[Determinants of survival after implantation of an automatic defibrillator. Report of 127 patients]. / Déterminants de la survie après implantation d'un défibrillateur automatique implantable. A propos de 127 patients.

The authors present a retrospective and longitudinal study of the predictive factors of mortality in patients having an implanted automatic defibrillator. The population comprised 127 patients implanted between September 1988 and September 1997. There were 107 men with a mean age of 57.7 +/- 13 years. The left ventricular ejection fraction was 39.3%. The proportion of coronary patients was 68%; 20% of patients had atrial fibrillation and 5% were in Class III of the NYHA classification. The indications were: resuscitated cardiac arrest (N = 56) and poorly tolerated ventricular tachycardia (N = 71). The follow-up period was 30 +/- 25 months. There were 23 early and 10 late complications. Seventy-two patients had received an electric shock; 57 had an appropriate shock. There were 23 arrhythmic storms (ventricular arrhythmia requiring at least 2 shocks in less than 24 hours) in 17 patients. The operative mortality was 1.1%; at 1 year, the global survival was 93.9 +/- 2.2%; cardiac survival was 94.7 +/- 2.1%; survival without sudden death was 98.3 +/- 1.2%. Multivariate analysis isolated predictive factors for mortality; atrial fibrillation was predictive for global mortality; an ejection fraction < 30% and the fact of having received an appropriate shock were predictive of cardiac mortality; and an arrhythmic storm was predictive of sudden death.

Electrophysiologic assessment in selecting patients for multisite atrial pacing.

Electrophysiologic mechanisms of atrial fibrillation (AF) initiation are being actively studied. Multisite atrial pacing has shown, in acute studies, significant potential for prevention of AF. Dual site pacing reduces of intra and inter-atrial conduction time, atrial refractoriness dispersion, and to a limited extent atrial premature beats which modify the atrial remodelling induced by AF. Recently, two clinical trials have shown long term efficacy of multisite atrial pacing. At 3 years of follow-up, 56% of patients are free of AF recurrence with dual site right atrial pacing. Rhythm control was achieved in 86 of patients. Similar results are observed with biatrial resynchronization. In both studies, primary indication for multisite atrial pacing was AF prevention in more than 50% of patients. Selection of patients based solely on long P wave duration and prolonged interatrial conduction is not necessary as clinical outcome and comparable. These patients are comparable to patients who did not have these characteristics. Ongoing multicenter trials will likely definitively answer this question. However, preexcitation of diseased atrial regions or site of ectopic activity previously selected by high density atrial mapping or suppression of inducible AF may offer an interesting future development of multisite atrial pacing.

Factors affecting epicardial dispersion of repolarization: a mapping study in the isolated porcine heart.

OBJECTIVE: Non-uniform drug-induced prolongation of repolarization predominating in the midmyocardial (M) cell layers has been shown to be responsible for perpetuation of reentry, giving rise to torsade de pointes. However, the absence of M cells in immature animals, especially the pig, suggests other possible underlying mechanisms. We sought to examine, in this species, the effects of predisposing factors to torsade de pointes on the dispersion of epicardial repolarization and their contribution to arrhythmogenesis. METHODS: Computerized mapping of repolarization and activation was conducted on the epicardial surface in 29 Langendorff-perfused hearts of eight-week-old pigs. Activation-recovery intervals were measured simultaneously from 128 unipolar electrograms. RESULTS: Baseline iso-interval maps were dipolar (41%) or multipolar (59%). Dispersion of repolarization was reverse frequency-dependent but was unaffected by lowering [K+]o. DL-Sotalol (0.1 mmol/l) reinforced local gradients and thus increased epicardial dispersion, whereas intramural recordings did not demonstrate any predominant effect in midmyocardial layers. Phenylephrine (1 mumol/l) notably augmented DL-sotalol effects. After [Mg++]o lowering, although dispersion was not significantly increased, DL-sotalol was associated with the spontaneous occurrence of polymorphic ventricular tachycardia in seven out of nine experiments. When maps of repolarization of escape beats were compared with activation maps of first arrhythmic beats, an arc of functional dissociation was observed in the vicinity of a steep gradient of repolarization in two out of nine tachycardias. CONCLUSION: Epicardial dispersion of repolarization is increased by slow rates, DL-sotalol and phenylephrine but is not the only requirement for initiation of polymorphic ventricular tachycardia. In combination with other factors, it helps continuation of the arrhythmia in this model.

Extraction of endocardial implantable cardioverter-defibrillator leads.

Despite a growing number of implantable cardioverter-defibrillator (ICD) lead removal indications, there is no consensus about extraction techniques. We applied our experience of pacemaker lead removal to ICD leads using a superior approach with a standard extractor kit, and an inferior approach with a lasso, or a surgical extraction. Fifteen leads were removed in 11 patients during 12 procedures (1 patient was referred twice): 11 right ventricular defibrillation leads, 3 right atrial coils, and 1 atrial lead implanted with a DDD-ICD. The indication for lead extraction was insulation failure (n = 4), conductor fracture (n = 2), abdominal pocket infection (n = 4), lead endocarditis (n = 1), and replacement of an atrial coil by an atrial lead for DDD-R pacing (n = 1). One patient had surgical extraction of 2 leads because of an endocarditis with large vegetations on a DDD-ICD. In 11 other cases, 5 leads were removed using a superior approach with a standard extraction kit and 8 leads were removed by a femoral approach using a lasso alone or added to a pigtail catheter. There was no failure of explantation. One extraction attempt failed with the superior approach but was successful with a secondary inferior approach. The main difficulties encountered were due to tight adherence of the proximal coil to the venous wall and to dislodgment of passive fixation leads from their endocardial insertion. One patient had subclavian vein thrombosis after intervention; no major complication was noted. Ten patients immediately underwent reimplantation. Two patients (1 with an endocarditis and 1 free of ICD therapy for 5 years) did not have reimplantation. During a 4- to 44-month follow-up, no late complication appeared. Thus, ICD lead explantation can be performed with a good success rate, with extraction techniques similar to those used for pacemaker leads.

Extraction and reimplantation of defibrillation leads through a thrombotic subclavian vein.

Venous thrombosis is one of the most frequently encountered obstacles when reintervening on endocardial leads. We report on two patients with a ventricular defibrillator requiring lead replacement in whom a subclavian vein thrombosis was documented prior to the intervention. We recanalized the vein and replaced the lead through the same path to preserve the venous access.

Regional right and left atrial activation patterns during single- and dual-site atrial pacing in patients with atrial fibrillation.

We examined the activation of the right atrium and left atrium by pacing from different atrial sites using several single- and dual-site atrial pacing modes in patients with atrial fibrillation or flutter. We also analyzed the effect of these pacing modes on fixed coupled extrastimuli in this population. Patients underwent detailed mapping of regional right atrial (RA) and left atrial (LA) sites. Bipolar pacing was performed individually from the high right atrium, coronary sinus ostium, and the distal coronary sinus, and simultaneously from the high right atrium and coronary sinus ostium (dual-site RA pacing) or high right atrium and distal coronary sinus (biatrial pacing). Extrastimuli were delivered from the high right atrium at fixed coupling intervals of 350 and 250 ms. Twenty patients with atrial fibrillation were studied. P-wave duration during pacing was significantly abbreviated by both dual-site RA and biatrial pacing (p <0.001 vs high RA pacing, respectively) but not by any other single-site atrial pacing method. Both dual-site atrial pacing modes also significantly abbreviated P wave durations for closely coupled high RA premature beats (p <0.001) in contrast to high RA pacing. During the basic pacing drive and for high RA extrastimuli, RA activation at the crista terminalis and atrial septum was comparable in sinus rhythm, high RA pacing, and in both dual-site atrial pacing methods, but was significantly delayed by coronary sinus ostial and distal coronary sinus pacing. In contrast, proximal coronary sinus activation was delayed with high RA pacing compared with all other pacing modes, and high RA extrastimuli encountered reduced conduction delay at this location with dual-site atrial pacing modes. LA activation was advanced superiorly by both single-site coronary sinus pacing methods and both dual-site atrial pacing techniques. Inferior and lateral LA activation was advanced by all pacing modes using a coronary sinus pacing site. However, earlier activation of LA sites occurred for high RA premature beats after both dual-site pacing methods (p <0.05) compared with single-site pacing modes. Incremental conduction delay at different atrial regions for closely coupled high RA extrastimuli ranged from 33% to 120% during high RA pacing and was significantly attenuated at multiple RA and LA sites by dual-site RA and biatrial pacing. Distinct global, as well as regional electrophysiologic effects, may mediate the variable antiarrhythmic effects of different and novel atrial pacing methods.

Long-term outcome of patients with drug-refractory atrial flutter and fibrillation after single- and dual-site right atrial pacing for arrhythmia prevention.

OBJECTIVES: An initial crossover study comparing dual- and single-site right atrial pacing was performed followed by a long-term efficacy and safety evaluation of dual-site right atrial pacing in patients with drug-refractory atrial fibrillation (AF). Also examined was the efficacy of two single-site right atrial pacing modes (high right atrium and coronary sinus ostium) and the long-term need for cardioversion, antithrombotic and antiarrhythmic drug therapies during dual-site atrial pacing. METHODS: Thirty consecutive patients with drug-refractory symptomatic AF and documented primary or drug-induced bradycardia were implanted with a dual chamber rate-responsive pacemaker and two atrial leads. Single-site atrial pacing was performed at the high right atrium or the coronary sinus ostium. Continuous atrial pacing was maintained. RESULTS: Mean arrhythmia-free intervals increased from 9+/-10 days in the control period preceding implant to 143+/-110 days (p < 0.0001) in single-site right atrial pacing and 195+/-96 days in dual-site right atrial pacing (p < 0.005 versus single-site pacing and p < 0.0001 versus control). Dual-site right atrial pacing significantly increased the proportion of patients free of AF recurrence (89%) as compared to single-site right atrial pacing (62%, p = 0.02). High right atrial pacing and coronary sinus ostial pacing had similar efficacy for AF prevention. Effective rhythm control was achieved in 86% of patients during dual right atrial pacing. Seventy-eight percent of patients at 1 year and 56% at 3 years remained free of symptomatic AF. The need for cardioversion was reduced after pacemaker implant (p < 0.05) and antithrombotic therapy was reduced (p < 0.06) without any thromboembolic event. Coronary sinus ostial lead dislodgement was not observed after discharge. CONCLUSIONS: Atrial pacing in combination with antiarrhythmic drugs eliminates or markedly reduces recurrent AF. Prevention of AF is enhanced by dual-site right atrial pacing. High right atrial and coronary sinus ostial pacing do not differ in efficacy. Dual-site right atrial pacing is safe, achieves long-term rhythm control in most patients, decreases the need for cardioversion, and antithrombotic therapy can be selectively reduced.

Multisite electrode pacing for prevention of atrial fibrillation.

There is increasing evidence that single site atrial pacing is beneficial for atrial fibrillation (AF) prevention in sick sinus syndrome. Multisite atrial pacing methods such as dual site right atrial pacing and biatrial synchronous pacing are currently under active evaluation for AF and atrial flutter prevention in patients with or without bradyarrhythmias. Clinical studies have demonstrated that multisite atrial pacing has an incremental benefit as compared with single site right and left atrial pacing. The electrophysiologic rationale for the efficacy of multisite atrial pacing is based on the reduction of global and local atrial activation times during pacing and for closely coupled atrial premature beats. This results in earlier recovery of excitability and decreased conduction delay. Dual site right atrial pacing consisting of simultaneous pacing from the high right atrium and the coronary sinus ostium reduces the activation times in virtually all left and right atrial regions, especially in areas of conduction delay. Multisite pacing methods reduce the ability to initiate AF with atrial premature beats by reducing the window for AF induction and minimizing the dispersion of atrial refractoriness. In our long-term clinical experience including 30 patients with paroxysmal and chronic drug-refractory AF, 78% of the patients were free of AF recurrence at 1 year, 63% at 2 years, and 56% at 3 years. Rhythm control was achieved in 86% of patients during a follow-up period of 3 years. Concomitantly, we observed a marked reduction in need for anticoagulation, type I antiarrhythmic drugs, and cardioversion therapies. There were no coronary sinus lead-related complications during follow-up. After the initial favorable clinical experiences, two major prospective randomized trials (DAPPAF and SYNBIAPACE) are under way in North America and Europe to evaluate quantitatively the beneficial impact of multisite atrial pacing for AF prevention.

Interventional therapeutic procedures in patients with a preexisting dual site right atrial pacing system for refractory atrial fibrillation.

This report illustrates the complexity of internal atrial defibrillation and implantable cardioverter-defibrillator therapy in patients with dual site atrial pacing systems.

Differential effects of quinidine, flecainide, and cibenzoline on anisotropic conduction in the isolated porcine heart.

INTRODUCTION: Anisotropic conduction characteristics, expressed as the ratio of conduction velocities in the longitudinal (Vl) and transverse (Vt) fiber directions, may play a role in the mechanism of some ventricular tachycardias and is influenced by pharmacologic interventions. Discrepancies exist among the reported orientation-dependent effects of available Class I antiarrhythmic drugs. The aim of this study was to assess the respective effects of quinidine (Class IA), flecainide (Class IC), and cibenzoline (not subclassified) on the anisotropic conduction of porcine hearts, in corroboration of their effects on ventricular action potentials. METHODS AND RESULTS: We studied the actions of 3 and 10 microM quinidine, 1 and 3 microM flecainide, and 0.3 and 1 microM cibenzoline on Vl and Vt determined from 128 electrograms recorded with a plaque electrode on the anterior left ventricle of isolated perfused hearts (spacing 2.5 mm). Vl and Vt were computed from isochronal maps displaying ellipsoid activation during stimulation from the center of the plaque. The effects on the maximal rate of depolarization (Vmax) of action potentials were obtained from ventricular muscle exposed to the same drugs. Flecainide [1 microM] and cibenzoline [0.3 microM] did not alter Vl and Vt significantly. Quinidine [3 microM] predominantly depressed Vl at rapid pacing rates, but the Vl/Vt ratio was not significantly altered. Quinidine [10 microM] and flecainide [3 microM] reduced Vl and Vt in a frequency-dependent fashion. Conversely, cibenzoline [1 microM] mostly decreased Vl and thus decreased the Vl/Vt ratio and increased the Vl/Vt at all pacing rates. This different effect was not related to a greater depressant effect on Vmax CONCLUSION: Quinidine and flecainide act similarly on the anisotropic pattern of conduction (both drugs increase the Vl/Vt ratio), whereas cibenzoline exerts opposite effects. Orientation-dependent effects are different among Class I antiarrhythmic drugs and may be of importance in their therapeutic efficacy or proarrhythmic potential.

Risk stratification and clinical outcome of minimally symptomatic and asymptomatic patients with nonsustained ventricular tachycardia and coronary disease: a prospective single-center study.

The Multicenter Automatic Defibrillator Implantation Trial (MADIT) showed improved survival with defibrillator therapy but was restricted to coronary artery disease patients with nonsustained ventricular tachycardia (NSVT) and inducible nonsupressible VT. The outcome of patients without inducible VT or inducible but suppressed VT still remains unclear. We performed risk stratification at electrophysiologic (EP) study in 111 consecutive unselected patients with nonsustained VT and coronary artery disease and randomized them to drug or device therapy. Follow-up on selected therapy was 1-71 (mean 27 +/- 20) months. Of 111 patients, 39 patients (35%) had inducible sustained VT at baseline EP study and were stratified to a "higher" risk group (group 1) for sudden death. In 9 of these patients (group 1A), sustained VT was suppressed with class IA antiarrhythmic drugs; in the remaining 30 patients (group 1B) sustained VT was not suppressed with class IA antiarrhythmic drugs. The other 72 of 111 patients (65%) had no inducible sustained VT at EP study and were stratified to a "lower"-risk group (group 2) for sudden death. Mean LVEF in group 1 was 30 +/- 10% versus 37 +/- 9% in group 2 (p = 0.001). Selected therapy in group 1 was an implantable cardioverter defibrillator (16 patients) or guided drug therapy (electrophysiologically guided class I antiarrhythmic drugs = 7 patients; Holter-guided class III antiarrhythmic drugs = 16 patients). In group 2, empiric drug therapy included beta blockers in 29 patients or Holter-guided class III antiarrhythmic drugs in 17 patients, with no antiarrhythmic drug therapy being administered in 26 patients. Mean LVEF tended to be lower in patients receiving class III antiarrhythmic drug therapy (34 +/- 12%) than in patients receiving beta blockers (40 +/- 10%, p = 0.06). Three-year total survival was comparable in group 1 (70%) and in group 2 (81%), but sudden cardiac death mortality tended to be lower in group 1 versus group 2 (0 vs 9%, p = 0.09). Patients receiving class III antiarrhythmic therapy had significantly higher 3-year all cause (40%, p = 0.04) and sudden death (25%, p = 0.06) mortality than patients receiving beta blockers (17% and 8% respectively) or no antiarrhythmic drug therapy (4% and 0%, respectively). The following conclusions can be drawn from this analysis: (1) Electrophysiologically guided drug therapy and implantable defibrillators can minimize the risk of sudden cardiac death in patients with coronary artery disease and inducible sustained VT stratified to higher risk of sudden death. A comparable outcome with respect to sudden death prevention in drug-suppressed or drug-refractory patients suggests limited prognostic benefit of class IA drug testing. (2) Lower-risk patients with severely depressed LVEF and minimal or no symptoms do not have a favorable outcome with respect to sudden and all-cause mortality on Holter-guided class III drug therapy. However, asymptomatic patients with mildly depressed left ventricular function have low sudden death event rates on beta blocker or no antiarrhythmic drug therapy.

The role of pacemaker therapy in the prevention of atrial fibrillation.

Atrial fibrillation (AF) has been recognized, with increasing concern, as a potentially disabling illness, occurring either as a symptom of many cardiac diseases or as an isolated disorder. It can independently contribute to mortality and morbidity and may have serious prognostic importance in acute or chronic cardiac disease. In patients with symptomatic drug refractory atrial fibrillation, ventricular rate control by atrioventricular nodal ablation or modification commonly results in pacemaker implantation. The concept of AF prevention by pacemaker therapy has been introduced in patients with bradycardia-tachycardia syndrome or vagally mediated bradycardia-dependent AF. In patients with sick sinus syndrome, atrial pacing has proved to be more effective than VVI pacing in maintaining the electrical stability of the atrium in long-term follow up. Recently, the development of new techniques of atrial pacing employing pacing at two atrial sites may improve the effectiveness of the AF prevention by pacemaker therapy. Dual-site right atrial pacing using overdrive stimulation activates simultaneously the high right atrium and the left atrium via the ostium of the coronary sinus. Two main mechanisms have been proposed to explain the favourable effect of this technique. One is the suppression of atrial premature beats initiating AF by the overdrive pacing. The second is the alteration of atrial activation pattern by preexcitation of the area of the coronary sinus ostium which permits earlier recovery of excitability in sites of atrial conduction delay. The combination of drug therapy and pacing is essential for effective AF control. We have hitherto studied 30 patients with single- and dual-site pacing. Single-site pacing was performed at the high right atrium or coronary sinus ostium. The dual-site pacing mode increased the arrhythmia-free intervals, decreased patients' arrhythmia-related symptoms and anti-arrhythmic drug use as compared to the period preceding institution of pacing and incrementally over conventional high right atrial pacing alone. A multicentre randomized trial, Dual-site Atrial Pacing for Prevention of Atrial Fibrillation (DAPPAF), evaluating three pacing modes (dual-site, single-site and support pacing), is now in progress.

[Multifactor prevention of endocarditis and cardiac pacemakers. A prospective study apropos of 207 patients]. / Prévention polyfactorielle des endocardites et stimulateurs cardiaques. Une étude prospective à propos de 207 patients.

Infections after cardiac pacemaker implantation are rare (0.13 to 12.6%) but potentially severe complications. Staphylococcus is the genus most frequently isolated (72 to 100% of cases). The use of systematic prophylactic antibiotics remains controversial. From November 1991 to October 1993, 207 consecutive patients were submitted to a series of measures designed to reduce the risk of infection: a) intravenous bolus injection of Cefamindole, 15 minutes before implantation, b) cutaneous disinfection with iodinated polyvindone, c) injection of an ampoule of rifampin before closure of the pacemaker in the pouch, d) absence of drainage system. Patients were predominantly female (60.9%), with a mean age of 77 +/- 10 years, frequently suffering from heart disease (53.8%). The indication for implantation was atrioventricular block (39.7%), carotid sinus syndrome (27.5%), atrial arrhythmia (27.5%), resection of the node-His tract (5.3%). This procedure corresponded to the first implantation in 88.4% or replacement of a previous pacemaker in 11.6% of cases and the pacing mode was single-chamber (38.4% or replacement of a previous pacemaker in 11.6% of cases and the pacing mode was single-chamber (38.7%), or double chamber (61.3%). The mean duration of the procedure was 51.5 min +/- 30 min. The mean follow-up was 12.7 +/- 5 months. The overall mortality was 14% (11 cases of cardiac failure, 6 sudden deaths, 4 cerebrovascular accidents, 4 cases of pneumonia, 4 neoplasms). Only one infectious problem (endocarditis, i.e. 0.48%) was observed.