Clinical Results with Electrophysiologist-Implanted Cardioverter-Defibrillators

With the advent of nonthoracotomy leads and smaller devices. implantation techniques for implantable cardioverters defibrillators (ICDs) have been simplified. We reviewed the outcome of pectoral ICD implantation by electrophysiologists in 51 consecutive patients, 47 males and 4 females, mean age 60 ± 12 years, presenting with aborted sudden cardiac death (14) and drug refractory hypotensive ventricular tachycardia (37). Patients were implanted with either the PCD Jewel^TM 7219D (37) or 72197C (14) Medtronic pectoral ICDs. The mean operative time was 98 ± 31 minutes. There was no operative mortality. Complications occurred in 2 (4%) patients: right ventricular lead dislodgement requiring lead repositioning occurred in 1 patient, and 1 patient treated with anticoagulants, who had received a subcutaneous patch lead, developed a hematoma not requiring surgical reintervention. The mean defibrillation threshold was 18.6 ± 5.5 J, but was significantly lower for the 7219C(14.1 ± 5.0 J) compared to the 7219D (20.6 ± 4.4J) device, P = 0.0001. A two-lead system consisting of a right ventricular electrode (RVA) and a superior vena caval lead (SVC) was utilized in 29, RVA/SVC-subcutaneous patch in 5 and active can in 17 patients, Patients were discharged after 4.3 ± 3 days. The procedure time was significantly shorter for the 7219C device (79.7 ± 18.9 vs 105.2 ± 32.8 minutes., P = 0.0035]. Over the fallow-up period of 8 ± 5 (range 1–20] months, 26% patients received appropriate therapy (95% antitachycardia pacing, 5% shock). Concomitant antiarrhythmic therapy was utilized in 41% of patients. Ninety-eight percent of patients are alive. One patient died of congestive heart failure. Clinical results with electrophysiologist-implanted pectoral ICDs demonstrate lou morbidity and no operative mortality in this clinical series and lower DFTs and shorter procedure times may be achieved with 7219C (active can) device.     

Left Ventricular Ejection Fraction as Criterion for Implantation of an Implantable Cardioverter-Defibrillator in Heart Failure Patients Undergoing Surgical Left Ventricular Reconstruction

Background: Besides implantation of an implantable cardioverter-defibrillator (ICD), a proportion of patients with left ventricular (LV) dysfunction due to ischemic cardiomyopathy are potential candidates for surgical LV reconstruction (Dor procedure), which changes LV ejection fraction (LVEF) considerably. In these patients, LVEF as selection criterium for ICD implantation may be difficult. This study aimed to determine the value of LVEF as criterium for ICD implantation in heart failure patients undergoing surgical LV reconstruction.
Methods: Consecutive patients with end-stage heart failure who underwent ICD implantation and LV reconstruction were evaluated. During admission, two-dimensional (2D) echocardiography (LV volumes and LVEF) was performed before surgery and was repeated at 3 months after surgery. Over a median follow-up of 18 months, the incidence of ICD therapy was evaluated.
Results: The study population consisted of 37 patients (59 ± 11 years). At baseline, mean LVEF was 23 ± 5%. Mean left ventricular end-systolic volume (LVESV) and left ventricular end-diastolic volume (LVEDV) were 175 ± 73 mL and 225 ± 88 mL, respectively. At 3-month follow-up, mean LVEF was 41 ± 9% (P < 0.0001 vs. baseline), and mean LVESV and LVEDV were 108 ± 65 mL and 176 ± 73 mL, respectively (P < 0.0001 vs. baseline). During 18-month follow-up, 12 (32%) patients had ventricular arrhythmias, resulting in appropriate ICD therapy. No significant relations existed between baseline LVEF (P = 0.77), LVEF at 3-month follow-up (P = 0.34), change in LVEF from baseline to 3-month follow-up (P = 0.28), and the occurrence of ICD therapy during 18-month follow-up.
Conclusion: LVEF before and after surgical LV reconstruction is of limited use as criterium for ICD implantation in patients with end-stage heart failure.     

Comparison of Three Cardioverter Defibrillator Implantation Techniques: Initial Results with Transvenous Pectoral Implantation

A total of 121 patients underwent epicardial (n = 32), transvenous abdominal (n = 30), and transvenous pectoral (n = 59) ICD implants. Perioperative complications were defined as those occurring within 30 days after surgery. Hospital costs were calculated with $750 per day as a fixed charge. Duration of surgery was the time between the first skin incision and the last skin suture. Severe perioperative complications that were life-threatening or required surgical intervention occurred in the epicardial (6%) and transvenous (10%) abdominal groups, but not in the pectoral group. Perioperative mortality occurred only in the epicardial abdominal group, predominantly in patients with concomitant surgery (18%), and in 5% of patients without concomitant surgery. The duration of surgery was significantly shorter for transvenous pectoral implantation (58 ± 15 rain, P < 0.05) compared to transvenous abdominal implantation (115 ± 38 min). Epicardial abdominal ICD implantation had the longest procedure time (154 ± 31 min). The postimplant hospital length of stay was significantly shorter for pectoral implantation (5 ± 3 days, P < 0.05) compared to transvenous (13 ± 5) and epicardial (19 ± 5) abdominal implantation. Total hospitalization costs significantly decreased in the pectoral implantation group ($4,068 ±$2,099 for the pectoral group vs $14,887 ±$4,415 and $9,975 ±$3,657 for the epicardial and the transvenous abdominal group, respectively, P < 0.05). These initial results demonstrate the advantage of transvenous pectoral ICD implantation in terms of perioperative complications, procedure time, hospital length of stay, and hospitalization costs.     

Pectoral cardioverter defibrillators: comparison of prepectoral and submuscular implantation techniques

The purpose of this study was to compare the two techniques of pectoral ICD implantation, prepectoral and submuscular, performed by an electrophysiologist in the catheterization laboratory with use of general or local anesthesia in 45 consecutive patients. Over a period of 30 months, we implanted pectoral transvenous ICDs in 43 men and 2 women, aged 59 +/- 12 years, with use of general (n = 20) or local (n = 25) anesthesia in the catheterization laboratory. Patients had coronary (n = 30) or valvular (n = 4) disease, cardiomyopathy (n = 10) or no organic disease (n = 1), a mean left ventricular ejection fraction of 31%, and presented with ventricular tachycardia (n = 40) or fibrillation (n = 5). One-lead ICD systems (18 Endotak, 10 Transvene/8 Sprint, 2 EnGuard) were used in 38 patients, 2-lead (5 Transvene, 1 EnGuard) systems in 6 patients, and 1 atrioventricular lead ICD system in 1 patient. The prepectoral technique was employed in 29 patients with adequate subcutaneous tissue, while the submuscular technique was used in 16 patients who had a thin layer of subcutaneous tissue. The defibrillation threshold averaged 9-10 J in both groups and there were no differences in pace/sense thresholds. All implants were entirely transvenous with no subcutaneous patch. Biphasic ICD devices were employed in all patients. Active or hot can devices were used in 39 patients. There were no complications, operative deaths, or infections. Patients were discharged at a mean of 3 days. All devices functioned well at predis-charge testing. Over 14 +/- 8 months, 20 patients received appropriate device therapy (antitachycardia pacing or shocks). No late complications occurred. One patient died at 3 months of pump failure; there were no sudden deaths. In conclusion, for exclusive pectoral implantation of transvenous ICDs, electrophysiologists should master both prepectoral and submuscular techniques. One can thus avoid potential skin erosion or need for abdominal implantation in patients with a thin layer of subcutaneous tissue. Finally, there are no differences in pacing or defibrillation thresholds between the two techniques.     

Transvenous Atrial Cardioversion Threshold in Patients with Implantable Cardioverter Defibrillator: Influence of Active Pectoral Can

Recent studies have shown that transvenous atrial cardioversion is feasible with lead configurations primarily designed for implantable cardioverter defibrillators (ICD). The purpose of this study was to examine the influence of an active pectoral ICD can on the atrial cardioversion threshold (ADFT). Forty consecutive patients received a transvenous single lead system (Endotak DSP 0125, CPI, St. Paul, MN, USA) in combination with a left subpectoral ICD (Ventak Mini, CPI) for treatment of malignant ventricular tachyarrhythmias. Patients were randomized into two groups: 21 received a Hot Can 1743 and 19 patients a Cold Can 1741. Step-down testing of the ventricular defibrillation threshold (VDFT) was performed intraoperatively and evaluation of the ADFT for induced atrial fibrillation (AF) at predischarge. After testing, each patient received a 2-J shock and was asked to quantify discomfort on a numerical scale ranging from 0 to 10. Both groups were comparable with regard to all clinical parameters studied. The mean VDFT in patients with a Hot Can device was significantly lower than in patients with a Cold Can (7.5 ± 2.3 J vs 9.8 ± 3.8 J; P < 0.03). The mean ADFT in the Hot Can group tended to be lower than in the group with Cold Cans (3.4 ± 1.4 J vs 4.5 ± 2.4 J; P = 0.07), and the proportion of patients in whom atrial cardioversion was accomplished at low energies (≤ 3 J) was higher in patients with active compared with patients with inactive pulse generators (57% vs 26%; P < 0.04). The mean discomfort reported after delivery of a 2-J shock was comparable in both groups (Hot Can 5.2 ± 1.9; Cold Can: 5.3 ± 2.1; P = NS). We conclude that the inclusion of an active left subpectoral can in the defibrillation vector of a ventricular ICD seems to reduce the energy requirements for atrial cardioversion without increasing the discomfort caused by low energy shocks.     

Defibrillation Thresholds and Perioperative Mortality Associated with Endocardial and Epicardial Defihrillation Lead Systems

Defibrillation thresholds (DFT) and perioperative mortality were evaluated in 123 patients who had endocardial defibrillation leads implanted in conjunction with the Medtronic model 7216A/7217 (Medtronic, Inc.) cardioverter-defibrillator (ICD). Clinical variables, implant DFTs, and 30-day perioperative mortality were compared with 266 patients who had the ICD implanted with epicardial defibrillation leads. The two groups were comparable in age, gender, and incidence of coronary artery disease. New York Heart Association Class I and II were more frequent in patients with endocardial leads (87.7%) as compared to those with epicardial leads (78.8%; P < 0.001). Mean left ventricular ejection fraction was significantly higher in patients with the endocardial lead system (37% vs 33%; P < 0.05). A significant proportion of patients with epicardial lead systems underwent another cardiac surgical procedure at the time of ICD implantation (13.9%) as compared to none in those who had endocardial leads implanted (P < 0.001). All patients with endocardial leads had implantation of triple lead systems as compared to 53.4% with epicardial leads (P < 0.001). The mean DFT at implant was lower in epicardial lead recipients (8.9 J) as compared to endocardial lead recipients (13.3 J; P < 0.001). Perioperative mortality had a significant trend to lower risk for endocardial lead systems (0.8%) as compared to epicardial systems (4.2%; P = 0.07). We conclude that this endocardial lead system has additional electrode and higher defibrillation energy requirements than the epicardial lead systems used with the Medtronic pacemaker ICD. However, the use of endocardial nonthoracotomy defibrillation leads is associated with a markedly reduced perioperative risk of ICD implantation. This could be due to patient characteristics, a less invasive implant procedure, and absence of concomitant cardiac surgery.     

A randomized prospective study of single coil versus dual coil defibrillation in patients with ventricular arrhythmias undergoing implantable cardioverter defibrillator therapy

ICD implantation is standard therapy for malignant ventricular arrhythmias. The advantage of dual and single coil defibrillator leads in the successful conversion of arrhythmias is unclear. This study compared the effectiveness of dual versus single coil defibrillation leads. The study was a prospective, multicenter, randomized study comparing a dual with a single coil defibrillation system as part of an ICD using an active pectoral electrode. Seventy-six patients (64 men, 12 women; age 61 +/- 11 years) were implanted with a dual (group 1, n = 38) or single coil lead system (group 2,n = 38). The patients represented a typical ICD cohort: 60% presented with ischemic cardiomyopathy as their primary cardiac disease, the mean left ventricular ejection fraction was 0.406 +/- 0.158. The primary tachyarrhythmia was monomorphic ventricular tachyarrhythmia in 52.6% patients and ventricular fibrillation in 38.4%. There was no significant difference in terms of P and R wave amplitudes, pacing thresholds, and lead impedance at implantation and follow-up in the two groups. There was similarly no difference in terms of defibrillation thresholds (DFT) at implantation. Patients in group 1 had an average DFT of 10.2 +/- 5.2 J compared to 10.3 +/- 4.1 J in Group 2, P = NS. This study demonstrates no significant advantage of a dual coil lead system over a single coil system in terms of lead values and defibrillation thresholds. This may have important bearing on the choice of lead systems when implanting ICDs.     

Worldwide Clinical Experience with aDown-Sized Active Can ImplantableCardioverier Defibrillator in 162 ConsecutivePatients

Treatment with an ICD is the first-line treatmentfor survivors of sudden cardiac death. More recently, evidence accumulates that prophylactic ICD therapy may be beneficial for selected subgroups of patients after myocardial infarction. Particularly for future studies on the value of prophylactic ICD therapy, downsized devices are needed to allow easy pectoral implantation with a single lead configuration and featuring extended memory capabilities.Accordingly, this study assesses the clinical performance of a downsized fourth-generation ICD in 162consecutive patients. All devices could be successfully implanted pectorally, in 96% with a single leadconfiguration with a low defibrillation threshold of 10.6 ± 5.2 J. During a 3-month follow-up, 26% of thepatients received ICD therapy. Twenty percent had appropriate therapy for ventricular fibrillation (n= 9) and VT (n = 23), which was effective in all cases. Of the 450 episodes of VT, 426 were terminated by an-titachycardia pacing. Fourteen patients (9%) had inappropriate ICD therapy mainly due to atrial fibrillation or sinus tachycardia, which could be reliably diagnosed by the ICD stored intracardiac electrograms.     

Initial Clinical Experience with a New Small Sized Third-Generation Implantable Cardioverter Defibrillator: Results of a Multicenter Study

This study reports the acute clinical experience with the new CPI VENTAK MINI: a small sized (68 cc), implantable cardioverter defibrillator (ICD) with 33 J stored energy. Implantation of the device was attempted in 113 patients (90 men, mean age 57 ± 16 years, 64 with coronary artery disease, mean left ventricular ejection fraction 41%) with ventricular tachycardia or ventricular fibrillation (VF). All 113 patients (100%) were ultimately implanted, 12% of them for ICD replacement. Transvenous lead implantation was accomplished in all 104 patients (100%) receiving new leads, 95% of them with a single lead configuration. The safety criteria for implantation (2 consecutive VF conversions at 15 J or 3 at 20 J. in both cases without failures to convert) were demonstrated in all but 7 patients (6%). In 6 of these, safety criteria were not fully assessed while in the last patient defibriliation efficacy was not determined. Of the 104 patients with new leads, 90% underwent pectoral implantation. Of the 9 patients (9%) abdominally implanted, only 4 (4%) (3 children) were judged small sized for pectoral implant. At predischarge testing, reliable VF detection and conversion were noted in 96 of 97 patients tested. There was no perioperative mortality. At a 3.6 ± 1.3 months follow-up, 34% of the patients had a spontaneous arrhythmic event, and 24% of the patients received shocks. Clinically inappropriate therapies occurred in 8% of the episodes in which any kind of therapy was delivered. This study demonstrates the short-term clinical efficacy and safety of the new device, and that pectoral implantation can be performed in the large majority of patients.     

Comparison of Subxiphoid and Traditional Approaches for ICD Implantation

We compared clinical and electrophysiological data in 18 patients undergoing ICD implantation via a traditional (median sternotomy or left lateral thoracotomy) with 29 patients with a Subxiphoid approach. Both groups were similar in terms of age, sex, left ventricular ejection fraction, presence of coronary artery disease, and clinical indication for the device. Fifteen patients (83%) with the traditional approach had previous cardiac surgery compared with 6 patients (21%) who had a subxiphoid approach (P < 0.001). Both groups had similar patch R wave and sensing R wave measurements. Patients with the traditional approach had a lower energy for defibrillation than patients with a subxiphoid approach (13.6 ± 6.8 J vs 17.9 ± 4.1) (P < 0.05). Postoperative hospital days were fewer in the subxiphoid group compared with the traditional approaches (9.8 ± 5.3 vs 13.7 ± 7.5 days) but the differences did not reach statistical significance, possibly due to small numbers. The subxiphoid approach appears to be a reasonable alternative approach to the traditional approach in selected patients undergoing ICD implantation.     

Comparison of Electrical Characteristics Between a Steroid-Eluting Single-Pass VDD Lead and a Standard Steroid-Eluting Ventricular Lead

Compared to regular ventricular leads, single-pass VDD leads have two additional floating electrodes proximal to the ventricular tip, which enables them to detect atrial signals. Because of the latter, VDD leads are thicker than ventricular leads, which could affect ventricular pacing. The purpose of the present study was to compare ventricular pacing of a steroid-eluting single-pass VDD lead (CapSure VDD, Medtronic; n = 107) with the same steroid-eluting regular lead (CapSure SP, Medtronic; n = 39) implanted in the ventricle; both leads were connected to the same types of pacemakers. At implantation, pacing thresholds were measured at 0.5-ms pulse duration and impedance by means with the PSA. At discharge, as well as after 1 and 3 months, pulse duration thresholds were determined at 2.5 V pulse amplitude and impedance by telemetry. At implantation, pacing thresholds and impedance were not different in the VDD (0.38 ± 0.16 V; 691 ± 122 Ω) and ventricular lead group (0.44 ± 0.17 V; 648 ± 150 Ω). During follow-ups, no differences in pulse duration threshold were detected between the two groups neither at discharge (VDD = 0.05 ± 0.03 ms; ventricular 0.05 ± 0.02 ms), nor after 1 (VDD = 0.05 ± 0.02 ms; ventricular 0.08 ± 0.07 ms) and 3 months (VDD = 0.06 ± 0.03 ms; ventricular 0.09 ± 0.10 ms). There were also no significant differences for impedance at discharge (VDD = 675 ± 113 Ω; ventricular = 594 ± 113 Ω), after 1 (VDD = 678 ± 131 Ω,; ventricular = 627 ± 112 Ω) and 3 months (VDD = 652 ± 99 Ω; ventricular = 628 ± 105 Ω). Pacing thresholds and impedance were neither significantly different at implantation nor during follow-ups between patients with steroid-eluting VDD leads and patients with an equivalent ventricular lead indicating that the thicker VDD lead does not affect ventricular pacing.     

Time to First Shock in Implantable Cardioverter Defibrillator (ICD) Patients with Chagas Cardiomyopathy

The time to first ICD shock has been extensively studied in patients with coronary artery disease (CAD). However, there are no published data on ICD shocks in patients with Chagas cardiomyopathy (ChC). The occurrence of the first appropriate ICD shock during the first 6 months of follow-up in 20 patients with ChC (group 1) and 35 CAD patients (group 2) was analyzed retrospectively. All patients had received a third-generation pectoral ICD for ventricular tachycardia or fibrillation (VT/VF). Indications for ICD implantation were refractoriness to drug therapy or noninducibility of VT/VF at EPS in cardiac arrest survivors. Results: The mean age, left ventricular ejection fraction (LVEF), and sex in groups I and II were 57.4 ± 7 years versus 64 ± 9 (P < 0.01), 30.9%± 10% versus 32.9%± 10% (P = NS), and 10 men versus 31 women (P < 0.005), respectively. Six months after ICD implantation, 85% (17/20) group I patients received appropriate ICD shocks versus 51 % (18/35) in group 2, a statistically significant difference (P < 0.02, RR: 1.65, OR: 5.35). Conclusions: The incidence of appropriate ICD shocks within the first 6 months postimplantation was significantly higher in ChC patients than in CAD patients. ChC patients were younger and more often women than CAD patients.     

Short-and Long-Term Performance of a Tripolar Down-Sized Single Lead for Implantable Cardioverter Defibrillator Treatment: A Randomized Prospective European Multicenter Study

A new, thinner (10 Fr) and more flexible, single-pass transvenous endocardial ICD lead, Endotak DSP, was compared with a conventional lead, Endotak C, as a control in a prospective randomized multicenter study in combination with a nonactive can ICD. A total of 123 patients were enrolled, 55 of whom received a down-sized DSP lead. Lead-alone configuration was successfully implanted in 95% of the DSP patients vs 88% in the control group. The mean defibrillation threshold (DFT) was determined by means of a step-down protocol, and was identical in the two groups, 10.5 ± 4.8 J in the DSP group versus 10.5 ± 4.8 J in the control group. At implantation, the DSP mean pacing threshold was lower, 0.51 ± 0.18 V versus 0.62 ± 0.35 V (p < 0.05) in the control group, and the mean pacing impedance higher, 594 ± 110 Ω vs 523 ± 135 Ω (p < 0.05). During the follow-up period, the statistically significant difference in thresholds disappeared, while the difference in impedance remained. Tachyarrhythmia treatment by shock or antitachycardia pacing (ATP) was delivered in 53% and 41%, respectively, of the patients with a 100% success rate. In the DSP group, all 28 episodes of polymorphic ventricular tachycardia or ventricular fibrillation were converted by the first shock as compared to 57 of 69 episodes (83%) in the control group (p < 0.05). Monomorphic ventricular tachycardias were terminated by ATP alone in 96% versus 94%. Lead related problems were minor and observed in 5% and 7%, respectively. In summary, both leads were safe and efficacious in the detection and treatment of ventricular tachyarrhythmias. There were no differences between the DSP and control groups regarding short- or long-term lead related complications.     

Patient Discomfort Following Pectoral Defibrillator Implantation Using Conscious Sedation

Background: The miniaturization of implantable cardioverter defibrillators (ICDs) has made pectoral implantation possible. However, postoperative pain following the procedure has not been systematically studied. The aim of the current study was to prospectively assess patient discomfort and identify factors influencing pain perception during follow-up. Methods: Pain related to device implantation was quantified in 21 consecutive patients (age, 61 ± 11 years; 17 men and 21 women; 16 of 21 had coronary artery disease; left ventricular ejection fraction, 32%± 15%) undergoing pectoral ICD implantation with conscious sedation (fentanyl 118 ± 72 μg, midazolam 14 ± 9 mg). Patients completed the Visual Analogue Scale (VAS, 0–100) and the McGill Pain Questionnaire 24 hours and 1 month postoperatively. Regression analysis was used to define clinical and procedure related variables affecting patient discomfort and frequency of postoperative analgesic use. Results: The mean VAS score was 34 ± 20 24 hours postoperatively. A single (4.8%) patient described postoperative pain as severe. Pain was reported to be moderate by 10 (47.6%) patients and mild by 10 (47.6%) patients. Intraoperative fentanyl requirement was a predictor of postoperative pain (R = 0.51, P = 0.036), and procedural duration was a strong predictor of postoperative analgesic use (R = 0.75, P < 0.001). Pain at 1 month decreased to a VAS score of 19 ± 18 (P = 0.002 vs 24 hours) and was rated to be severe, moderate, and mild by 1, 3, and 17 patients, respectively. Late pain was related to a VAS score at 24 hours (R = 0.67, P = 0.004). Conclusions: (1) Pectoral ICD implantation using conscious sedation is well tolerated. (2) Postoperative discomfort correlates with longer procedural times and larger intraoperative narcotic requirements.     

Initial Clinical Experience with a Dual Lead Endocardial Defibrillation System with Atrial Pace/Sense Capability

Ninety-three patients underwent implants of the Telectronics Model 4211 ICD attached to the Enguard PFX endocardial defibrillation lead system. Eighty-one males and 12 females ranging in age from 25–85 years (mean= 64). Coronary disease was the substrate in the majority (88%); mean left ventricular ejection fraction was 30%. VT was present in 66%, VF in 22%, and both in7%, Three lead configurations were used in the study: ventriculo-atrial (Ul, 86%); bidirectional (B2,12%); and ventricular to patch (U2, 2%). Mean RVpacing thresholds were 0.46 V preand 0.54 Vposttesting, with no significant differences between the two. Mean R wave voltage was 11.05 mVpreand 11.72 mV posttesting, also not significantly different. A subgroup of 13 patients had mean atrial pacing thresholds of 0.59 V at 0.5 msec pulse width, with mean P waves of 4.01 mV. Mean defibrillation threshold for the entire group was 10.6 J using biphasic waveforms. Defibrillation thresholds by configuration were: 399 V (U1);475 V(U2);and350 V(B2). All patients but one had thresholds ±550 V in at least one configuration. The 4211/Enguard system was implanted without (86%) or with (14%) a subcutaneous patch electrode. Early postoperative findings related to the ICD system include: one device circuit failure, one early lead dislodgement, and one pacing exit block. There were five patient deaths during the follow-up period of 8.5 months: three cardiac nonsudden and two noncardiac. These data suggest that the 4211/Enguard defibrillation system can be successfully implanted in the majority of patients in need of such therapy.     

Ventricular Arrhythmia Inducibility Predicts Subsequent ICD Activation in Nonischemic Cardiomyopathy Patients: A DEFINITE Substudy

Objectives: We evaluated whether electrophysiologic (EP) inducibility predicts the subsequent occurrence of spontaneous ventricular tachycardia (VT) or ventricular fibrillation (VF) in the Defibrillators in Nonischemic Cardiomyopathy Treatment Evaluation (DEFINITE) trial.
Background: Inducibility of ventricular arrhythmias has been widely used as a risk marker to select implantable cardioverter defibrillator (ICD) candidates, but is believed not to be predictive in nonischemic cardiomyopathy patients.
Methods: In DEFINITE, patients randomized to the ICD arm, but not the conventional arm, underwent noninvasive EP testing via the ICD shortly after ICD implantation using up to three extrastimuli at three cycle lengths plus burst pacing. Inducibility was defined as monomorphic or polymorphic VT or VF lasting 15 seconds. Patients were followed for a median of 29 ± 14 months (interquartile range = 2–41). An independent committee, blinded to inducibility status, characterized the rhythm triggering ICD shocks.
Results: Inducibility, found in 29 of 204 patients (VT in 13, VF in 16), was associated with diabetes (41.4% vs 20.6%, P = 0.014) and a slightly higher ejection fraction (23.2 ± 5.9 vs 20.5 ± 5.7, P = 0.021). In follow-up, 34.5% of the inducible group (10 of 29) experienced ICD therapy for VT or VF or arrhythmic death versus 12.0% (21 of 175) noninducible patients (hazard ratio = 2.60, P = 0.014).
Conclusions: In DEFINITE patients, inducibility of either VT or VF was associated with an increased likelihood of subsequent ICD therapy for VT or VF, and should be one factor considered in risk stratifying nonischemic cardiomyopathy patients.     

Biphasic Defibrillation Using a Single Capacitor with Large Capacitance: Reduction of Peak Voltages and ICD Device Size

The volume of current implantable cardioverter defibrillators (ICD) is not convenient for pectoral implantation. One way to reduce the size of the pulse generator is to find a more effective defibrillation pulse waveform generated from smaller volume capacitors. In a prospective randomized crossover study we compared the step-down defibrillation threshold (DFT) of a standard biphasic waveform (STD), delivered by two 250-μF capacitors connected in series with an 80% tilt, to an experimental biphasic waveform delivered by a single 450μF capacitor with a 60% tilt. The experimental waveform delivered the same energy with a lower peak voltage and a longer duration (LVLDj. Intraopera-tively, in 25 patients receiving endocardial (n = 12) or endocardial-subcutaneous array (n = 13) defibrillation leads, the DFT was determined for both waveforms. Energy requirements did not differ at DFT for the STD and LVLD waveforms with the low impedance (32 ± 4Ω) endocardial-subcutaneous array defibrillation lead system (6.4 ± 4.4 J and 5.9 ± 4.2 J, respectively) or increased slightly (P - 0.06) with the higher impedance (42 ± 4 Ω) endocardial lead system (10.4 ± 4.6 J and 12.7 ± 5.7 /. respectively), However, the voltage needed at DFT was one-third lower with the LVLD waveform than with the STD waveform for both lead systems (256 ± 85 V vs 154 ± 53 V and 348 ± 76 V vs 232 ± 54 V, respectively). Thus, a single capacitor with a large capacitance can generate a defibrillation pulse with a substantial lower peak voltage requirement without significantly increasing the energy requirements. The volume reduction in using a single capacitor can decrease ICD device size.     

Long-term Stability of Endocardial Left Ventricular Pacing Leads Placed via the Coronary Sinus

Background: Left ventricular endocardial pacing leads placed via the coronary sinus (CS) are increasingly implanted to achieve cardiac resynchronization therapy (CRT); however, the long-term stability of these leads is unknown. We sought to determine the implant success and long-term stability of CS leads in our single center experience.
Methods: All consecutive patients who underwent CRT via implantation of the CS lead between January 1999 and December 2005 were included. Pacing thresholds at implant and during long-term follow-up were reviewed and the rate of acute (within 24 hours of implant) and chronic (>24 hours) lead failure was determined.
Results: A total of 512 patients (mean age 68 ± 12 years; 409 [80%] male) underwent CRT device implantation and were included. The CS lead implantation was successful on the initial implantation in 487 patients (95%) and subsequently successful in six patients (24%) in whom initial attempts were unsuccessful. Acute lead failure occurred in 25 patients (5.1%) and was most commonly due to persistent extra-cardiac stimulation. The rate of chronic lead failure was 4% in the first year and remained stable during long-term follow-up. The CS lead pacing thresholds remained stable with only minimal increase (1.42 ± 0.85 V/0.42 ± 0.25 ms vs 1.51 ± 1.05 V/0.47 ± 0.29 ms; P = 0.04).
Conclusions: Placement of a left ventricular pacing lead via the CS is feasible and safe in the vast majority of patients. Once placed, the CS leads remain stable with excellent pacing thresholds over the longer term.     

Cost and Length of Hospital Stay: Comparisons Between Nonthoracotomy and Epicardial Techniques in Patients Receiving Implantable Cardioverter Defibrillators

Twenty-five patients with implantable Cardioverter defibrillators (ICDs) implanted intrathoracically (group I) were compared with 25 patients who underwent implant using the nonthoracotomy approach (group II). AH systems were implanted by the same medical team, in the same high volume implanting center. Indications for implantation were comparable in both groups. Patient characteristics were not statistically different with the exception of age fee-group I vs 71-group II; P < 0.05). Although left ventricular ejection fractions appeared to differ (32% vs 37%, respectively), this difference was not statistically significant (P = 0.06). ICD models used in group I were: Ventritex Cadence (16), Telectronics Guardian 4211 (2), Medtronic PCD (7); in group II they were: Ventritex Cadence (15), Guardian 4211 (2), and CPI 1600 (1). Total length of hospital stay was 16 ± 6 days for group I versus 12 ± 5 for group II (P < 0.05). Number of postoperative days in an intensive care unit was 3.2 ± 2.8 for group I versus 0.5 ± 0.6 for group II (P < 0.0001). Postoperative length of stay was 8.2 ± 3.1 for group I versus 5.7 ± 4.4 for group II (P < 0.001). Mean total hospital charges for the entire length of stay were $72,918 ±$26,770 in group I versus $55,031 ±$42,870 in group II, representing a mean reduction of 21 % in global costs for group II patients. These data confirm that nonthoracotomy ICD implantation in an experienced center is associated with significantly shorter hospital stays, a virtual elimination of the need for postoperative intensive care, and globally lower total hospital costs. In addition, the presence of a statistically older population in group II does not negate these beneficial effects.     

Radiofrequency Catheter Ablation of Ventricular Tachycardia Following Implantation of an Automatic Cardioverter Defibrillator

The present study reports on the complementary role of two nonpharmacological options of antiarrhythmic therapy. Background: Catheter ablation, antitachycardia surgery, and the implanfahie cardioverter de/ibrillator (ICD)have become important tools in the management of ventricuiar tachyarrhythmias. However, the emergence of ventricuiar tachyarrhythmias after implantation of an ICD is possihie because the arrhythmogenic suhstrate is not affected. Patients and Methods:Six of 180 patients developed frequent episodes of monomorphic ventricular tachycardia (n = 2) or incessant ventricular tachycardia (n = 4) following implantation of an ICD and underwent radio/requency (RF)catheter ablation. Catheter ablation was performed using a HF generator HAT 200. Energy was delivered between a 4-mm tip electrode of the ahiation catheter and a patch electrode. Results: Catheter ablation was done 6.8 ± 5 months following ICD implantation; 6 ± 2.2 RF impulses were delivered at the site of origin of ventricuiar tachycardia chararcterized by early endocardial activation during ventricular tachycardia, identical pace mapping and long latency between stimulus, and QRS-complex in five patients. New bundle branch reentry was the underlying mechanism of ventricular tachycardia in one patient. RF catheter ablation resulted in termination o/ incessant ventricular tachycardia. Immediately postabiation, the documented ventricular tachycardia was rendered noninducible in all patients. No ICD malfunctions have been observed. One patient died due to heart failure 24 hours after successful ablation of the incessant ventricular tachycardia. During a follow-up of 5–19 months, episodes of ventricular tachycardia recurred in four patients. All episodes could be controlled by the ICD without frequent cardioversions. Conclusion: RF catheter ablation is o complementary therapeutic option in case of frequent or incessant ventricular tachycardia after ICD implantation.