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PubMed1994

Nonthoracotomy- versus thoracotomy-implantable defibrillators. Intention-to-treat comparison of clinical outcomes.

BACKGROUND: Nonthoracotomy-implantable cardioverter/defibrillator (ICD) systems may represent a significant advance in the treatment of patients with life-threatening ventricular arrhythmias, but their merits relative to those of the well-established thoracotomy systems remain largely unknown. The objective of this study was to compare the short- and long-term clinical outcomes after attempted ICD implantation via a nonthoracotomy versus thoracotomy approach in similar groups of patients. METHODS AND RESULTS: Between September 1990 and December 1992, 212 consecutive patients underwent attempted ICD system implantation without concomitant cardiac surgery at a single institution. Approach selection was not randomized but rather was based primarily on hardware availability. Primary comparisons of short- and long-term outcome were performed according to the "intention-to-treat" principle. Implantation was attempted via a nonthoracotomy approach in 120 patients (57%) and via a thoracotomy approach in 92 patients (43%). Prior cardiac surgery was more prevalent in the nonthoracotomy patients; otherwise, groups did not differ significantly in terms of prognostically relevant clinical characteristics. Nonthoracotomy implantation was successful in 101 patients (84%). After crossover to thoracotomy implantation (14 patients), the eventual success rate for ICD system implantation was 96% in the nonthoracotomy group. Thoracotomy implantation was successful in 89 patients (97%). Operative mortality was 3.3% in the nonthoracotomy and 4.3% in the thoracotomy groups (P = .73). Nonthoracotomy group patients were less likely to experience postoperative congestive heart failure (6% versus 16%; P = .02) or supraventricular arrhythmia (6% versus 18%; P = .004) and had significantly shorter postoperative intensive care and total hospitalization. Total hospital costs were significantly lower in the nonthoracotomy group ($32,205 versus $37,265; P = .001). After a follow-up of 16 +/- 9 months, there were 17 deaths in the nonthoracotomy group (none sudden) and 12 deaths in the thoracotomy group (1 sudden). One- and 2-year Kaplan-Meier survival probabilities were .87 (95% CI, .78 to .91) and .80 (95% CI, .68 to .88) in the nonthoracotomy group and .90 (95% CI, .82 to .95) and .87 (95% CI, .77 to .93) in the thoracotomy group (P = .56; log-rank test). CONCLUSIONS: Nonthoracotomy ICD implantation is associated with reduced surgical morbidity, postoperative hospital care requirement, and hospital costs and has similar efficacy in preventing sudden death relative to the thoracotomy approach. From these nonrandomized data, it appears that a nonthoracotomy approach should be considered preferable in most patients requiring ICD therapy.

Aged↗
PubMed1996

The implantable cardioverter defibrillator: modern implantation techniques and their impact on outcomes.

The implantable cardioverter defibrillator has revolutionized the management of lethal ventricular arrhythmias in susceptible patients. In its second decade of existence, the implantable cardioverter defibrillator has undergone significant technologic enhancements which have resulted in ease of implantation, lower mortality rates, and shorter hospital stays. The newer pectoral size devices have been successfully implanted in a variety of patients, using models from several device manufacturers. Improvements in lead technology have paralleled those of the device itself. These include the unique concept of "unipolar" defibrillation as well as the trend toward dual chamber lead systems. Results of these newer technologies are favorable: comparably low defibrillation thresholds have been reported with the newer lead configurations, with lower operative mortality. However, morbidity attached to earlier lead systems remains as high as 16%. It is anticipated that the results will further improve as shorter transvenous leads and better connector material become routinely available. Finally, the clinical outcomes in the early postoperative phase indicate fewer proarrhythmic effects leading to shorter hospital stays in patient equipped with the latest types of pectoral implants. Continued progress at the level of the patient-device interface is expected to result in every better patient acceptance and proliferation of implantable cardioverter defibrillator therapy.

Arrhythmias, Cardiac↗
PubMed2003

Effectiveness of implantable defibrillators for preventing arrhythmic events and death: a meta-analysis.

OBJECTIVES: The aim of this study was to compare the effectiveness of the implantable cardioverter defibrillator (ICD) and medical strategies for prevention of arrhythmic events and death. BACKGROUND: The ICD is a potential strategy to reduce mortality in patients at risk of sudden death. METHODS: The MEDLINE, EMBASE, and Cochrane Library electronic databases were searched from January 1966 to April 2002. All published randomized controlled trials comparing ICD implantation with medical therapy were reviewed. Four independent reviewers extracted data on all-cause mortality, nonarrhythmic death, and arrhythmic death using a standardized protocol. RESULTS: Nine studies including over 5,000 patients were synthesized using both fixed-effects and random-effects models. The primary and secondary prevention trials showed a significant benefit of the ICD with respect to arrhythmic death, with relative risks (RR) of 0.34 and 0.50, respectively (both p < 0.001). The mortality benefit of the ICD was entirely attributable to a reduction in arrhythmic death (all trials: p < 0.00001). Whereas the secondary prevention trials exhibited a robust decrease in all-cause ICD mortality (RR 0.75; p < 0.001), the pooled primary prevention trials demonstrated decreased all-cause ICD mortality (RR 0.66; p < 0.05) which was dependent on selected individual trials. The disparity in ICD-related mortality reductions in the primary prevention trials was related to variability in the incidence of arrhythmic death between individual studies. CONCLUSIONS: Although the ICD decreases the risk of arrhythmic death, its impact on all-cause mortality is related to the underlying risk of arrhythmia-related death relative to competing causes. Given the cost of the device strategy, policies of targeted intervention based on the future risk of arrhythmia are warranted.

Arrhythmias, Cardiac↗
PubMed2004

Increased incidence of life-threatening ventricular arrhythmias in implantable defibrillator patients after the World Trade Center attack.

OBJECTIVES: This study was designed to evaluate whether the destruction of the World Trade Center (WTC) on September 11, 2001 (9/11), led to an increased frequency of ventricular arrhythmias among patients fitted with an implantable cardioverter-defibrillator (ICD). BACKGROUND: The WTC attack induced psychological distress. Because ICDs store all serious arrhythmias for months, the attack provided a unique opportunity to compare pre- and post-9/11 frequencies of potentially lethal arrhythmias among ICD patients. METHODS: Two hundred consecutive ICD patients who presented for regularly scheduled follow-up to six affiliated clinics were recruited into this observational study. The electrograms stored in the ICDs for the three months before 9/11 and 13 months thereafter were scrutinized in a blinded manner (relative to date) for all ventricular tachyarrhythmias (tachycardia or fibrillation) triggering ICD therapy. RESULTS: The frequency of tachyarrhythmias increased significantly for the 30 days post-9/11 (p = 0.004) relative to all other months between May 2001 and October 2002. In the 30 days post-9/11, 16 patients (8%) demonstrated tachyarrhythmias, compared with only seven (3.5%) in the preceding 30 days, representing a 2.3-fold increase in risk (95% confidence interval 1.1 to 4.9; p = 0.03). The first arrhythmic event did not occur for three days following 9/11, with events accumulating in a progressive non-clustered pattern. CONCLUSIONS: Ventricular arrhythmias increased by more than twofold among ICD patients following the WTC attack. The delay in onset and the non-clustered pattern of these events differ sharply from effects following other disasters, suggesting that subacute stress may have served to promote this arrhythmogenesis.

Aged↗
PubMed2006

Impact of implantable defibrillators and resynchronization therapy on outcome in patients with left ventricular dysfunction--a meta-analysis.

BACKGROUND: The clinical benefits of cardiac resynchronization therapy (CRT) and primary prophylactic implantable cardioverter defibrillator (ICD) in patients with left ventricular systolic dysfunction (LVSD) are debated. OBJECTIVE: To evaluate by a meta-analysis the effect of CRT and prophylactic ICD therapy in patients with LVSD. METHODS: Eligible trials evaluating the effect of CRT vs. no-CRT, ICD vs. no-ICD and adding ICD to CRT vs. no-ICD were selected and meta-analyzed. The outcomes were: all cause mortality, cardiac mortality, hospitalization for heart failure and change in exercise tolerance and New York Heart Association class. RESULTS: Implantation of CRT reduced all cause mortality odds ratio (OR) = 0.73 (0.60-0.89) p = 0.002 and hospitalization for heart failure OR = 0.60 (0.45, 0.80) p = 0.001, increased peak oxygen consumption by 1.77 (0.32-3.22) ml/kg/min p = 0.017 and improved New York Heart Association class by at least one class with OR = 1.52 (1.30, 1.77) p < 0.0001. Implantation of ICD reduced all-cause mortality OR = 0.75 (0.59-0.96) p = 0.025 and cardiac mortality OR = 0.63 (0.48, 0.82) p = 0.001. Adding ICD to CRT reduced all cause mortality OR = 0.69 (0.53-0.91) p = 0.008. CONCLUSION: Selective patients with LVSD benefit from CRT, ICD or both. Further investigations are necessary to clarify which patients benefit most from a single or combined device implantation.

Defibrillators, Implantable↗
PubMedDate not supplied

[Implantable defibrillators. Sudden death: high risk].

INCIDENCE: The incidence of sudden death remains high. The basic causes are related to ischemic heart disease and heart failure. Automatic defibrillation is the best treatment, as first conceived and implanted by Mirovski twenty years ago. MARKERS OF RISK OF SUDDEN DEATH: Left ventricular dysfunction, functional class and spontaneous and induced ventricular hyperexcitability identify a high-risk population. THERAPEUTIC APPROACH: Drug treatments used in the post infarction period or for heart failure (beta-blockers, converting enzyme inhibitors and amiodarone) have demonstrated a certain efficacy in preventing sudden death. However, different therapeutic trials comparing the efficacy of defibrillators and drug treatments have demonstrated the 20 to 46% superiority of defibrillation in terms of reduced mortality.

Cause of Death↗
PubMed1990

Operative risks of the implantable defibrillator versus endocardial resection.

Both map-guided endocardial resection (ER) and the automatic implantable cardioverter defibrillator (AICD) are currently used for surgical treatment of patients who have sustained ventricular tachyarrhythmias. Some authors have preferred AICD implant due to a lower published operative mortality rate. To determine if there is a discrepancy in mortality rates between the two techniques, we analyzed hospital survival in 46 patients undergoing ER and in 44 patients undergoing AICD implantation during the same 3-year period. Two ER patients (4%) died before hospital discharge. Two patients (4%) died after AICD implantation. At predischarge electrophysiologic study five patients (11%) had inducible ventricular tachycardia and received antiarrhythmic drug therapy after ER. In contrast 35 of 42 patients surviving AICD placement received chronic long-term antiarrhythmic therapy (p less than 0.05 compared to ER). Our experience shows that ER and AICD placement may be carried out with similar procedure-related mortality and morbidity rates. Lower operative risks should not be a reason for choosing the AICD over ER for surgical treatment of ventricular tachyarrhythmias. The AICD may actually improve the results of ER by offering an alternative to ventriculotomy in poor-risk surgical candidates.

Aged↗
PubMed2001

Psychological reactions among family members of patients with implantable defibrillators.

OBJECTIVE: To describe psychological reactions among family members of patients receiving an implantable cardioverter/defibrillator (ICD) during the first 9 months after implantation. METHODS: Eighty-two family members (age 56+/-12 years, 74 percent female, 79 percent married, 88 percent Caucasian) of ICD patients completed questionnaires regarding their mood (Profile of Mood State), cognitive illness appraisals (Meaning of Illness Questionnaire) and coping strategies (Jalowiec Coping Scale) prior to ICD implantation, and as well as 1 and 9 months postoperatively. RESULTS: Total mood disturbance score (TMD), threat appraisal, and emotion- and problem-focused coping were highest prior to ICD implantation, and decreased during the first postoperative month showing stable values thereafter. There was no change in challenge appraisal. Multiple regression analysis found that the use of psychotropic drugs (anxiolytics, sedatives; Beta = .25), emotion-focused coping (Beta = .37), and challenge appraisal (Beta =-.21) at 1 month accounted for 26 percent of variance in TMD at 9 mon ths. CONCLUSION: A spouse's ICD implantation is a major stressful event for family members leading to a diminished mood state prior ICD implantation. Reduction in emotion-focused coping and the use of challenge appraisal may improve mood state in family members of ICD patients during early follow-up.

Adaptation, Psychological↗
PubMed2005

Sudden cardiac death unresponsive to implantable defibrillator therapy: an urgent target for clinicians, industry and government.

A major expansion in utilization of implantable cardioverter-defibrillators (ICDs) is anticipated based on the results of randomized clinical trials (RCT) that demonstrate increased survival in a sizable population of patients with reduced left ventricular function. However, if RCT accurately reflect clinical practice, then a substantial proportion of patients will die suddenly despite ICD implantation. ICD-unresponsive sudden cardiac death (SCD) has been recognized since the initial ICD experience. Yet, despite 25 years of technical advances, the frequency of ICD-unresponsive SCD has not declined. Pooled analysis of RCT indicates a crude rate of ICD-unresponsive SCD of 5%. This may not cause alarm in an average practice, but it comprises about 30% of cardiac deaths. Meta-analyses of RCT show that ICD therapy is associated with a relative risk reduction of SCD of approximately 60%, far less than the greater than 90% efficacy that many expect. The suboptimal performance of ICD therapy accounts for the failure of some RCT to achieve statistically significant effects on survival. The number of patients with ICD-unresponsive SCD is highly correlated with the number of cardiac deaths among control patients as well as ICD recipients. Otherwise, no definite patterns have emerged that clearly distinguish this mode of demise from other modes of cardiac death. Retrospective post-hoc analyses have not revealed distinguishing characteristics of patients with ICD-unresponsive SCD with respect to clinical variables, pre-terminal symptoms or to the setting of the terminal event. Despite advanced storage capabilities of implanted devices, almost no information has become available from RCT regarding the terminal rhythm or the response of the ICD. These observations have implications for clinical management and research. Candidates for ICD implantation based on RCT should be accurately informed about the residual risk of SCD. Investigators seeking to identify populations likely to benefit from ICD therapy based on SCD incidence should recognize that a significant fraction may not respond to ICD therapy. Reducing the incidence of ICD-unresponsive SCD would substantially improve survival and cost-effectiveness related to ICD therapy. Close cooperation between clinicians, investigators and representatives of industry and government is urgently needed to develop strategies to identify patients prone to ICD-unresponsive SCD, to determine its mechanisms and to develop methods of prevention and treatment.

Death, Sudden, Cardiac↗
PubMed2002

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.

Adolescent↗
PubMed2001

[Variables of arrhythmia risk in relation to pacemaker and implantable defibrillator].

Patients suffering from heart failure are at high risk of arrhythmic death. Conventional pacemakers have not shown to affect mortality in patients with chronic heart failure and sick sinus syndrome, while this issue is established in patients with III degree or advanced atrioventricular block. Biventricular pacing has recently been introduced in clinical practice and the experience is limited; to date, only an improvement in symptoms and quality of life has been shown. Biventricular pacing with implantable cardioverter-defibrillator back-up is promising. The implantable cardioverter-defibrillator is able to reduce total and sudden mortality in high risk patients, as clearly demonstrated by several randomized clinical trials.

Anti-Arrhythmia Agents↗
PubMed2000

High dispersion of ventricular repolarization after an implantable defibrillator shock predicts induction of ventricular fibrillation as well as unsuccessful defibrillation.

OBJECTIVES: To test the hypothesis that post-shock dispersion of repolarization (PSDR) is higher in T wave shocks that induce ventricular fibrillation (VF) than in those that do not, as well as in implantable cardioverter defibrillator (ICD) defibrillation shocks which fail to terminate VF when compared with those that are successful. BACKGROUND: Ventricular fibrillation has been linked to the presence of dispersion of repolarization, which facilitates reentry. Most of the studies have been done in animals, and the mechanism underlying the generation and termination of VF in humans is speculative and remains to be determined. METHODS: Monophasic action potentials (MAPs) were recorded simultaneously from the right ventricular outflow tract (RVOT) and the right ventricular apex (RVA) in 27 patients who underwent implantation and testing of an ICD. T wave shocks were used to induce VF while the termination was attempted using internal defibrillator shocks. The post-shock repolarization time (PSRT) was measured in both the RVA and RVOT MAPs, and the difference between the two recordings was defined as the PSDR. The averages of PSDR were compared between the successful and unsuccessful inductions and terminations of VF. RESULTS: T wave shocks that induced VF generated a greater PSDR (93.4 +/- 85.1 ms) than the unsuccessful ones (45.1 +/- 55.9 ms, p < 0.001). On the other hand, shocks that failed to terminate VF were associated with a greater PSDR (59.9 +/- 41.2 ms) than shocks that terminated VF (21.1 +/- 20.1 ms), p < 0.001. CONCLUSIONS: A high PSDR following a T wave shock is associated with induction of VF; while following a defibrillating shock, it is associated with its failure and the continuation of VF. Conversely, a low PSDR is associated with failure of a T wave shock to induce VF and successful termination of VF by a defibrillating shock.

Action Potentials↗
PubMed1993

Changing trends in therapy delivery with a third generation noncommitted implantable defibrillator: results of a large single center clinical trial.

Thirty-four patients underwent implantation of a third generation ICD, the 4210 ATP, for sudden cardiac death or ventricular tachycardia. This device incorporates significant telemetry logs as well as a detailed analysis of each arrhythmia episode detected. During the period of clinical follow-up, a mean of 12.2 months, a total of 26,569 VT or VF detections were made. The vast majority of these were either due to atrial fibrillation, nonsustained VT, or "noise" detection, and only 6% led to device therapy. ATP was successful in 86.3% of episodes, with 3.5% accelerations and 2.4% failure of ATP trains. The majority of inappropriate therapy episodes were clustered in seven patients, and all were easily diagnosed with the aid of the extensive telemetry logs and sense histories. Of five late deaths, three were from congestive heart failure, one from cerebrovascular accident, and one unknown. These data reveal that this "tiered" therapy noncommitted ICD performs to expectations; the stored data is of significant value in diagnosing the cause of ICD therapy. In addition, ATP is an effective modality for termination of VT.

Aged↗
PubMed2004

The 1+1 trial: a prospective trial of a dual- versus a single-chamber implantable defibrillator in patients with slow ventricular tachycardias.

BACKGROUND: The tachycardia detection interval (TDI) in implantable cardioverter/defibrillators (ICDs) is conventionally programmed according to the slowest documented ventricular tachycardia (VT), with a safety margin of 30 to 60 ms. With this margin, VTs above the TDI may occur. However, longer TDIs are associated with an increased risk of inappropriate therapy. We hypothesized that patients with slow VTs (<200 bpm) may benefit from a long TDI and a dual-chamber detection algorithm compared with a conventionally programmed single-chamber ICD. METHODS AND RESULTS: Patients with VTs <200 bpm were implanted with a dual-chamber ICD that was randomly programmed to a dual-chamber algorithm and a TDI of > or =469 ms or to a single-chamber algorithm with a TDI 30 to 60 ms above the slowest documented VT cycle length and the enhancement criteria of cycle length variation and acceleration. The primary combined end point was the number of all inappropriate therapies, VTs above the TDI, and VTs with significant therapy delay (>2 minutes). After 6 months, a crossover analysis was performed. Total follow-up was 1 year. One hundred two patients were included in the study. The programmed TDI was 500+/-36 ms during the dual-chamber phase and 424+/-63 ms during the single-chamber phase. For the primary end point (inappropriate therapies, VTs above the TDI, or VTs with detection delay), a moderate superiority of the dual-chamber mode was found: Mann-Whitney estimator=0.6661; 95% CI, 0.5565 to 0.7758; P=0.0040. CONCLUSIONS: Dual-chamber detection with a longer TDI improves VT detection and does not increase the rate of inappropriate therapies despite a considerable increase in tachycardia burden.

Algorithms↗