Low recurrence of syncope in patients with inducible sustained ventricular tachyarrhythmias treated with an implantable cardioverter-defibrillator

AIMS

To determine the effectiveness of the implantable cardioverter defibrillator (ICD) in preventing recurrence of syncope in patients with structural heart disease, previously unexplained syncope and inducible ventricular arrhythmias.

METHODS

Thirty-eight patients with syncope, structural heart disease and inducible arrhythmias had an ICD implanted. All ICDs delivered antitachycardia pacing and shocks of adjusted energy. Detection and therapy were programmed according to uniform criteria.

RESULTS

The mean age of the patients was 63+/-11 years and most of them were male (36/38). After a mean follow-up of 28+/-15 (4-61) months, six patients died and one underwent heart transplantation. Syncope recurred in three patients, but in none of them was it caused by an arrhythmic event. In 18 patients, 113 episodes of ventricular tachycardia/ventricular fibrillation were detected and appropriately treated by the ICD. The mean time from implant until first appropriate therapy was 18+/-14 months. The actuarial probability of receiving appropriate therapy was 20% and 42% at 12 and 24 months, respectively.

CONCLUSIONS

In patients with unexplained syncope, structural heart disease and inducible arrhythmias, ICD prevents syncope associated with arrhythmic events. Frequent effective use of antitachycardia pacing and shocks of adjusted energy seem essential to this aim.

Sexual activity as a trigger for ventricular tachycardia in a patient with implantable cardioverter defibrillator

Occurrence of life threatening arrhythmias and sudden death during or following sexual activity is infrequent. We describe a patient with an implantable cardioverter defibrillator who developed increased ventricular ectopic activity followed by sustained ventricular tachycardia during extramarital coitus. A review of literature and management is discussed.

Robotically enhanced placement of left ventricular epicardial electrodes during implantation of a biventricular implantable cardioverter defibrillator system

Biventricular pacing has gained increasing acceptance in advanced heart failure patients. One major limitation of this therapy is positioning the left ventricular stimulation lead via the coronary sinus. This report demonstrates the feasibility of totally endoscopic direct placement of an epicardial stimulation lead on the left ventricle using the daVinci surgical system.

Incessant ventricular tachycardia

The case of an 87-year-old woman with a significant history of coronary artery disease illustrates the challenge associated with intractable ventricular tachycardias, and demonstrates the various options available for terminating and controlling the potentially fatal arrhythmia. A favorable outcome was obtained using advanced cardiac life support guidelines, current pharmacological regimens, ventricular burst pacing with overdrive suppression, intra-aortic balloon counterpulsation, coronary revascularization and implantable cardioverter-defibrillator insertion. These modalities, as well as other therapeutic alternatives, are discussed in the management of incessant ventricular tachycardia.

Outcome of women versus men with ventricular tachyarrhythmias treated with the implantable cardioverter defibrillator

INTRODUCTION

Important sex differences in the incidence and outcome of patients with ischemic heart disease, the leading cause of ventricular tachyarrhythmias, have been identified. Implantable cardioverter defibrillator (ICD) therapy has become the treatment of choice for patients with ventricular tachycardia (VT) and ventricular fibrillation (VF), but little is known about gender differences in the outcome of ICD-treated patients.

METHODS AND RESULTS

In this retrospective study, we compared arrhythmic events and survival of 376 women and 1,654 men treated with an ICD as part of prospective evaluations of transvenous devices or lead systems. Women were younger (62+/-14 years vs 65+/-12 years, P = 0.0005), had higher left ventricular ejection fraction (0.36+/-0.15 vs 0.32+/-0.13, P < 0.0001), were more likely to present with VF (34% vs 19%, P < 0.001), and had lower implantation defibrillation threshold (11+/-6 vs 13+/-6 J, P < 0.0001). Implant complication rates were similar in men and women (2.6% vs 3.5%, P = 0.46). The 1-year and 2-year cumulative rates of appropriate ICD therapies were 31.4% and 38.4% for men and 32.6% and 40.8% for women, respectively (P = 0.63). The unadjusted 1-year and 2-year cumulative survival rates were 95.6% and 93.7% for men and 95.7% and 94.3% for women, respectively (P = 0.98). Adjusted total (P = 0.61), sudden (P = 0.82), and cardiac (P = 0.34) death-free survivals also were similar in men and women.

CONCLUSION

Despite clinical differences suggesting women are at lower risk than men, men and women with VT/VF who are treated with an ICD have similar arrhythmic event and survival rates. These factors should be considered when determining risk and prescription of ICD therapy for women.

Catheter ablation for cardiac arrhythmias

The clinical introduction of catheter ablation in 1981 revolutionized the treatment of cardiac arrhythmias. Implementation of radiofrequency as an alternative energy source, with the advantages of higher selectivity and less collateral damage, provided an expansion of catheter ablation therapy. Today the majority of arrhythmias can potentially be cured with catheter ablation therapy. The safety and efficacy of catheter ablation for treatment of AV nodal reentrant tachycardia, accessory pathway arrhythmias, focal atrial tachycardia, atrial flutter and idiopathic ventricular tachycardia, is well established. Catheter ablation for treatment of atrial fibrillation and ventricular tachycardia secondary to structural heart disease, remains an area of active research. In this article we will review the current state of knowledge about the technique, indications, and results of catheter ablation for the treatment of cardiac arrhythmias.

Ventricular tachycardia in congenital adrenal hyperplasia

Severe hyperkalaemia in patients with congenital adrenal hyperplasia in association with aggravating factors such as acidosis and hypocalcaemia can cause life-threatening ventricular arrhythmias. Treatment of the underlying cause may be the only modality required in such cases. We report a 20-day-old male presenting with ventricular tachycardia due to electrolyte abnormalities in salt-losing congenital adrenal hyperplasia. Sudden cardiac deaths reported earlier in such cases thus gain credence.

Nondominant right coronary artery occlusion and ventricular tachyarrythmias

It is usually considered that occlusion of a nondominant right coronary artery is not associated with significant consequences. We report two cases of nondominant right coronary artery occlusion that presented with sudden cardiac death. Timely intervention resulted in complete resolution of the ventricular arrhythmias. This highlights the need for greater vigilance in the recognition and treatment of these lesions.

Indications for implantable cardioverter defibrillator therapy

The implantable cardioverter defibrillator (ICD) is now an integral therapy for cardiac patient care. More than 20 years have passed since the first ICD implant. Sudden cardiac death from arrhythmia (ventricular tachycardia and fibrillation) has been significantly decreased because of the use of ICD therapy. Primary treatment trials have shown ICD therapy to be superior to drug therapy. Most of these trials compared ICD therapy with amiodarone or sotalol. Prevention trials have also been completed. Patients with nonsustained ventricular tachycardia, low left ventricular ejection fraction, and coronary artery disease were evaluated with electrophysiology studies. Patients with inducible ventricular arrhythmias were treated with ICD or drug suppression therapy. ICD therapy was superior to drug therapy for prevention of fatal arrhythmias. Ongoing trials include evaluation of ICD therapy for patients with high-risk substrates: congestive heart failure, dilated cardiomyopathy, hypertrophic cardiomyopathy, and repolarization syndromes. Factors such as medication inefficacy/side effects, transvenous ICD implantation and overwhelming mortality benefits have expanded ICD usage beyond the original restrictive guidelines.

Effectiveness and cost-effectiveness of implantable cardioverter defibrillators in the treatment of ventricular arrhythmias among medicare beneficiaries

PURPOSE

The implantable cardioverter defibrillator has been assessed in randomized trials, but the generalizability of trial results to broader clinical settings is unclear. Our purpose was to evaluate the outcomes and costs of defibrillator use in an unselected population.

SUBJECTS AND METHODS

We identified 125,892 Medicare patients who were discharged between 1987 and 1995 after hospitalization with a primary diagnosis of ventricular tachycardia or ventricular fibrillation, 7789 of whom (6.2%) received a defibrillator. We used a multivariable propensity score that included patient and hospital characteristics to match pairs of patients, in which one patient received a defibrillator and the other did not. We compared mortality and costs in these 7612 matched pairs during 8 years of follow-up.

RESULTS

Patients who received a defibrillator were more likely to be younger, white, male, and urban dwelling, and to have ischemic heart disease, heart failure, or a history of ventricular fibrillation. In the matched-pairs analysis, those who received a defibrillator had significantly lower mortality: 11% versus 19% at 1 year (odds ratio [OR] = 0.57; 95% confidence interval [CI]: 0.51 to 0.63), 20% versus 30% at 2 years (OR = 0.66; 95% CI: 0.60 to 0.72), and 28% versus 39% at 3 years (OR = 0.70; 95% CI: 0.63 to 0.77). These patients also had lower mortality at 8 years (P = 0.0001), although this advantage over patients who received medical treatment only decreased over time. Expenditures among defibrillator recipients were consistently higher, with a cost-effectiveness ratio of $78,400 per life-year gained.

CONCLUSION

The use of implantable defibrillators was associated with significantly lower mortality and higher costs, whereas the cost-effectiveness was higher than many, but not all, generally accepted therapies.

Effect of surgical revascularization in patients with coronary artery disease and ventricular tachycardia or fibrillation in the Antiarrhythmics Versus Implantable Defibrillators (AVID) Registry

BACKGROUND

Patients who undergo resuscitation from near-fatal ventricular arrhythmias often have significant coronary artery disease, and revascularization has been shown to reduce myocardial ischemia and cardiac arrest episodes in this patient population. The magnitude of benefit attributed to revascularization has varied by study, and the use of adjunct implantable cardioverter defibrillator (ICD) therapy has not been well-characterized.

METHODS AND RESULTS

The Antiarrhythmics Versus Implantable Defibrillators (AVID) registry included 3117 patients with life-threatening ventricular arrhythmias, of whom 2321 (77%) had documented coronary artery disease and 281 (17%) underwent a coronary artery bypass grafting revascularization procedure after the index event. Patients who underwent a revascularization procedure were younger, had a lower incidence rate of prior myocardial infarction and ventricular arrhythmia, had a higher left ventricular ejection fraction, had less congestive heart failure, and were more likely to have had ventricular fibrillation as the presenting arrhythmia. Patients who underwent revascularization had a better survival rate than did those who did not undergo such a procedure after the index event, and adjustment for differing baseline patient covariates did not alter the relative survival rate benefit. Further, ICD implantation offered a similar survival rate advantage to those patients in the AVID registry with coronary artery disease independent of revascularization.

CONCLUSION

Coronary revascularization in the AVID registry patients with coronary artery disease effected a survival rate benefit that was not attributable to differences in baseline patient characteristics. The benefit of ICD on patient survival rate was not attenuated by a revascularization procedure.

Efficacy and temporal stability of reduced safety margins for ventricular defibrillation: primary results from the Low Energy Safety Study (LESS)

BACKGROUND

Traditionally, a safety margin of at least 10 J between the maximum output of the pulse generator and the energy needed for ventricular defibrillation has been used because lower safety margins were associated with unacceptably high rates of failed defibrillation and sudden cardiac death. The Low Energy Safety Study (LESS) was a prospective, randomized assessment of the safety margin requirements for modern implantable cardioverter-defibrillator (ICD) systems.

METHODS AND RESULTS

A total of 636 patients undergoing initial ICD implantation with a dual-coil lead and active pulse generator were evaluated. The defibrillation threshold (DFT) and enhanced DFT (DFT+ and DFT++) were measured using a modified step-down protocol. Conversion testing of induced ventricular fibrillation before discharge, at 3 months, and at 12 months was performed, as was randomization to chronic programming at either 2 steps above DFT++ or maximal output. The induced ventricular fibrillation data had conversion success rates of 91.4%, 97.9%, 99.1%, 99.6%, and 99.8% for safety margins of 0, 1, 2, 3, and 4 steps above the DFT++, respectively. A margin of 4 to 6 J was adequate to maintain high conversion success over time (98.9% before discharge versus 99.2% at 12 months; P=NS). Over a mean follow-up of 24+/-13 months, conversion of spontaneously occurring ventricular tachyarrhythmias >200 bpm was identical (97.3%), despite a safety margin difference of 5.2+/-1.1 J for the 2-step group versus 20.8+/-4.2 J for maximal output.

CONCLUSIONS

With a rigorous implantation algorithm, a safety margin of about 5 J is adequate for safe implantation of modern ICD systems.

Cost-effectiveness of the implantable cardioverter-defibrillator versus antiarrhythmic drugs in survivors of serious ventricular tachyarrhythmias: results of the Antiarrhythmics Versus Implantable Defibrillators (AVID) economic analysis substudy

BACKGROUND

The implantable cardioverter-defibrillator (ICD) is an effective but expensive device. We used prospectively collected data from a large randomized clinical trial of secondary prevention of life-threatening ventricular arrhythmias to determine the cost-effectiveness of the ICD compared with antiarrhythmic drug (AAD) therapy, largely with amiodarone.

METHODS AND RESULTS

Charges for initial and repeat hospitalizations, emergency room, and day surgery stays and the costs of antiarrhythmic drugs were collected on 1008 patients. Detailed records of all other medical encounters and expenses were collected on a subgroup of 237 patients. Regression models were then created to attribute these expenses to the rest of the patients. Charges were converted to 1997 costs using standard methods. Costs and life years were discounted at 3% per year. Three-year survival data from the Antiarrhythmics Versus Implantable Defibrillators trail were used to calculate the base-case cost-effectiveness (C/E) ratio. Six-year, twenty-year, and lifetime C/E ratios were also estimated. At 3 years, total costs were $71 421 for a patient taking AADs and $85 522 for a patient using an ICD, and the ICD provided a 0.21-year survival benefit over AAD treatment. The base-case C/E ratio was thus $66 677 per year of life saved by the ICD compared with AAD therapy (95% CI, $30 761 to $154 768). Six- and 20-year C/E ratios remained stable between $68 000 and $80 000 per year of life saved.

CONCLUSIONS

The ICD is moderately cost-effective for secondary prevention of life-threatening ventricular arrhythmias, as judged from prospectively collected data in a randomized clinical trial.

Successful rescue of sustained ventricular tachycardia/ventricular fibrillation after coronary artery bypass grafting by extracorporeal membrane oxygenation

Extracorporeal membrane oxygenation (ECMO) can be set up quickly at the bedside and provides reliable temporary mechanical circulatory support for severe heart failure. We report the case of a 56-year-old female with circulatory collapse due to sustained ventricular tachycardia and ventricular fibrillation (VT/Vf) after coronary artery bypass grafting (CABG) who was successfully resuscitated using ECMO. The sustained VT/Vf might have been secondary to myocardial stunning, ischemia, infarction, or reperfusion. There were 40 cardioversions within the first 5 postoperative days. The patient improved after 8 days of ECMO in addition to use of an intraaortic balloon pump and administration of inotropic agents for profound heart failure. Left ventricular ejection fraction improved from 28% preoperatively to 54.5% on the 20th postoperative day. Cardiogenic shock due to sustained VT/Vf after CABG may be an indication for ECMO support. Immediate establishment of circulatory support using ECMO provides valuable time for spontaneous and interventional correction of reversible causes of sustained VT/Vf.

Prognostic significance of nonsustained ventricular tachycardia after revascularization

INTRODUCTION

Two randomized trials (Multicenter Automatic Defibrillator Implantation Trial [MADIT] and Multicenter Unsustained Tachycardia Trial [MUSTT]) suggest that implantable cardioverter defibrillator (ICD) placement is associated with improved survival in patients with coronary artery disease, depressed left ventricular function, and nonsustained ventricular tachycardia (VT) who also have inducible sustained VT. However, neither study directly addresses the management of such patients who develop nonsustained VT early after revascularization.

METHODS AND RESULTS

We evaluated 109 consecutive patients who underwent electrophysiologic testing to evaluate nonsustained VT, which occurred 5 +/- 4 days following revascularization. Sustained monomorphic VT was inducible in 46 (42%) patients; these patients received an ICD. The remaining 63 (58%) noninducible patients received neither antiarrhythmic drug therapy nor an ICD. During 27 +/- 12 months of follow-up, 15 (33%) of 45 patients with an implanted ICD received at least one appropriate therapy from the device and 26 (24%) of the 109 study patients died. The 1- and 2-year freedom from ventricular tachycardia/fibrillation or sudden death in noninducible patients (97% and 93%) was significantly greater than that of inducible patients (84% and 71%; P = 0.001). However, no difference was observed in total mortality.

CONCLUSION

Patients with nonsustained VT during the early postrevascularization period who have inducible VT have a high incidence of arrhythmic events. Although this study was not designed to assess the impact of ICD placement on the total mortality of inducible patients, the finding that one third of these patients received appropriate ICD therapy suggests that the device may have a protective effect in these patients.

Inadvertent detection of 60-Hz alternating current by an implantable cardioverter defibrillator

A patient with an ICD received therapies from his ICD while exercising in an indoor swimming pool. Interrogation of the ICD revealed inappropriate detection of 60-Hz alternating current artifact and delivery of ICD therapies.

Initial experience with an implantable cardioverter-defibrillator incorporating cardiac resynchronization therapy

OBJECTIVES

The purpose of this study was to evaluate an implantable cardioverter-defibrillator (ICD) incorporating biventricular pacing.

BACKGROUND

Biventricular pacing improves the symptoms of heart failure, a frequent problem in ICD recipients.

METHODS

This prospective multicenter study evaluated the safety and efficacy of an ICD with biventricular pacing.

RESULTS

A total of 84 patients with a standard ICD indication, symptomatic heart failure, left ventricular (LV) ejection fraction <35% and a QRS duration >130 ms were included in the trial. In 81 of 84 patients the LV lead was successfully implanted. Patients significantly improved in the 6-min hall-walk test (baseline 304 plus minus 131 m, three months 397 plus minus 142 m, p < 0.001), quality of life (baseline 38.9 plus minus 21.2, three months 26.5 plus minus 21.2, p < 0.001) and the New York Heart Association (NYHA) classification (baseline 2.8 plus minus 0.6, three months 2.2 plus minus 0.5). Left ventricular end-diastolic (from 79.6 plus minus 13.0 mm to 73.6 plus minus 12.9 mm, p = 0.002) and end-systolic (from 68.3 plus minus 13.5 mm to 63.9 plus minus 12.9 mm, p < 0.001) diameter decreased, and fractional shortening increased (from 16 plus minus 6% to 18 plus minus 6%, p = 0.018). Of the patients 26 experienced 472 episodes of spontaneous sustained ventricular tachyarrhythmias. All episodes were successfully terminated except for 16 episodes occurring in a patient with incessant ventricular tachycardia. Biventricular antitachycardia pacing was more effective than right ventricular antitachycardia pacing (p < 0.001). During follow-up (median 185 days, range 12 to 344 days) five patients died from progressive heart failure.

CONCLUSIONS

Incorporating biventricular pacing in an ICD is feasible and leads to an improvement of heart failure symptoms. Therefore, this therapy may become an option for patients who need ICD therapy in the presence of severe heart failure.

Implantable defibrillator event rates in patients with idiopathic dilated cardiomyopathy, nonsustained ventricular tachycardia on Holter and a left ventricular ejection fraction below 30%

OBJECTIVES

This study investigated the incidence of appropriate implantable cardioverter defibrillator (ICD) interventions for ventricular tachycardia (VT) or ventricular fibrillation (VF) in patients with idiopathic dilated cardiomyopathy (IDC) and nonsustained VT in the presence of a left ventricular ejection fraction below 30%, versus in patients with syncope and patients with a history of VT or VF.

BACKGROUND

To date, only limited information is available about the prophylactic use of ICDs in patients with IDC.

METHODS

From January 1993 to July 2000, 101 patients with IDC underwent implantation of ICDs with electrogram storage capability at our institution. Patients were placed into one of three groups according to their clinical presentation: asymptomatic or mildly symptomatic nonsustained VT in the presence of a left ventricular ejection fraction < or = 30% (49 patients, prophylactic group), unexplained syncope or near syncope (26 patients, syncope group) and a history of sustained VT or VF (26 patients, VT/VF group).

RESULTS

During 36 +/- 22 months follow-up, 18 of 49 patients (37%) in the prophylactic group received appropriate shocks for VT or VF, compared with 8 of 26 patients (31%) in the syncope group and with 9 of 26 patients (35%) of the VT/VF group. Multivariate Cox analysis of baseline clinical variables identified left ventricular ejection fraction, atrial fibrillation and a history of sustained VT or VF as predictors for appropriate ICD interventions during follow-up.

CONCLUSIONS

Patients with IDC and prophylactic ICD implantation for nonsustained VT in the presence of a left ventricular ejection fraction < or = 30% had an incidence of appropriate ICD interventions similar to that of patients with a history of syncope or sustained VT or VF. These findings indicate that ICDs may have a role in not only secondary but also primary prevention of sudden death in IDC.