrophysiological study]

BACKGROUND AND OBJECTIVES

In up to 38% of the cases, the etiology of syncope difficult to determine. The main obstacle for diagnosis of the causes of syncope lies in the unpredictable frequency of episodes. Development of implantable loop recorders allows long term electrocardiographic monitoring. The aim of this study was to evaluate the usefulness of the implantable loop recorder for the diagnosis of recurrent syncope of unknown origin.

PATIENTS AND METHODS

From May 1991 to April 1999, a cohort of 176 patients with recurrent syncope was prospectively assessed. Investigations, including Holter monitoring, Tilt Test and electrophysiological study, allowed the determination of the etiology in 161 patients. The remaining 15 patients, without structural cardiac disease were selected for continuous electrocardiographic monitoring using an implantable loop recorder.

RESULTS

During follow up after implant, 15 +/- 2 months (X- +/- SEM), 9 patients showed recurrence of symptoms concordant with prior episodes (time: 105 +/- 30 days). In 7 cases records during symptoms were diagnostic (0.47; CI 95%: 0.21-0.73), in 3 cases a diagnosis with documented arrhythmia was achieved, and in 4 other cases a presumptive clinical diagnosis of non-arrhythmic cause was made. In 8 patients, 6 with no recurrences, diagnosis was not possible. There were no complications related to the use of the device.

CONCLUSIONS

The strategy of long term monitoring with the implantable loop recorder is safe and effective in patients with recurrent syncope of unknown etiology.

Catheter ablation of ventricular tachycardia related to coronary artery disease: the role of noncontact mapping

There are a number of limitations associated with conventional mapping for ablation of ventricular tachycardia (VT) in ischemic heart disease, such as the high recurrence rates after initially successful ablation. The development of a noncontact mapping system capable of producing high-resolution isopotential maps of the entire left ventricle has enabled rapid identification of diastolic activity that maintains VT for ablation. With this system it is possible to map nonsustained and fast unstable as well as stable VTs. In this article we review the historic background and concepts of noncontact mapping, its clinical application, and the results of ablations for human VT guided by this mapping system.

Interaction of septadian and circadian rhythms in life-threatening ventricular arrhythmias in patients with implantable cardioverter-defibrillators

Previous studies have shown that life-threatening ventricular arrhythmias display both circadian and septadian (day of the week) periodicity. We hypothesized that assessing the relation between these circadian and septadian rhythms may provide important pathophysiologic information about the mechanism of sudden cardiac death. Using the database from a population of 683 consecutive patients with a third-generation implantable cardioverter-defibrillator (ICD), we examined the time pattern of ICD activations for rapid (prospectively defined as cycle length <280 ms) tachycardias for each day of the week. A total of 5,270 arrhythmic episodes were analyzed. Despite the fact that event distribution was significantly nonuniform (p <0.001) for both circadian and septadian analyses, the circadian pattern was strikingly similar for each day of the week with a relatively broad peak between 9 A.M. and 6 P.M. and a long nadir between 9 P.M. and 6 A.M. We conclude that the trigger factors responsible for the daily circadian distribution of life-threatening ventricular arrhythmias in a population with ICDs are similar throughout the week and may thus be unrelated to the standard work week. These data suggest that the physiologic modulators of circadian and septadian rhythms may be different.

Prevalence, therapeutic response, and outcome of ventricular tachycardia in the out-of-hospital setting: a comparison of monomorphic ventricular tachycardia, polymorphic ventricular tachycardia, and torsades de pointes

OBJECTIVE

To investigate out-of-hospital ventricular tachycardia (VT) cardiac arrest patients, comparing the prevalences and outcomes of the following VT subtypes among this population: monomorphic VT (MVT), polymorphic VT (PVT), and torsades de pointes (TdP, PVT with a prolonged QT interval).

METHODS

This was a retrospective review from a fire department-based paramedic system of nontraumatic VT cardiac arrest patients (January 1991 to December 1994) with a supraventricular perfusing rhythm (SVPR) at some time during out-of-hospital care, with a measurable QT interval. QT interval was measured from an SVPR, and corrected QT interval (QTc) was calculated and considered prolonged if > 0.45 sec. VT was classified as polymorphic or monomorphic. TdP was defined as PVT with a prolonged QT interval.

RESULTS

196 patients were identified; six were excluded due to incomplete medical records, leaving 190 who met inclusion criteria and were used for data analysis. 117 (62%) patients had MVT, while 73 (38%) patients had PVT; of the 73 patients with PVT, 37 (51%) had normal QTc (non-TdP PVT) and 36 (49%) had prolonged QTc (TdP PVT). 97 (51%) patients had prolonged QTc (PQTc). Regardless of VT type (i.e., MVT vs PVT), 97 (51%) patients had prolonged QTc, with a mean QTc of 0.476+/-0.15 seconds prearrest and 0.464+/-12 seconds postarrest. Patients with PQTc were not more likely to have PVT (70 [37%] vs 76 [40%]; p = 0.705). No significant difference with respect to paramedic-witnessed arrests in each VT morphology group and each QT group was found. The overall hospital discharge rate was 28.4%. Regardless of VT type, patients had similar rates of out-of-hospital return of spontaneous circulation (ROSC) and hospital discharge; patients with PQTc were less likely to be discharged from the hospital (19.6% vs 37.6%; p = 0.01). 27.8% of TdP and 26.8% of non-TdP patients were discharged (p = 0.912).

CONCLUSIONS

In this population of out-of-hospital VT arrest patients, MVT is the most common form of VT encountered; PVT and the subtype TdP are also seen in this population with approximately equal frequencies. All three rhythm types demonstrate similar responses to standard Advanced Cardiac Life Support therapy with equal rates of out-of-hospital ROSC and hospital discharge. PQTc may be a marker of poor clinical outcome in patients with out-of-hospital VT arrest.

Secondary prevention of sudden death: the Dutch Study, the Antiarrhythmics Versus Implantable Defibrillator Trial, the Cardiac Arrest Study Hamburg, and the Canadian Implantable Defibrillator Study

Although indisputably effective in the prevention of sudden death, use of implantable cardioverter defibrillator (ICD) therapy may not necessarily affect all-cause mortality, as most patients at risk also present with severely depressed left ventricular dysfunction. Correction of the sudden death risk in these patients creates a new clinical condition in need of a careful assessment. Should all-cause mortality be affected by the expected reduction in sudden death rate associated with ICD therapy, issues of critical importance, such as the time extent of life prolongation and the associated quality of life, still remain to established. To investigate the potential benefit of ICD therapy compared with antiarrhythmic drug treatment, 4 prospective studies--the Dutch trial, the Antiarrhythmics Versus Implantable Defibrillators (AVID) study, the Cardiac Arrest Study Hamburg (CASH), and the Canadian Implantable Defibrillator Study (CIDS)--have been conducted in which patients with documented sustained ventricular arrhythmia were randomized to 1 of these 2 treatment strategies. The enrollment criteria differed in these 4 studies: (1) in the Dutch trial, they included cardiac arrest secondary to a ventricular arrhythmia, old (> 4 weeks) myocardial infarction, and inducible ventricular arrhythmia; (2) in AVID and CIDS, ventricular fibrillation or poorly tolerated ventricular tachycardia; and (3) in CASH, cardiac arrest secondary to a ventricular arrhythmia regardless of the underlying disease. With regard to the antiarrhythmic drugs, the Dutch trial tested class I and III agents, whereas AVID and CIDS compared ICD therapy with class III agents (mostly amiodarone). In CASH, 3 drug subgroups were investigated: propafenone, amiodarone, and metoprolol. All trials used all-cause mortality as the primary endpoint. Data from these trials provide support for ICD as a therapy superior to antiarrhythmic drugs in prolonging survival in patients meeting the entry criteria. This review briefly summarizes the methods, results, limitations, and clinical implications of these 4 studies.

Ventricular arrhythmias in the elderly

Sudden cardiac death (SCD) remains a significant medical problem in the United States. The incidence of SCD increases with advancing age because cardiovascular disease is more prevalent in the elderly. Management of ventricular arrhythmias in the elderly patient is especially challenging because of increased risk of interventional and pharmacologic therapies, altered pharmacokinetics of drugs, and sometimes unclear long-term benefits.

Lack of benefit of very short basic drive train cycle length or repetition of extrastimulus coupling intervals for induction of ventricular tachycardia

INTRODUCTION

There are considerable variations of uncertain importance in basic drive train cycle lengths and degree of repetition of extrastimuli used in programmed ventricular stimulation protocols in different laboratories. We compare prospectively three different stimulation protocols to examine the influence of a short basic drive train cycle length and repetition of extrastimuli on induction of ventricular tachycardia.

METHODS AND RESULTS

Thirty consecutive patients who had documented ventricular tachycardia or fibrillation based on underlying coronary artery disease underwent programmed ventricular stimulation with each of the three study protocols. Protocol A used a basic drive train cycle length of 400 msec with each extrastimulus coupling interval delivered only once. Protocol B used the same basic drive train cycle length, but with each extrastimulus coupling interval repeated three times before decrementing. Protocol C used 300 msec as the cycle length of basic drive trains without repetition of extrastimuli. Sixty-three percent, 67%, and 63% of the study patients had ventricular tachycardia inducible with protocols A, B, and C, respectively (P = NS). Ventricular fibrillation was induced in 23% of the 30 patients in all three protocols. There were no significant differences in the mean cycle lengths of induced ventricular tachycardia, the number of extrastimuli used, and the coupling interval of the last extrastimulus inducing ventricular tachycardia among the three protocols.

CONCLUSION

This study showed no clinical benefit for repetition of extrastimuli that have failed to induce a ventricular tachyarrhythmia during programmed ventricular stimulation. A short basic cycle length of 300 msec was not superior to 400 msec for induction of ventricular tachyarrhythmias. We recommend the use of basic cycle length 400 msec with delivery of each extrastimulus interval only once as the initial protocol for programmed ventricular stimulation.

Late outcome of survivors of idiopathic ventricular fibrillation

This report describes clinical, hemodynamic, and electrophysiologic characteristics of 18 consecutive survivors of sudden cardiac arrest due to idiopathic ventricular fibrillation (VF) between 1986 and 1996. Long-term data in relation to the prescribed therapy are presented. The mean age of the 18 patients was 48 +/- 14 years (median 49). Electrophysiologic studies showed a low inducibility of sustained ventricular tachyarrhythmias in 4 patients (22%). Treatment consisted of class III agents, beta blockers, or implantable cardioverter-defibrillators. Two patients were discharged without any therapy. Therapy control was undertaken either by serial drug testing or by the empirical approach. Serious complications of therapy occurred in 2 patients: 1 patient experienced a proarrhythmic effect of antiarrhythmic drug therapy, and the other patient received multiple inadequate defibrillator discharges due to a defect in the transvenous lead. All but 1 patient (94%) remained free of recurrences of sudden cardiac arrest during a follow-up time of 45 +/- 29 months (median 41). One patient died 2 weeks after surviving cardiac arrest due to intractable VF while receiving sotalol treatment. Therapy guided by electrophysiologic studies did not have any impact on survival. Adverse effects or noncompliance led to discontinuation of drug therapy in 7 patients after a mean period of 31 +/- 30 months. Without any treatment 9 patients remained without recurrences over 45 +/- 33 months. Because of the absence of risk factors for arrhythmia recurrence and criteria to select therapy, randomized prospective studies are warranted to assess the optimal therapies in these young, ostensibly healthy patients.

[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.

[Holter monitoring and programmed ventricular stimulation]

Long-term ECG recordings are the method of choice to evaluate quantity and quality of spontaneous rhythm disturbances. However, this method is limited by the variability of the arrhythmias. Invasive procedures such as programmed stimulation allow the provocation of tachyarrhythmias. Indications for both methods are diagnostic clarification of clinical symptoms, risk stratification with respect to arrhythmogenic sudden cardiac death as well as the control of antiarrhythmic therapy.Due to the high variability of spontaneous complex ventricular arrhythmias, Holter monitoring often fails to document the cause of severe symptoms such as syncope or sudden cardiac death. In these patients, invasive electrophysiological testing is required to provoke the arrhythmia.The prognostic significance of spontaneous ventricular arrhythmias recorded during ambulatory monitoring depends on the underlying cardiac disease. In patients with coronary artery disease and a history of myocardial infarction there is evidence that frequent single and/or complex ventricular extrasystoles indicate an increased risk of sudden cardiac death, especially in the presence of a reduced left ventricular function. In these patients, programmed ventricular stimulation can further characterize a highrisk group.For the management of antiarrhythmic therapy in symptomatic patients, under certain conditions both methods appear to be helpful. For the majority of these patients, however, the invasive electrophysiologic study should be preferred.Thus, long-term ECG recordings and programmed electrical stimulation are no competing, but complementary methods in clinical cardiology.

Arrhythmias in hypertrophic cardiomyopathy

Supraventricular and ventricular arrhythmias, particularly nonsustained ventricular tachycardia, and ventricular premature beats are a common finding in patients with hypertrophic cardiomyopathy. Several investigations have demonstrated that nonsustained ventricular tachycardia on Holter monitoring is associated with an increased risk of sudden cardiac death. It has been a long lasting controversial discussion whether suppression of these arrhythmias with drugs, such as amiodarone is capable to reduce the incidence of sudden cardiac death. While recent studies have indicated that nonsustained ventricular tachycardia in asymptomatic patients without additional risk factors, such as a positive family history of sudden cardiac death or syncope should not be treated prophylactically with amiodarone. Symptomatic patients with sustained ventricular tachycardias and/or syncope related to ventricular arrhythmias should undergo ICD implantation. The implantation of an ICD in asymptomatic patients should be limited to those who have several risk factors for sudden cardiac death. It is questionable whether other risk stratifiers, such as programmed electrical stimulation may be helpful to identify asymptomatic patients who are at risk to die suddenly. Moreover, whether the demonstration of electrocardiogram fractionation during electrophysiological study is superior to the induction of sustained ventricular arrhythmias for risk stratification, needs further investigation.

Evaluation and treatment strategies in patients at high risk of sudden death post myocardial infarction

Over 50 percent of deaths in patients who survive an acute myocardial infarction are due to fatal ventricular tachyarrhythmias. Patients who survive an episode of sustained ventricular arrhythmia are at highest risk of recurrent cardiac arrest. Electrophysiologic studies have been found to be useful in guiding therapy and reducing mortality in these patients and in patients with syncope due to arrhythmic etiology. Evaluation and treatment of nonsustained ventricular tachycardia post infarction remains somewhat controversial. A recently published trial (MADIT), however, showed improved survival with an implanted defibrillator in patients with coronary disease and asymptomatic nonsustained ventricular tachycardia. Asymptomatic patients post infarction at high risk include those who have significant left ventricular dysfunction, late potentials, high-grade ventricular ectopy, and abnormal heart rate variability. These tests individually, however, have a low positive predictive accuracy. This, combined with the fact that antiarrhythmic drugs are frequently not effective and can be proarrhythmic, leaves the best treatment for these patients uncertain. It is known, however, that beta-adrenoreceptor blocking agents do reduce mortality after an acute myocardial infarction. Early studies have shown mixed results relating to sudden death and total mortality with amiodarone. To date, no other antiarrhythmic drug has shown benefit, while several have been shown to be harmful. Recent studies have also shown some beneficial effects of angiotensin-converting enzyme inhibitors, carvedilol, a third-generation beta-blocking agent with vasodilator properties, and the angiotensin II receptor antagonist losartan. However, their precise role in reducing sudden death needs to be defined further.

Can catheter ablation in cardiac arrest survivors prevent ventricular fibrillation recurrence?

Ventricular tachyarrhythmias are the most common cause for sudden cardiac death. The success of catheter ablation for supraventricular tachycardias led to the supposition that ablation could also be used in the treatment of ventricular tachycardias. Despite the promising results in bundle branch reentry and some forms of idiopathic ventricular tachycardia, the success rate in patients with coronary artery disease is still low. There is hope that new approaches to reliably localize the critical region of the tachycardia and new ablation techniques to create larger areas of injury may lead to a wider application of ablation therapy in the treatment of ventricular tachycardia. Survivors of cardiac arrest typically have more rapid and unstable arrhythmias than patients with sustained ventricular tachycardia, and these rapid arrhythmias frequently degenerate into ventricular fibrillation. The instability of the arrhythmia makes it impossible to localize the arrhythmia origin with current mapping techniques. Experimental and clinical data, however, suggest that these arrhythmias also frequently start from a localized area of electrical activation. With developments in mapping techniques and energy delivery, catheter ablation may soon become a feasible therapeutic approach in some patients with unstable arrhythmias. The article discusses the prerequisites for this approach and suggests the patients who may be appropriate candidates for this technique.

Suppression of inducible ventricular arrhythmias by intravenous azimilide in dogs with previous myocardial infarction

The class III antiarrhythmics azimilide dihydrochloride and dl-sotalol were evaluated for ability to suppress induction of ventricular tachyarrhythmias (VT) in anesthetized, male mongrel dogs 4-6 days after surgical infarction of the left ventricle (LV) produced by ligation/reperfusion of the left anterior descending coronary artery. Postmortem infarcts averaged 28.2 +/- 3.3% and 27.5 +/- 3.9% of the LV for azimilide- and sotalol-treated dogs, respectively. Both agents (0.3-30 mg/kg i.v.) increased ventricular effective refractory period as a function of dose in LV normal and infarcted zones without increasing conduction time. Azimilide was well tolerated hemodynamically up to 30 mg/kg i.v., whereas sotalol produced a significant and dose-related decrease in both blood pressure and heart rate. Azimilide was effective in five (56%) of nine dogs in preventing induction of ventricular arrhythmias by programmed electrical stimulation (PES) at doses from 1 to 30 mg/kg. Efficacy was seen for nonsustained and sustained VT and for ventricular fibrillation. Although sotalol (0.3-10 mg/kg) was effective in all five VT dogs tested, one of two nonsustained ventricular tachyarrhythmia (NSVT) dogs and two of three sustained ventricular tachyarrhythmia (SVT) dogs were reinducible with the baseline arrhythmia at doses higher than the effective dose, and one dog died after 30 mg/kg of sotalol. Both agents increased the cycle length of VT. Thus azimilide simultaneously increased refractoriness and provided antiarrhythmic efficacy as suppression of PES-induced ventricular arrhythmias in infarcted dogs without the hemodynamic depression seen with sotalol.

Increased Monday incidence of life-threatening ventricular arrhythmias. Experience with a third-generation implantable defibrillator

BACKGROUND

Examination of the timing of cardiac events provides important pathophysiological information. Previous studies have shown that the onset of acute myocardial infarction occurs most frequently on Monday. The septadian (day of the week) pattern of occurrence of sudden cardiac death and lethal ventricular arrhythmias has not been examined previously.

METHODS AND RESULTS

We examined the septadian distribution of life-threatening (cycle length < 280 ms) ventricular arrhythmias in 683 consecutive patients receiving a Ventak PRx, a third-generation implantable defibrillator with an event recorder. There was a prominent Monday peak, with a midweek decline and a secondary peak later in the week. A marked trough is apparent on both weekend days. The observed pattern was independent of age, sex, ejection fraction, NYHA functional class, type of heart disease, and the use of antiarrhythmic drugs but was not observed in patients receiving beta-blockers.

CONCLUSIONS

Potentially lethal arrhythmias are not random events but occur in a daily pattern suggesting a relationship to the beginning and end of the work week. The absence of a Monday peak in patients receiving beta-blockers suggests that the pattern may be influenced by beta-blockers. This information may be useful in devising strategies to prevent sudden cardiac death.

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.

Management of ventricular fibrillation with transvenous defibrillators without baseline electrophysiologic testing or antiarrhythmic drugs

INTRODUCTION

Baseline electrophysiologic study (EPS) is routinely performed in patients resuscitated from ventricular fibrillation (VF) to risk stratify and select patients for chronic antiarrhythmic drug therapy. The role of EP testing prior to insertion of a multiprogrammable implantable cardioverter defibrillator (ICD), however, is unclear.

METHODS AND RESULTS

This study was a retrospective review of outcome in 66 survivors of an initial episode of out-of-hospital VF not associated with a Q wave myocardial infarction or reversible causes, treated with transvenous ICDs as first-line therapy. Patients were excluded from the study if they had a previous history of monomorphic ventricular tachycardia (VT), a clinical history suggestive of supraventricular tachycardia, or had undergone preoperative EP testing. Fifty-two of the patients (79%) were male with an average age of 58 +/- 11 years. Coronary artery disease was present in 43 patients (66%), cardiomyopathy in 15 patients (23%), and valvular heart disease in 1 patient (1.5%). Seven patients (11%) had no detectable structural heart disease. The mean left ventricular ejection fraction was 0.40 +/- 0.16. With an average follow-up of 25 +/- 12 months, survival free of death from any cause was 100%. Twenty-three patients (35%) experienced 48 episodes of recurrent rapid VT or VF (average cycle length: 236 +/- 47 msec) treated by their device. The mean time to first therapy was 223 +/- 200 days. Only one of these patients also received antitachycardia pacing for two episodes of VT. One patient (1.5%) temporarily received amiodarone after removal of an infected device that was subsequently replaced. No other patient received antiarrhythmic drug therapy.

CONCLUSION

After a cardiac arrest due to primary VF, select patients treated with multiprogrammable ICDs can be managed successfully without baseline EPS or antiarrhythmic drug therapy.

Influence of Holter monitor and electrophysiologic study methods and efficacy criteria on the outcome of patients with ventricular tachycardia and ventricular fibrillation in the ESVEM trial

Because not all laboratories use the monitoring and stimulation protocols used in the Electrophysiologic Study Versus Electrocardiographic Monitoring (ESVEM) trial, we reanalyzed the ESVEM patients' data using alternative, commonly used Holter monitor (HM) and programmed stimulation efficacy criteria to determine if different criteria would have changed the trial's conclusions. Also, because beta-blocker use and coronary artery disease frequency were not equally distributed between the two limbs in ESVEM, we reanalyzed the ESVEM data adjusting for the possible effect of these variables. In the HM limb, drug efficacy in the original ESVEM analysis was declared by reduction of total premature ventricular complexes (PVCs) by 70%, pairs by 80%, runs of 3 to 15 beats by 90%, and all ventricular tachycardia (VT) more than 15 beats by 100%. In this analysis, we examine outcome in subjects meeting two more stringent sets of criteria, (1) reduction of total PVCs by 70%, of pairs by 80%, and of all VT by 100% (new criteria set 1) and (2) reduction of total PVCs by 80%, of pairs by 90%, and of all VT by 100% (new criteria set 2). In electrophysiology (EPS) limb patients, we compared arrhythmia recurrence when efficacy was declared with triple extrastimuli as compared with maximally testing with double extrastimuli, and arrhythmia recurrence was compared in patients tested with identical versus any more aggressive protocol on drug than was used before drug. We also compared the predictive accuracy of zero versus 3 to 15, and 0 to 5, 6 to 10, and more than 10 induced beats on drug. Additionally, we compared predictive accuracy of the HM- and EP-guided limbs excluding patients on beta blockers and those with noncoronary disease. Lastly, to determine whether concordant results on HM and EPS testing would provide more accurate efficacy predictions than EP testing alone, HM recordings obtained in EPS-limb patients but not processed or used during the course of the EVSEM study were analyzed. The original ESVEM HM criteria, new set 1, and new set 2 yielded predicted drug efficacy rates of 77%, 68%, and 58%, respectively; however, arrhythmia recurrence rates were unchanged. Similarly, arrhythmia recurrence rates for patients tested with triple versus less than triple extrastimuli (p=.238), more aggressive versus identical protocols (p=.955), and 0 to 5 v 6 to 10 v more than 10 induced beats (p=.263) or 0 v 3 to 15 induced beats (p=.106) were unchanged. in the 215 (of 286) patients with coronary disease and not receiving beta blockers, there was still no difference in arrhythmia recurrence or mortality between the noninvasive and invasive limbs in ESVEM. Lastly, in patients with drug efficacy predictions by EPS testing, there was no difference in outcome in patients who had concordant versus discordant efficacy prediction by simultaneously obtained HMs. The use of more stringent testing methods and efficacy criteria would not have significantly improved the predictive accuracy of drug assessment by HM or EPS in the ESVEM trial. Additionally, excess noncoronary disease in EP-guided patients and excess beta-blocker used in HM-guided patients did not influence the results in the ESVEM trial.

Cost-effectiveness of implantable defibrillator as first-choice therapy versus electrophysiologically guided, tiered strategy in postinfarct sudden death survivors. A randomized study

BACKGROUND

Rising costs of health care, partly as a result of costly therapeutic innovations, are of concern to both the medical profession and healthcare authorities. The implantable cardioverter-defibrillator (ICD) is still not remunerated by Dutch healthcare insurers. The aim of this study was to evaluate the cost-effectiveness of early implantation of the ICD in postinfarct sudden death survivors.

METHODS AND RESULTS

Sixty consecutive postinfarct survivors of cardiac arrest caused by ventricular tachycardia or fibrillation were randomly assigned either ICD as first choice (n = 29) or a tiered therapy starting with antiarrhythmic drugs and guided by electrophysiological (EP) testing (n = 31). Median follow-up was 729 days (range, 3 to 1675 days). Fifteen patients died, 4 in the early ICD group and 11 in the EP-guided strategy group (P = .07). For quantitative assessment, the cost-effectiveness ratio was calculated for both groups and expressed as median total costs per patient per day alive. Because effectiveness aspects other than mortality are not incorporated in this ratio, other factors related to quality of life were used as qualitative measures of cost-effectiveness. The cost-effectiveness ratios were $63 and $94 for the early ICD and EP-guided strategy groups, respectively, per patient per day alive. This amounts to a net cost-effectiveness of $11,315 per patient per year alive saved by early ICD implantation. Costs in the early ICD group were higher only during the first 3 months of follow-up, but as a result of the high proportion of therapy changes, including arrhythmia surgery and late ICD implantation, costs in the EP-guided strategy group became higher after that. Patients discharged with antiarrhythmic drugs as sole therapy had the lowest total costs. This subset, however, showed extremely high mortality, resulting in a poor cost-effectiveness ratio ($196 per day). Invasive therapies and hospitalization were the major contributors to costs. If quality-of-life measures are taken into account, the cost-effectiveness of early ICD implantation was even more favorable. Recurrent cardiac arrest and cardiac transplantation occurred in the EP-guided strategy group only, whereas exercise tolerance, total hospitalization duration, number of invasive procedures, and antiarrhythmic therapy changes were significantly in favor of early ICD implantation.

CONCLUSIONS

In terms of cost-effectiveness, early ICD implantation is superior to the EP-guided therapeutic strategy in postinfarct sudden death survivors.

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).