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PubMed1998

Estimating the proportion of post-myocardial infarction patients who may benefit from prophylactic implantable defibrillator placement from analysis of the CAST registry. Cardiac Arrhythmia Suppression Trial.

We defined the proportion of post-myocardial infarction patients who would have been eligible for the Multicenter Automatic Defibrillator Implantation Trial (MADIT) from a population of 94,797 patients with myocardial infarction entered into the Cardiac Arrhythmia Suppression Trial Registry. From this large population, only between 0.3% to 1.7% would have met strict eligibility criteria for MADIT.

Adult↗
PubMed2001

Ventricular fibrillation sensing and detection by implantable defibrillators: is one better than the others? A prospective, comparative study.

INTRODUCTION: We prospectively compared the performance of the sensing and detection systems of three leading defibrillator manufacturers: Medtronic, Guidant, and Ventritex. METHODS AND RESULTS: Ventricular fibrillation signal was digitally recorded during defibrillator implantation and subsequently played back sequentially to a Medtronic Micro Jewel II 7223Cx, a Guidant MINI II 1762, and a Ventritex Cadet V-115C. The devices were programmed for single-zone detection, at nominal settings. Rate cutoff was set at 320 msec (185/min for the MINI). We analyzed 253 episodes from 47 patients. Median undersensing was 0%, 2.1%, and 5.3% for the Jewel, MINI, and Cadet, respectively (P < 0.001 for each paired comparison). Detection time was 4.1 +/- 1.6 seconds, 3.4 +/- 1.6 seconds, and 4.3 +/- 2.2 seconds for the Jewel, MINI, and Cadet, respectively (P < 0.001 between MINI-Jewel and MINI-Cadet; P < 0.01 between Jewel-Cadet). Delayed detection (detection time longer than the mean of all observations + 2 SD) occurred in 3 (1.2%), 7 (2.8%), and 18 (7.1%) episodes for the Jewel, MINI, and Cadet, respectively. Performance for all devices was worse when the short-separation integrated bipolar lead was used and when the episode followed a failed high-energy shock. CONCLUSION: Statistically significant differences were seen in sensing and detection performance among the devices and device/lead combinations during ventricular fibrillation. These differences are related to specific features of the respective devices and should be taken into account during clinical practice, as well as in future device development.

Adult↗
PubMed1997

Comparison of three different automatic defibrillator implantation approaches: pectoral implantation using conscious sedation reduces procedure times and cost.

Recent technological advances in implantable defibrillator systems (ICD) have changed implantation approaches. The aim of this study was to investigate the influence of these improvements on procedure times, implant-related charges, patient recovery, and morbidity. Ninety-six consecutive patients undergoing implantation of a nonthoracotomy ICD were studied. Implantation was performed under general anesthesia with the generator placed abdominally in 22 patients (group I) and pectorally in 40 patients (group II). Thirty-four patients underwent pectoral implantation using conscious sedation (group III). Groups were comparable with respect to clinical variables. Implantation duration and total procedure duration were shorter in group III (67 +/- 21 minutes and 117 +/- 30 minutes) when compared with group I (100 +/- 25 minutes and 157 +/- 39 minutes) and group II (86 +/- 24 minutes and 153 +/- 34 minutes, P < 0.05). Patients in group III did not require admission to the Post-Anesthesia Care Unit. In contrast, patients in groups I and II spent 92 +/- 28 minutes and 91 +/- 31 minutes in the Post-Anesthesia Care Unit. Implantation-related charges were reduced in patients having pectoral implantation using conscious sedation ($1451 +/- 217 vs. $2354 +/- 550 and $2796 +/- 384, P < 0.05). Patients in group III had a lower frequency of postoperative oral analgesic use (3.2 +/- 2.7 doses, P < 0.05) and a shortened post-operative length of stay (1.9 +/- 1.6 days, P < 0.05) when compared with groups I (5.7 +/- 4.0 doses and 3.3 +/- 1.4 days) and II (5.2 +/- 3.5 doses and 2.6 +/- 1.1 days). The overall complication rate was low (6.3%), with no differences between groups. Advances in ICD technology have simplified implantation, leading to shorter, less painful, and less expensive procedures.

Abdomen↗
PubMed1997

Comparison of clinical characteristics and frequency of implantable defibrillator use between randomized patients in the Antiarrhythmics Vs Implantable Defibrillators (AVID) trial and nonrandomized registry patients.

In the Antiarrhythmics Vs Implantable Defibrillators (AVID) trial, all patients who meet the study entry criteria are followed in a registry. During the period between June 1993 and June 1995, of 1,117 patients who were enrolled in the registry and met the study entry criteria, 476 were randomized to receive either implantable cardioverter-defibrillators (ICDs) or drug therapy (amiodarone or sotalol), and 641 patients were not randomized for a variety of reasons including: patient refusal (42%); physician refusal (43%); concerns about ability to maintain follow-up over several years (10%), and others (6%). There were no significant differences between the 476 randomized and 641 nonrandomized patients with regard to clinical characteristics, left ventricular function, history of congestive heart failure, medical history, and previous cardiac procedures performed before the index event, except that randomized patients were slightly older (65 vs 62 years) and had a slightly higher prevalence of coronary artery disease and previous myocardial infarction. The index event and location of the index event were not significantly different between the 2 groups. Although 14% of registry patients received neither ICD nor antiarrhythmic drug therapy, ICDs were no more frequently used in the registry patient than antiarrhythmic drugs (45% for ICD vs 42% for drugs). Thus, randomized AVID patients have very similar clinical characteristics, cardiac history, and presenting arrhythmias as to nonrandomized eligible patients. Therefore, the results of the AVID trial may be generalized for all patients with AVID-eligible arrhythmias.

Adolescent↗
PubMed1998

Clinical presentation and analysis of risk factors for infectious complications of implantable cardioverter-defibrillator implantations at a university medical center.

The objective of this report is to describe the characteristics of patients who develop infections associated with implantable cardioverter-defibrillators (ICDs) implanted with sternotomy and thoracotomy approaches. A retrospective chart review identified all patients who underwent ICD implantation at a university medical center from November 1982 through February 1990. Several patient and procedural variables were compared between infected patients and noninfected patients. One hundred fifty-seven patients underwent 202 ICD generator implantations (45 generator changes), and nine of these patients developed infection (4.5% per implantation and 5.7% per patient). Of the patient variables analyzed, a significant correlation (P < .0001) was made only with a diagnosis of diabetes mellitus: 36% of diabetics versus 3.9% of nondiabetics were infected. The only patient- or procedure-specific variable that was found to correlate with the development of infection was the presence of diabetes mellitus.

Aged↗
PubMed2006

Causes and consequences of heart failure after prophylactic implantation of a defibrillator in the multicenter automatic defibrillator implantation trial II.

BACKGROUND: Implantable cardioverter-defibrillator (ICD) therapy may be associated with an increased risk for heart failure (HF). The present study evaluated the frequency, causes, and consequences of HF after ICD implantation. METHODS AND RESULTS: We performed a retrospective analysis of the clinical factors and outcomes associated with postenrollment HF events in 1218 patients enrolled in the Multicenter Automatic Defibrillator Implantation Trial II. The adjusted hazard ratios (HRs) of ICD:conventional therapy for first and recurrent HF events were 1.39 (P=0.02) and 1.58 (P<0.001), respectively. The risk was increased among patients who received single-chamber or dual-chamber ICDs. Development of HF was associated with an increased mortality risk (HR, 3.80; P<0.001). Among patients who received a single-chamber ICD, there was a similar survival benefit before and after the development of HF (HR, 0.59 and 0.61, respectively; P=0.92 for difference), whereas among patients with dual-chamber devices, there was a significant reduction in survival benefit after HF (HR, 0.26 and 0.83, respectively; P=0.01 for difference). Within the defibrillator arm of the trial, patients who received life-prolonging therapy from the ICD had an increased risk for first and recurrent HF events (HR, 1.90; P=0.01 and 1.74; P<0.001, respectively). CONCLUSIONS: Patients with chronic ischemic heart disease who are treated with either single-chamber or dual-chamber ICDs have improved survival but an increased risk of HF. The present data suggest that ICD therapy transforms sudden death risk to a subsequent HF risk. These findings should direct more attention to the prevention of HF in patients who receive an ICD.

Adrenergic beta-Antagonists↗
PubMed2002

Efficacy of antitachycardia pacing confirmed by stored electrograms. A retrospective analysis of 613 stored electrograms in implantable defibrillators.

The implantable defibrillator (ICD) is an established therapy in the prevention of sudden cardiac death by defibrillation of ventricular fibrillation. Another specific feature of the ICDs is antitachycardia pacing (ATP) of ventricular tachycardia. Several studies report success rates of ATP in 83 to 98% of cases. In clinical practice the success of terminating ventricular tachycardia is estimated only by automatic device analysis. Therefore the objective of this study was to confirm the efficacy of ATP based on the evaluation of stored electrograms. From the German Ventritex MD-register stored electrograms of 613 monomorphic ventricular tachycardias in 44 patients were analyzed retrospectively. The cycle length of the ventricular tachycardias was between 265 and 560 ms. The success rate of ATP-induced termination of the episodes reached 89.3%; another 2.3% of the ventricular tachycardias were accelerated by antitachycardia pacing into ventricular fibrillation. Left ventricular function did not influence the success rate, but the success rate was lower for fast ventricular tachycardias > 200/min (63.9%). For ventricular tachycardias < 150 bpm there was no restriction of ATP effectiveness. Of the episodes 72.9% were terminated by the first ATP burst. In these cases the duration of tachycardia was very short (11.9 +/- 2.8 s). Fifty-eight ventricular tachycardias (9.5%) had to be terminated by means of a shock, and only one case required 2 shocks. In patients with more than 10 episodes an individual therapy success > 90% was recorded for 80% of them. The very high success rate of the first ATP attempt in ICD therapy can be achieved with uniform programming, and is confirmed for ventricular tachycardias analyzed on the basis of stored electrograms.

Aged↗
PubMed1999

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.

Anti-Arrhythmia Agents↗
PubMed2002

Experience with a dual chamber implantable defibrillator.

An implantable defibrillator with dual chamber pacing may have advantages for pacing, sensing, and detection of brady- and tachyarrhythmias. This study evaluates the safety and performance of a dual chamber implantable cardioverter defibrillator that incorporates an algorithm to discriminate supraventricular from ventricular arrhythmias. The 300 patients in this study had the device implanted for the following indications: ventricular tachycardia (47%), sudden cardiac death survivorship (51%), and prophylactic implants (2%). Patients received dual chamber pacing for accepted bradyarrhythmic (51.7%) or investigational indications. During a mean follow-up period of 1.7 months a total of 1,092 arrhythmia episodes in 96 patients were fully documented in the device memory: 66 patients experienced a total of 796 ventricular tachyarrhythmia episodes and 42 experienced a total of 296 supraventricular episodes. The device appropriately detected 100% of sustained ventricular tachyarrhythmias while reducing the inappropriate detection of supraventricular tachyarrhythmias by 72% compared to single chamber rate only detection. The positive predictive value was 90.5% for ventricular tachyarrhythmia detection in episodes that exceeded the tachycardia detection rate. Adverse events observed in at least 2% of the patients were incisional pain (22%), inappropriate ventricular detection (7%), atrial lead dislodgement (4%), atrial oversensing/undersensing (3%), hematoma (3%), incessant ventricular tachyarrhythmia (2%), and pneumothorax (2%). There were 13 deaths, none of which were attributed to device failure. The Gem DR is safe and effective for the detection and treatment of ventricular tachyarrhythmias. The dual chamber detection algorithm appropriately recognized supraventricular tachycardia with rapid ventricular rates 72% of the time while maintaining 100% detection of sustained ventricular tachyarrhythmias.

Adolescent↗
PubMed1991

Ventricular pacing threshold and time to capture postdefibrillation in patients undergoing implantable cardioverter-defibrillator implantation.

To assess the effect of defibrillation and amiodarone on ventricular pacing threshold and time to capture in patients undergoing automatic implantable cardioverter-defibrillator (AICD) implantation, 28 patients were prospectively evaluated. The patients were entered into one of two protocols: Ia--epicardial ventricular pacing threshold measured at baseline (preventricular fibrillation induction) and 10 and 60 seconds postdefibrillation with 20 J, or Ib--two fibrillation-defibrillation sequences were performed 3 minutes apart and ventricular pacing thresholds were measured for each sequence at baseline and at 10 and 60 seconds postdefibrillation with 20 J. Ten patients also underwent asynchronous pacing at 1.1 times baseline threshold during ventricular fibrillation with measurement of time to capture postdefibrillation. All patients were randomly assigned to receive either amiodarone or no antiarrhythmic drug therapy. Ventricular fibrillation was induced with AC (applied for 1-2 seconds), and standard epicardial bipolar and epicardial patch electrodes of the AICD were used for pacing and defibrillation, respectively. Ventricular pacing threshold at baseline, 10 seconds, 60 seconds, and 3 minutes postdefibrillation did not differ significantly. There were no significant differences in patients with or without amiodarone therapy. Furthermore, there was no transient loss of ventricular capture postdefibrillation or significant difference in time to capture with amiodarone (less than or equal to 2 seconds). We conclude that following internal defibrillation with 20 J: (1) ventricular pacing threshold at 10 seconds, 60 seconds, and 3 minutes were not significantly different from baseline with one or two fibrillation-defibrillation sequences, (2) time to capture was short, and (3) there was no significant difference in no drug versus amiodarone. These findings have direct clinical importance in considering device therapy with both pacing and defibrillating capabilities.

Amiodarone↗
PubMed2004

[Prevalence and clinical course of patients in Spain with acute myocardial infarction and severely depressed ejection fraction who meet the criteria for automatic defibrillator implantation].

The Multicenter Automatic Defibrillator Implantation Trial (MADIT)-II has broadened the indications for cardioverter defibrillator implantation. We present a retrospective study designed to estimate the number of patients in Spain eligible for an implantable defibrillator according to the MADIT-II criteria. From January 1999 to October 2002, 758 consecutive patients were admitted to our center with the diagnosis of acute myocardial infarction. Sixty-seven had a left ventricular ejection fraction < or = 30% (mean, 23[5]) and were not eligible for revascularization. Excluding patients older than 80 years and patients with marked co-morbidity, 47 patients met the MADIT-II criteria for an implantable defibrillator. After a mean follow-up of 18 months, there were 20 deaths, 6 of which were considered sudden. In conclusion, application of the MADIT-II criteria for defibrillator implantation may benefit 6% of the patients with myocardial infarction in Spain. This proportion translates as 4110 defibrillator implantations.

Adult↗
PubMed1991

Automatic implantable cardioverter-defibrillator implantation without thoracotomy using an endocardial and submuscular patch system.

The automatic cardioverter-defibrillator lead system is implanted by a thoracotomy procedure that may result in atelectasis, pleural effusion, cardiac tamponade and lengthy convalescence. A new defibrillator lead system that allows selection of different defibrillating current pathways is implanted without a thoracotomy. Ten patients requiring a cardioverter-defibrillator for recurrent sustained ventricular tachycardia (five patients) or aborted sudden cardiac death (five patients) were evaluated for implantation of this lead system. A lead configuration with a bidirectional defibrillating current pathway was implanted in nine patients. The defibrillation threshold with this lead configuration was 15 J in five patients, 20 J in three and 30 to 35 J in one patient. In the remaining patient the lead system had a 40 J defibrillation threshold and was not implanted. No perioperative complications occurred. Induced ventricular fibrillation was successfully terminated at the predischarge and intermediate follow-up (8 to 12 weeks) electrophysiologic studies. During the follow-up period, there were three deaths (one sudden, two due to heart failure) and two lead system failures (oversensing with inappropriate shocks in one patient and patch lead fracture in another). Implantation of the cardioverter-defibrillator lead system by a nonthoracotomy approach is feasible, has no significant perioperative complications and is well tolerated by patients. Effective defibrillation was demonstrated immediately as well as at intermediate follow-up study. The occurrence of patch lead fracture and oversensing requires improvement in the present (nonthoracotomy) lead system technology.

Cardiac Pacing, Artificial↗
PubMed1998

Effect of implantable cardioverter-defibrillator implantation on surgical morbidity in the CABG Patch Trial. Surgical Investigators of the Coronary Artery Bypass Graft Patch Trial.

BACKGROUND: The Coronary Artery Bypass Graft (CABG) Patch Trial tested the hypothesis that prophylactic insertion of an implantable cardioverter-defibrillator (ICD) improves survival rates after high-risk CABG. We compared group-specific perioperative morbidity and mortality rates. METHODS AND RESULTS: Patients were randomized intraoperatively to undergo CABG (control subjects, n = 454) or CABG plus ICD implantation (n = 446). There were no significant differences between groups in the incidence of diabetes, ejection fraction < 0.25, end-diastolic pressure, prior myocardial infarction, or congestive heart failure. Cardiopulmonary bypass time averaged 106 minutes in control subjects and 127 minutes in the ICD group. At the inception of the trial, investigators were concerned that ICD therapy could increase surgical mortality rates or the incidence of shock, bleeding, congestive heart failure, arrhythmias, or deep sternal wound infection. Of these, only sternal wound infection was significantly more frequent in the ICD group (2.2% versus 0.4%, P < 0.05). Also more common in the ICD group were infection at a wound or catheter site (12% versus 6%), urinary tract infection (4% versus 1%), pneumonitis (8% versus 4%), respiratory insufficiency (13% versus 8%), transient central nervous system deficit (6% versus 2%), and psychotic reaction (4% versus 1%). The all-cause death rate was 6.7% in the ICD group and 4.6% for control patients (P = NS) at the time of the last surgical death, postoperative day 48. CONCLUSIONS: Epicardial ICD insertion during CABG is associated with an increase in perioperative infection. Although reporting bias may have influenced the data, if ICD insertion is indicated in CABG patients, metachronous endocardial implantation should be considered.

Adult↗
PubMed2005

[Long-lasting survival of patients with implantable cardioverter-defibrillators implanted for secondary preventive reasons].

BACKGROUND: The effectiveness of therapy with implantable cardioverter-defibrillators is usually evaluated according to the total mortality of ICD patients. The aim of this study is to analyse the total mortality of long-term followed ICD patients and to evaluate mortality according to the main diagnosis and analyse the influence of revascularization in patients with coronary artery disease. METHODS AND RESULTS: We have observed 138 consecutive patients in mean age of 62.0+/-12.2 year (108 M, 30 F) with mean LVEF 0.38+/-0.14, who had ICD implanted for malignant ventricular arrhythmias from X/95 to XII/02 from secondary preventive reasons. The mean follow-up was 47.35 months. 99 patients had coronary artery disease, 16 dilated cardiomyopathy, 5 right ventricle dysplazia, 4 LQT syndrome, 1 valvular disease and 13 pts were without structural heart disease. The total mortality of the group of patients was 22% (31 patients). The terminal heart failure was the main cause of death in our pts--in 84% of the cases. We had no sudden death in our group of pts. The highest mortality (27%) was in pts with coronary artery disease, nobody died in the group of pts without structural heart disease. The higher mortality was in patients in pts where the revascularization was not possible before ICD implantation (38% versus 20%) One-year survival of the whole group of pts covered 90% and two-year survival was 87%. CONCLUSIONS: The survival of ICD pts is shorter if coronary artery disease is present and there is no possibility to revascularize pts before ICD implantation.

Adult↗
PubMed1987

Clinical use of automatic implantable defibrillators.

We implanted the automatic implantable defibrillator model B (AID-B) in 11 patients (pts). Seven pts had coronary disease with sustained VT, and/or VF. Two had syncopal VT due to primary cardiomyopathy, and two pts had syncopal torsades de pointes (Tdp) without cardiac disease (1 long QT syndrome). These arrhythmias occurred despite antiarrhythmic drugs or beta blockers. Four pts had implanted: an epicardial patch by thoracotomy, an intra-atrial string electrode by the jugular vein, then AID-B by abdominal route. In 7 pts, subcostal approach was used, for implanting simultaneously 2 epicardial patches and the AID-B itself. During the operation, VT, Tdp and/or VF were induced in all pts by 50 Hz alternating current. The defibrillation threshold (DT) between atrial catheter and epicardial patch was less than 15 J in 4 pts, and greater than 25 J in two, requiring a larger patch in 1, and replacement of atrial electrode by another patch in the 2nd pt to obtain a DT less than 20 J. In the 6 pts implanted with 2 patches, DT was always less than 25 J. In 3 pts, DT was markedly higher for VF (25 J) than for VT (less than 15 J). One pt died from pulmonary embolism, another died after 3 years, before replacement of a failing battery, and a third died from progressive congestive heart failure, 6 months later. Eight pts are alive with a follow-up greater than 6 months. Local aseptic reactions obliged a removal of the implant in 2 pts operated by bifocal approach, and none when the subcostal route was used.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗