[HIS bundle pacing : Far more than an ECG cosmetic effect]. / HIS-Bundle-Pacing : Weit mehr als EKG-Kosmetik.

The therapy for heart failure in patients with uncompromised systolic ventricular function (HfpEF) is still challenging because there is an obvious lack of effective therapy options. Several of these particular patients are additionally presenting atrioventricular (AV) block. In these patients HIS bundle pacing could be a hopeful therapy strategy due to the option of an AV resynchronisation as illustrated in the following case.

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.

[Adequate performance of a pectoral implanted defibrillator after high-dose radiation therapy for thyroid cancer]. / Regelrechte Funktion eines implantierten Defibrillators nach hochdosierter Strahlentherapie unter Einbeziehung der Defibrillator-Loge.

The interference of implanted defibrillators (ICD) from electronic appliances is small. There is scant knowledge about the effects of radiation therapy on defibrillator function. Existing data commonly derive from in vitro tests of the devices. We report on a 60-year old male patient with a left pectoral implanted ICD, who received radiation therapy for treatment of thyroid cancer. The patient suffered from coronary heart disease with severely impaired left ventricular function, and had to be resuscitated from ventricular fibrillation in December 1997. A defibrillator (Medtronic Jewel 7219 C) was implanted in a left pectoral pocket. In January 2000, a carcinoma of the thyroid gland was diagnosed and treated surgically. The operation was followed by a radiation therapy with curative intention. The patient received a local dosage of 64 Gray (32 sessions in 51 days). The ICD was covered by individually sized metal blocks, and was affected by 10 Gray at maximum. The ICD was inactivated during the radiation applications to avoid inadequate therapy due to electromagnetic interference. The pace-sense parameters during 8 months of follow-up were regular. Three episodes of ventricular fibrillation were terminated adequately by the ICD. Therefore, we assumed a correct ICD funtion after radiation therapy. Radiation-induced damage of the ICD was possible. A surgical transfer of the generator out of the radiation area was rejected on ethical grounds. In the short follow-up period, the ICD function was correct. For our opinion it seems to be justified primarily to control the spontaneous outcome and ICD function at short intervals, especially in view of the poor prognosis of cancer patients.

Randomized comparison of antiarrhythmic drug therapy with implantable defibrillators in patients resuscitated from cardiac arrest : the Cardiac Arrest Study Hamburg (CASH).

BACKGROUND: We conducted a prospective, multicenter, randomized comparison of implantable cardioverter-defibrillator (ICD) versus antiarrhythmic drug therapy in survivors of cardiac arrest secondary to documented ventricular arrhythmias. METHODS AND RESULTS: From 1987, eligible patients were randomized to an ICD, amiodarone, propafenone, or metoprolol (ICD versus antiarrhythmic agents randomization ratio 1:3). Assignment to propafenone was discontinued in March 1992, after an interim analysis conducted in 58 patients showed a 61% higher all-cause mortality rate than in 61 ICD patients during a follow-up of 11.3 months. The study continued to recruit 288 patients in the remaining 3 study groups; of these, 99 were assigned to ICDs, 92 to amiodarone, and 97 to metoprolol. The primary end point was all-cause mortality. The study was terminated in March 1998, when all patients had concluded a minimum 2-year follow-up. Over a mean follow-up of 57+/-34 months, the crude death rates were 36.4% (95% CI 26.9% to 46.6%) in the ICD and 44.4% (95% CI 37.2% to 51.8%) in the amiodarone/metoprolol arm. Overall survival was higher, though not significantly, in patients assigned to ICD than in those assigned to drug therapy (1-sided P=0.081, hazard ratio 0.766, [97.5% CI upper bound 1.112]). In ICD patients, the percent reductions in all-cause mortality were 41.9%, 39.3%, 28. 4%, 27.7%, 22.8%, 11.4%, 9.1%, 10.6%, and 24.7% at years 1 to 9 of follow-up. CONCLUSIONS: During long-term follow-up of cardiac arrest survivors, therapy with an ICD is associated with a 23% (nonsignificant) reduction of all-cause mortality rates when compared with treatment with amiodarone/metoprolol. The benefit of ICD therapy is more evident during the first 5 years after the index event.

[High frequency current ablation of supraventricular tachyarrhythmias in congenital heart defects]. / Hochfrequenzstromablation supraventrikulärer Tachyarrhythmien bei angeborenen Herzfehlern.

Supraventricular tachycardia is a frequent cause of disease in patients with congenital heart defects and has a potentially high impact on quality of life, morbidity and mortality of this patient cohort. Conventional treatment often fails to avoid recurrences of tachycardia in a long-term perspective. Potential side effects of antiarrhythmic drugs include aggravation of heart disease related disturbances of impulse generation and conduction properties or negative inotropic effects on haemodynamically impaired ventricular chambers. For these reasons, interventional electrophysiology is increasingly used for the treatment of supraventricular tachycardias in patients with congenital heart disease. Until March 1998 a total of 83 patients with congenital heart defects underwent an attempt for radiofrequency current treatment of supraventricular tachycardias. Among these were 36 children with an age of 5 months to 15 years (8.2 +/- 4.6 years) and 4.7 grown ups with an age of 17 to 76 years (39.3 +/- 14.3 years). In a natural course or preoperative status of the congenital heart disease were 35 patients, while palliative or corrective surgery was performed in 48 patients. Supraventricular tachycardia was based on a total of 63 congenital arrhythmogenic substrates, among them were 53 accessory pathways, 4 Mahaim fibres, 5 functionally dissociated AV-nodes and an anatomically doubled specific conduction system including 2 distinct AV-nodes in one case. In the remaining patients with tachycardia based on acquired arrhythmogenic substrates there were 45 incisional atrial reentrant tachycardias, 15 atrial flutters of the common type and 6 ectopic atrial tachycardias. In a total of 105 sessions 78 of the 83 patients were successfully treated with the use of radiofrequency current ablation. There were no significant procedure related complications. Radiofrequency current ablation can be carried out safely and successfully for the treatment of supraventricular tachycardia in young and adult patients with congenital heart disease. As such therapeutic strategy meets the specific requirements of this patient cohort, early consideration for this therapy is recommended.

Data base management in interventional electrophysiology--the relational advantage.

UNLABELLED: A relational database was designed to facilitate patient management and storage of complex electrophysiologic data of patients undergoing radiofrequency catheter ablation. The database has to deal with multiple data entries per patient record like radiofrequency current applications and catheters. BACKGROUND: Due to the complexity of catheter mapping and ablation therapy, the investigators have to handle various data types. Contradictory to a flat-file database, a relational structured database is not limited to a "single record structure". IMPLEMENTATION: The designed database is built on the relational database programming environment 4th Dimension (ACI). It is implemented on an Apple Macintosh computer system. The relational structure consists of 13 data files and enables an unlimited data entry of multiple items per data field: In 1288 patients 10308 radiofrequency current applications were applied for ablation therapy and 4798 diagnostic or therapeutic catheters were used.

[Anatomic distribution, conduction properties and recurrences after ablation of multiple in comparison with single accessory conduction pathways]. / Anatomische Verteilung, Leitungseigenschaften und Rezidivverhalten nach Ablation von multiplen im Vergleich zu singulären akzessorischen Leitungsbahnen.

In 1076 consecutive patients referred for radiofrequency current catheter ablation, the anatomical distribution and conduction properties of accessory pathways (APs) as well as the mode of recurrence after ablation were retrospectively analyzed and compared in patients with multiple and single APs. Except for 17 patients with Ebstein's anomaly, the prevalence of patients of multiple APs in this cohort was 5.4%. Patients with multiple APs. as opposed to patients with a single AP, had significantly more often APs located on the right free wall (23% versus 10%) and--since the prevalence of septal APs was identical in both groups--less frequently APs located on the left free wall (44% versus 56%). Also, concealed APs were significantly more often encountered in patients with multiple APs (45% versus 24%). Recurrence of conduction across an AP which had presumably been ablated was observed in both groups with statistically equal incidence of < 5%. In 11 patients with multiple APs, the additional AP was only found at the repeat session. These "new" APs were mostly concealed (9 out of 11) and necessitated an intervention predominantly late after the initial ablation session. Intermittent concealed conduction appears to be a likely explanation for this phenomenon. Patients with multiple APs exhibit a higher incidence of right free-wall and concealed APs, yet they stand the same, approximately 95%, chance of cure as do patients with a single AP. Nearly 25% percent of repeat sessions in patients initially thought to have a single AP are caused by the late manifestation of an additional AP.

Radiofrequency catheter ablation of left atrial tachycardia originating within the pulmonary vein in a patient with dextrocardia.

A case is presented of a 38-year-old male with dextrocardia in whom radiofrequency current ablation of an incessant atrial tachycardia originating within the infero-lateral pulmonary vein was achieved. Activation mapping with detection of the earliest atrial activation was used for identification of the arrhythmogenic focus. In addition to fluoroscopy, transesophageal echocardiography was used for catheter guidance during the transseptal puncture. The present experience suggests that location of an arrhythmogenic focus within the pulmonary venous system should be considered whenever early atrial activation during ectopic atrial tachycardia is recorded at the junction between the left atrium and the pulmonary veins.

Therapeutic consequences of newer studies addressing the problem of myocardial ischemia and ventricular arrhythmias.

Direct evidence from pathologic-anatomical studies in victims of sudden cardiac death has been given for acute ischemia (caused by either an acute thrombus, plaque fissuring or an organizing thrombus) to play a major role in the genesis of sudden cardiac death. Furthermore, indirect data on the effects of drugs in the setting of acute myocardial infarction have demonstrated that treating patients with beta-blocking agents is more beneficial than treating them with a pure anti-arrhythmic drug such as lidocaine. Whereas lidocaine, which also reduces the incidence of ventricular fibrillation in the setting of acute myocardial infarction, may produce an excess of mortality, beta-blockers reduce ventricular fibrillation and are associated with a prolonged survival. Further, indirect evidence on the role of ischemia in ventricular arrhythmias is given in patients with chronic ischemic heart disease by several studies on coronary revascularization and by studies on antiarrhythmic drugs versus beta-blockers in the same situation. In conclusion, there is clear evidence from studies of coronary revascularization and from studies on drug intervention in different patient populations with ischemic heart disease at risk for ventricular arrhythmias and/or for sudden cardiac death that ischemia plays an important role in the genesis of these arrhythmias.

[The implantable cardioverter/defibrillator]. / Der implantierbare Kardioverter/Defibrillator.

Despite all advances in the diagnosis and therapy of cardiovascular diseases, the mortality from malignant ventricular tachyarrhythmias is still a major health problem. In addition to established therapeutic strategies in the prevention of sudden cardiac death such as antiarrhythmic drug treatment, catheter ablation or antiarrhythmic drug treatment, cardioverter/defibrillator was introduced to clinical practice in 1980. The number of 50,000 overall implants reflects the current clinical status of the therapy with implantable cardioverter/defibrillators. Significant technical improvements in the defibrillator therapy may contribute to an increase in therapy acceptance. These advances include the introduction of nonthoracotomy lead systems, enhanced defibrillation efficacy, full programmable devices providing tiered electrical therapy, improved diagnostic Holter functions and enhanced arrhythmia detection algorithms. The major present goals of defibrillator therapy are detection and termination of malignant ventricular tachyarrhythmias, prevention of sudden cardiac death, reduction in patient's mortality and improvement in quality of life. The efficacy and safety of defibrillator therapy to prevent sudden arrhythmic death has been proven in several large clinical investigations In patients with this device the annual sudden cardiac death mortality is < 2% even in high-risk patient populations. Compared to sudden cardiac death rate there is a much higher rate of overall cardiac mortality because a defibrillator is not able to prevent nonarrhythmic cardiovascular deaths. There is a clinical impression that cardiovascular mortality is lower in patients treated with an implantable cardioverter/defibrillator compared to patients treated with other therapies. However, there are no results from controlled studies providing scientific evidence that defribillator therapy can decrease overall cardiovascular mortality.(ABSTRACT TRUNCATED AT 250 WORDS)

Catheter-induced mechanical conduction block of right-sided accessory fibers with Mahaim-type preexcitation to guide radiofrequency ablation.

BACKGROUND: Accessory pathways originating at the tricuspid annulus that exhibit decremental antegrade conduction properties (Mahaim-type preexcitation) are amenable to radiofrequency (RF) current catheter ablation. However, a reliable and reproducible strategy for mapping and ablation of these fibers is lacking. METHODS AND RESULTS: Eleven patients with preexcited atrioventricular tachycardia involving a decrementally conducting antegrade accessory pathway underwent complete electrophysiological evaluation and subsequent attempts at RF catheter ablation. Mechanical conduction block at the subannular level of the atrial input to the accessory fiber was induced by catheter manipulation in 8 patients, in 2 of them during atrial fibrillation. RF current was delivered, after resumption of preexcitation, to the site of mechanical block during atrial pacing (n = 6) or atrial fibrillation (n = 2) and eliminated the accessory pathway in all 8 patients. In another patient, mechanical block was not observed, but ablation of the atrial accessory fiber insertion was achieved at the subannular level during atrioventricular tachycardia. The anatomic site of ablation along the tricuspid annulus was anterolateral (n = 1), lateral (n = 3), or posterolateral (n = 5). Failures were encountered in the first patient of the series in whom ablation attempts were directed at the ventricular insertion of the accessory fiber and in a patient in whom ablation of the atrial insertion was attempted at the supraannular level. Recurrence of preexcitation within 12 hours was observed in 5 of 6 patients in whom ablation had been achieved during atrial pacing. Eventually successful repeat sessions were performed the following day using a simplified ablation approach. Thus, a median of 5 RF pulses (range, 1 to 26) per accessory fiber eliminated conduction in 9 (82%) of the 11 patients in 1.9 +/- 0.9 sessions. During a follow-up of 9.5 +/- 2.3 months, preexcitation recurred in 1 patient. CONCLUSIONS: The atrial origin of accessory connections with Mahaim-type preexcitation is apparently confined to the anterolateral-to-posterolateral region of the tricuspid annulus. Mechanical conduction block in the atrial input to the accessory fiber induced at the subannular level by catheter manipulation provides an optimal marker to locate the ablation site, even during atrial fibrillation. To expose early recurrence of antegrade accessory pathway conduction, intermittent atrial pacing in the 12 hours after ablation is advisable; in cases of recurrence, a repeat procedure can readily be performed using just the ablation catheter advanced to the target site at the tricuspid annulus.

Potential of intracardiac ultrasonography as an adjunct for mapping and ablation.

Radio frequency catheter ablation of cardiac tissues has evolved rapidly as the standard therapy for various arrhythmias. Current mapping techniques include fluoroscopy and endocardial ECG recordings. These techniques are time-consuming and give only limited information with regard to cardiac anatomy and pathology. Moreover, fluoroscopy leads to significant radiation exposure to the patient and the operator. Intracardiac ultrasonography is a promising new technique that may improve intracardiac anatomic orientation, reduce radiation exposure, allow better control of lesion formation during radio frequency current application, and identify possible complications such as thrombus formation or perforation. Intracardiac ultrasonography systems that are presently available are limited by insufficient penetration depth and image resolution. Technical refinements are discussed that may improve the applicability of intracardiac echocardiography for electrophysiologic mapping procedures.

Implantable cardioverter defibrillator compared with antiarrhythmic drug treatment in cardiac arrest survivors (the Cardiac Arrest Study Hamburg).

In 1987, the Cardiac Arrest Study Hamburg (CASH), a prospective, multicenter, randomized controlled study, was started in survivors of sudden cardiac death resulting from documented ventricular tachyarrhythmias. Through December 1991, 230 survivors (46 women, 184 men; mean age 57 +/- 11 years) of cardiac arrest caused by ventricular tachyarrhythmias were randomly assigned to receive either oral propafenone (56 patients), amiodarone (56 patients), or metoprolol (59 patients) or to have an implantable defibrillator (59 patients) without concomitant antiarrhythmic drugs. The primary endpoint of the study was total mortality. In March 1992, the propafenone arm of CASH was stopped because of excess mortality compared with the implantable defibrillator group. This article presents preliminary results of the comparison of implantable defibrillator therapy with propafenone therapy. A significantly higher incidence of total mortality, sudden death (12%), and cardiac arrest recurrence or sudden death (23%) was found in the propafenone group compared with the implantable defibrillator-treated patients (0%, p < 0.05). It was concluded that, in survivors of cardiac arrest, propafenone treatment is less effective than implantable defibrillator treatment.

Preliminary results of the Cardiac Arrest Study Hamburg (CASH). CASH Investigators.

Sodium channel blockers and class III antiarrhythmic compounds, as well as beta blockers, have been used in preventing recurrences of sudden cardiac death. In recent years, implantable cardioverter-defibrillators (ICDs) have been used increasingly, but no data from randomized trials comparing antiarrhythmic drug and ICD therapy have been reported in this setting. In 1987, the Cardiac Arrest Study Hamburg (CASH), a prospective, randomized trial, was initiated to compare metoprolol, amiodarone, propafenone, and ICD implantation in patients surviving sudden cardiac death due to documented ventricular tachycardia and/or ventricular fibrillation. The details of the study design and preliminary results are presented herein. The primary endpoint of the study is total mortality. The data reviewed in March 1992, representing a mean follow-up period of 11 months, indicated no significant differences among patients randomized to metoprolol, amiodarone, and ICDs. However, there was a significantly higher total mortality and cardiac arrest recurrence in patients randomized to propafenone compared with those randomized to the ICD treatment limb. The study continues with the deletion of the propafenone treatment limb.

[The predictors of success in the radiofrequency ablation of left accessory pathways using the single-catheter technic]. / Predictores de éxito en la ablación de vías accesorias izquierdas mediante radiofrecuencia utilizando la técnica del catéter único.

INTRODUCTION AND OBJECTIVES: To determine the predictors of successful radiofrequency current ablation of an accessory pathway using the single-catheter approach, we retrospectively analyzed 46 consecutive patients with left sided accessory atrioventricular pathways and manifest preexcitation. METHODS: Ablation using a single catheter advanced retrogradely towards the mitral valve was successful in 42 (91%). A radiofrequency pulse resulting in permanent accessory pathway block was defined as a successful pulse; a pulse that had no effect or caused only transient accessory pathway block was defined as an unsuccessful pulse. RESULTS: Successful radiofrequency pulses (n = 37) did not differ from those that failed (n = 56) in the local atrium-accessory pathway potential interval, in the accessory pathway-ventricle interval nor in the cumulative energy delivered. But in successful radiofrequency pulses, the amplitude ratio of local atrium and ventricular potentials tended to be larger (0.29 +/- 0.17 vs 0.23 +/- 0.17; p = 0.053) and presumed accessory pathway potential was more often recorded (36 [97%] vs 38 [68%]; p = 0.006). The time elapsed from the beginning of the current application and the accessory pathway block was shorter in successful pulses as compared to those pulses producing only transient block (3.3 +/- 2 s vs 6.9 +/- 4 s). CONCLUSIONS: The recording of a presumed accessory pathway potential, a large local A/V ratio and the occurrence of early conduction block in the accessory pathway were the best predictors of successful radiofrequency current application using the single-catheter approach.

[Low energy cardioversion with the implantable cardioversion defibrillator devices for treatment of ventricular tachycardia and ventricular fibrillation]. / Niederenergetische Kardioversion mittels implantierbarer Kardioversions-Defibrillationsgeräte (ICD) zur Behandlung von ventrikulären Tachykardien und Kammerflimmern.

Programmable implantable cardioverter-defibrillators (ICD) with low energy capabilities for the treatment of ventricular tachycardia were introduced to increase patients acceptance and lengthen battery life. However, no data about efficacy and safety of low energy cardioversion with subsequent defibrillation in ventricular tachycardia and fibrillation are available. Nineteen of 42 patients with documented or inducible ventricular tachycardia before ICD implantation were studied. In all patients the effectiveness of low-energy cardioversion (< or = 4 joules) with subsequent high-energy defibrillation was evaluated in monomorphic ventricular tachycardia and/or ventricular fibrillation. During predischarge programmed stimulation in 13/19 patients, a total of 32 monomorphic ventricular tachycardias occurred, and in only six patients could ventricular fibrillation be induced. A tachycardia-related efficacy of 69% and patient-related efficacy of 46% of the low-energy cardioversion < or = 4 joules was observed. Ten tachycardias were accelerated to ventricular fibrillation or remained unchanged (n = 2). The second shock (energy > 17 joules) terminated seven arrhythmias, whereas a third (30 joules) shock or an external defibrillation (n = 2) was necessary for termination of the remaining three arrhythmias. After induction of ventricular fibrillation as the primary arrhythmia, the first (low-energy) shock terminated 2/16 episodes, whereas the second (high-energy) shock reverted ventricular fibrillation in 11/16 episodes. In one patient, a second high energy shock and in two patients external defibrillation was necessary for conversion of ventricular fibrillation. In one patient, an increase of the defibrillation threshold induced by amiodarone could be identified.(ABSTRACT TRUNCATED AT 250 WORDS)

[Outpatient diuretic treatment of terminal heart failure by a completely implantable venous infusion system]. / Ausserstationäre diuretische Behandlung der terminalen Herzinsuffizienz durch vollständig implantierbare venöse Infusionssysteme.

In severe heart failure with peripheral and enterohepatic congestion resistance to diuretics with inactivation of oral furosemide is a common finding. Impaired bioavailability is most likely related to pharmacodynamic and especially to pharmacokinetic reasons. To ensure efficient drug delivery and effective treatment with diuretics, venous access devices (port-systems) were implanted in 10 patients (eight men and two women, age between 57 and 80 years). All patients were in heart failure functional class III-IV and had a history of recurrent episodes of severe decompensation; none was suitable for heart transplantation. Injections of furosemide and other drugs were performed 1-4 times a day; one female patient performed the intravenous injections herself, in three cases the partners and in six cases the practitioner or an outpatient nurse performed the injections. All patients were treated on an outpatient basis, i.e., at home or in nursing homes. The port-implantation was followed up between 30 and 742 days (1-24 months); no serious complications were observed. Both patients and their partners were considered to well tolerate and accept the port-systems. Totally implantable venous access devices promise to reduce the number and severeness of cardiac decompensations in chronic preterminal heart failure by application of daily intravenous furosemide. This form of outpatient treatment will ameliorate the quality of life and stabilize the course of these severely and chronically ill patients.

[Prospective long-term ECG study of 100 patients surviving sudden cardiac death]. / Prospektive Langzeit-EKG-Untersuchung von 100 Patienten mit überlebtem plötzlichem Herztod.

One hundred survivors of sudden death were randomized to four groups and treated with Amiodarone, Propafenone and Metoprolol, or were supplied with an automatic implantable cardioverter/defibrillator (AICD, control group). Prospective Holter-monitoring showed that the prognostic significance of the complexity and frequency of ventricular ectopic activity in survivors of sudden cardiac death is relative to the chosen prophylactic antiarrhythmic treatment: Findings in the control group confirm the classical notion that frequent and complex ventricular ectopic activity is predictive for recurrent life-threatening ventricular tachyarrhythmias (relapse) (> or = 25 VES/h, p < 0.05; Lown IVb, just short of statistical significance). Therapy with Amiodarone reduced frequent and complex ventricular ectopic activity as well as the 2-year relapse rate, which was significantly lower than in the control group (AICD: 36%, Amiodarone 12%, p = 0.03). Under Metoprolol the frequency and complexity of ectopic ventricular activity increased, yet the relapse rate was reduced (12%, p = 0.03). Under Propafenone, especially, those patients who showed low frequencies of ventricular ectopic activity were at high risk; the 2-year relapse rate was 28%.

Efficacy of automatic multimodal device therapy for ventricular tachyarrhythmias as delivered by a new implantable pacing cardioverter-defibrillator. Results of a European multicenter study of 102 implants.

BACKGROUND: Third-generation implantable cardioverter-defibrillators are devices designed to treat ventricular tachycardia (VT) and ventricular fibrillation (VF) by means of overdrive pacing, cardioversion, or defibrillation. So far, the efficacy of tiered therapy has been documented only in small series. Therefore, a European multicenter clinical evaluation study of a new tachyarrhythmia control device, the Medtronic PCD pacer-cardioverter-defibrillator with epicardial patch-lead configuration, was undertaken. METHODS AND RESULTS: We report on 102 patients (mean age, 55 +/- 13 years) from 11 European centers. PCD devices implanted between May 1989 and February 1991 were included. The patients suffered from hemodynamically significant ventricular tachyarrhythmias not suppressed by antiarrhythmic drug therapy and unrelated to acute myocardial infarction; one patient had nonsustained VT and severely depressed left ventricular function. Seventy patients had coronary artery disease with old myocardial infarctions, 23 had cardiomyopathies of various etiologies, and nine patients had no detectable heart disease. Mean ejection fraction was 36 +/- 14% (range, 10-76%). Mean intraoperative defibrillation threshold (51 patients) was 10.6 +/- 5.1 J (range, 2-18 J). The documented follow-up ranged from 1 to 21 months (mean, 9.4 +/- 5.8 months), or 79.9 cumulative patient-years. Perioperative mortality was 3.9%. The actuarial survival rate at 12 months was 91%. One sudden arrhythmic death occurred. Sixty patients (58%) received device therapy. Seventeen patients had therapies only for "VF" episodes, 16 patients only for VT, and 28 patients for VT and "VF" episodes. Based on device memory data, 1,235 spontaneous VT episodes were detected and treated in 43 patients. Twelve hundred four of these VT episodes received painless initial antitachycardia pacing therapy, restoring sinus rhythm in 91%. The 108 ongoing episodes received 209 multiple therapeutic attempts. Eighty-five additional overdrive pacing therapies restored sinus rhythm in 30%. Initial ineffective antitachycardia pacing therapies received 51 cardioversion pulses. The success rate was 61%. Seventy-three additional cardioversion pulses were delivered to backup ineffective pacing therapy as well as ineffective secondary cardioversion pulses. Their success rate was only 40%. Two hundred eighty-six spontaneous episodes were detected in 44 patients as "VF." Overall defibrillation efficacy was 97.6%. CONCLUSIONS: The implanted device nearly eliminates sudden arrhythmic death in patients with documented, potentially fatal ventricular tachyarrhythmias. Automatic tiered therapy is highly effective to restore sinus rhythm, provided that an integrated two-zone tachycardia detection algorithm is used, assigning lower tachycardia rates to overdrive pacing and/or cardioversion and higher tachycardia rates to defibrillation. In general, spontaneous VTs can be terminated by automatic overdrive pacing, and painful or disturbing countershock therapies are not required to terminate the majority of spontaneous VT episodes.