Transvenous cardioverter defibrillators: cost implications of a less invasive approach

Safety and potential cost savings of same-setting electrophysiologic testing and placement of transvenous implantable cardioverter-defibrillators

BACKGROUND

Separately, electrophysiologic study (EPS) and placement of a transvenous implantable cardioverter-defibrillator (ICD) can be performed safely in the majority of patients. The safety and potential cost savings of same-setting procedures have not been evaluated.

HYPOTHESIS

Electrophysiologic study and placement of transvenous ICDs can be performed safely in the same setting at reduced cost.

METHODS

In all. 160 (mean age 65 +/- 10 years, 75% men) and 41 (mean age 66 +/- 11 years, 73% men) consecutive patients who underwent same- versus separate-setting procedures, respectively, were prospectively evaluated.

RESULTS

The two groups had similar clinical characteristics and indications for EPS and ICD therapy. Complications occurred in eight patients (5.0%, 95% confidence interval [CI] 2.3-10.3) who had same-setting procedures (one hypotension during ICD testing, one pocket hematoma, two lead dislodgments, two pneumothoraces, one stroke, and one infection) and in two (4.9%, CI 0.60-16.5) who had separate-setting procedures (one pocket hematoma and one infection). There were no procedure-related deaths or long-term ICD-related complications in either group. The mean time from ICD implantation to hospital discharge was similar in the two groups (2.5 +/- 2.4 vs. 2.7 +/- 2.2 days, p = NS). The combined procedure cost was higher in patients who had separate-setting procedures ($12,403 +/- 1,386 vs. $10,242 +/- 2.256, p = < 0.001). who incurred an additional hospital cost of $2,121 +/- $2,125 for the waiting period (1.7 +/- 1.6 days) between EPS and ICD implantation.

CONCLUSIONS

In patients deemed candidates for ICD therapy based on EPS results, placement of transvenous defibrillators in the same setting as EPS is as safe as separate-setting procedures and, if adopted, could further reduce the cost of providing ICD therapy.

Robotic-enhanced biventricular resynchronization: an alternative to endovenous cardiac resynchronization therapy in chronic heart failure

BACKGROUND

Cardiac resynchronization therapy (CRT) by pacing the left and right ventricles is an emerging option for treatment of severe heart failure with ventricular conduction disturbances. Stimulation through a coronary vein is currently the technique of choice to achieve left ventricular (LV) pacing. Unfortunately, this approach carries significant limitations and drawbacks. Therefore we explored robotic-enhanced thoracoscopic implantation of an epicardial lead as an alternative technique to stimulate the LV in cardiac resynchronization therapy.

METHODS

A total of 15 patients were included in this study. Right (atrial and ventricular) leads were implanted classically through the left subclavian vein. Robotic-enhanced thoracoscopy was then performed to implant the LV epicardial lead.

RESULTS

Of the 15 patients, 13 underwent successful endoscopic robotic cardiac resynchronization therapy. Two patients underwent conversion to a small thoracotomy. No perioperative complication occurred in the patients who did not undergo conversion. Acute and chronic LV lead thresholds were satisfactory in all patients, improving over time. All were subjectively and objectively improved at 4 months. As compared with conventional methods, the procedural cost was not significantly affected.

CONCLUSIONS

Based on this feasibility study, we believe that robotic LV epicardial lead implantation is a valuable option to achieve biventricular resynchronization therapy. It allows for more reproducible acute thresholds for LV pacing and sensing than does the percutaneous approach; enables fine tuning of the LV lead position, thus potentially providing optimal hemodynamic benefit; and avoids the pitfalls and limitations of the endovenous approach. Therefore it deserves further prospective studies to assess its place in the therapeutic armamentarium against heart failure.

ICD therapy in the new millennium

Remarkable progress has been made in the 15 years since ICD therapy was approved for human use. The early "shock boxes" had almost no diagnostic capabilities and required thoracotomy for epicardial patch implantation with typical duration of hospitalization of about a week. Pulse-generator longevity was less than 2 years. Modern devices provide detailed information about the morphology and rate of electrocardiographic signals before, during, and after arrhythmia therapy. The down-sizing of pulse generators and improvements in lead design and shock waveforms allow the simplicity of defibrillator implantation to approach that of pacemakers, with defibrillation thresholds comparable with those initially observed with epicardial patches. Despite the marked reduction in size and increase in diagnostic capabilities, device longevity is now longer than 6 years. Routine outpatient ICD implantation is presently feasible and will increase in frequency if ongoing primary prevention trials prove beneficial. Further advances in lead technology and arrhythmia discrimination should increase the efficacy and reliability of therapy. Finally, devices have the capabilities to treat multiple problems in addition to life-threatening ventricular arrhythmias including atrial arrhythmias and congestive heart failure.

Replacing abdominally implanted defibrillators: effect of procedure setting on cost

Although most ICDs are currently placed using a pectoral approach, there exists a large population of patients with abdominally implanted ICDs who will require device replacement due to a depleted battery. The purpose of this study was to compare the cost, convalescence, and complication rate of replacing abdominally implanted ICDs in the OR versus the EP laboratory. Between August 1993 and September 1994, we prospectively enlisted nine consecutive patients who presented for their second ICD generator replacement and who had a prior generator replacement in the OR 3-4 years earlier. The mean age of the patients was 63 +/- 17 years and their mean ejection fraction was 37% +/- 15%. ICD replacement was performed in the EP laboratory and consisted of explanting the old device, electronic interrogation of the lead system, and confirmation of defibrillation thresholds prior to implanting a new device. Local anesthesia was provided by lidocaine infiltration and sedation was achieved with intravenous (i.v.) midazolam and fentanyl. Following the procedure, the patients were returned to an outpatient monitored setting for 4 hours and were then discharged. Comparisons of the health care charges for the same procedure performed in the two different settings revealed a significant reduction in physician fees (from $3,621 +/- $556 to $2,179 +/- $577, P < 0.05), in hospital charges (from $5,811 +/- $1,102 to $2,306 +/- 696, P < 0.05), and in total charges (from $9,431 +/- $1,375 to $4,541 +/- $1,010, P < 0.05), exclusive of ICD cost, when the procedure was performed on an outpatient basis in the EP laboratory. Inpatient days averaged 3.0 +/- 0.3 when the procedure was performed in the OR. On long-term follow-up there were no complications following abdominal ICD generator replacement in the OR (mean follow-up, 39 +/- 2 months) or in the EP laboratory (mean follow-up, 42 +/- 4 months). Thus, ICD replacements in the EP laboratory cost less than in the OR due to significantly lower physician fees, hospital charges, and a shorter postprocedural convalescence.

Prehospital discharge defibrillation testing in ICD recipients: a prospective study based on cost analysis

Prehospital discharge defibrillation testing is often performed to verify the function of newly implanted cardioverter defibrillators (ICDs). To determine whether elimination of predischarge testing could reduce costs without placing patients at additional risk, 31 patients were randomized in this prospective clinical evaluation to either receive or not receive a predischarge ICD defibrillation test. Expenses associated with postimplant care was the primary endpoint. All patients underwent induction of ventricular fibrillation after 6 months to evaluate ICD function. The groups were well matched in terms of patient characteristics, initial lead implant parameters, and defibrillation thresholds. Elimination of prehospital discharge testing resulted in a savings of $1,800/patient after 6 months, with no difference between groups in terms of ICD complication rates or unanticipated hospital admissions. Further studies are needed to better define the most appropriate time to assess defibrillation thresholds in the first year after implantation.

A comparison of pectoral and abdominal transvenous defibrillator implantation: analysis of costs and outcomes

Traditionally cardioverter-defibrillator implantation was performed by surgeons under general anesthesia. However, with advances in lead and pulse generator technology, the surgical implantation technique has been simplified and routine pectoral pulse generator placement without general anesthesia is now possible. To assess the economic benefit of pectoral implantation, we analyzed 43 consecutive initial transvenous defibrillator implantations. The patients were grouped according to whether the implant was abdominal by a surgeon in the operating room (n = 23) or pectoral by an electrophysiologist in a laboratory (n = 20). The duration of hospitalization was significantly longer in the operating room than in the laboratory group (8.1 +/- 3.4 vs 5.8 +/- 2.4 days, p = 0.01), which was due primarily to the postoperative stay which averaged 1.9 days longer. Total costs were $40,274 +/- 6,861 for the operating room cohort and $32,546 +/- 3,634 for the lab group (p < 0.001). This reduction was due to a 32% lowering of professional costs and an 18% lowering of facility costs. We conclude that pectoral defibrillator implantation is cost effective and results in significant reductions of hospital stay.

Short- and long-term performance of a tripolar down-sized single lead for implantable cardioverter defibrillator treatment: a randomized prospective European multicenter study. European Endotak DSP Investigator Group

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 omega vs 523 +/- 135 omega (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.

Subpectoral implantation of a cardioverter defibrillator under local anaesthesia

OBJECTIVE

To evaluate patient acceptability of submuscular implantation of a cardioverter defibrillator (ICD) under local anaesthesia with conscious sedation.

DESIGN

Retrospective review. Patient acceptability in the second half of the study was routinely assessed within 24 hours.

SETTING

Regional cardiac centre.

PATIENTS

45 consecutive patients with either aborted sudden death or haemodynamically unstable ventricular tachycardia were referred for ICD implantation.

INTERVENTIONS

A subpectoral implantation technique was employed. Twelve procedures were performed under general anaesthesia. Thirty three patients were sedated with midazolam and diamorphine, and local anaesthesia was achieved with bupivicaine. Ventricular fibrillation for defibrillation threshold testing was induced by alternating current, T wave shock, or ultrarapid burst pacing. Patients were contacted after the procedure to assess acceptability.

RESULTS

32 patients having implantation under local anaesthesia did not recall the surgical procedure. One patient described an awareness of "pushing" as the generator was positioned in the pocket. Seven patients said that the procedure was painless but recalled a test shock, four describing it as mildly uncomfortable. All 33 patients stated that they would be willing to have a second implant under local anaesthesia. Twelve patients who had the implant performed under general anaesthesia had no recollection of the procedure. Mean (SD) total procedure duration was significantly longer in those who had general anaesthesia (93 (16) v 67 (17) minutes; p = 0.0009).

CONCLUSIONS

Subpectoral implantation of ICDs may be performed safely with patient acceptability under local anaesthesia with conscious sedation.

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

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

Lead system optimization for transvenous defibrillation

Lead systems that include an active pectoral shell reduce defibrillation thresholds and permit transvenous defibrillation in nearly all patients. A further improvement in defibrillation efficacy is desirable to allow for smaller pulse generators with a reduced maximum output. Accordingly, the purpose of this study was to compare defibrillation thresholds with multiple transvenous lead systems including those with an active pectoral shell to determine which system would optimize defibrillation energy requirements. This prospective study was performed on 21 consecutive patients. Each subject was evaluated with 3 lead configurations with the order of testing randomized. The configurations were a dual coil transvenous lead (lead), the distal right ventricular coil and pectoral pulse generator shell (unipolar), and all 3 components (triad). The right ventricular coil was the cathode for the first phase of the biphasic defibrillation waveform. Delivered energy at defibrillation threshold was 11.2 +/- 3.4 J for the lead configuration, 10.1 +/- 5.2 J for the unipolar configuration, and 7.8 +/- 3.6 J for the triad configuration (p <0.01). Leading edge voltage (p <0.01) and shock impedance (p <0.001) were also decreased for the triad configuration compared with the lead or unipolar configurations, whereas peak current was minimized with the unipolar configuration (p <0.01). We conclude that the combination of a dual coil, transvenous lead and an active pectoral shell reduces defibrillation energy requirements compared with either the lead alone or unipolar configuration. Moreover, the defibrillation thresholds were < or =15 J in all patients using the triad lead system.

Biphasic waveforms prevent the chronic rise of defibrillation thresholds with a transvenous lead system

OBJECTIVES

The purpose of this study was to compare chronic changes in monophasic and biphasic defibrillation thresholds using a uniform transvenous lead system and testing protocol.

BACKGROUND

Defibrillation thresholds increase over time in patients with nonthoracotomy lead systems. This increase can result in an inadequate chronic defibrillation safety margin and could limit the safety of smaller pulse generators, which have a reduced maximal output. However, previous studies of the temporal changes of defibrillation thresholds evaluated complex lead systems or monophasic shock waveforms, neither of which are used with current technology.

METHODS

This study was a prospective, randomized assessment of the effects of shock waveforms on the changes of transvenous defibrillation thresholds over time. Paired monophasic and biphasic thresholds were measured both at implantation and at follow-up (250 +/- 105 days) in 24 consecutive patients who were not receiving antiarrhythmic drugs. The lead system was a dual-coil Endotak C lead, and reverse polarity shocks (distal coil = anode) were delivered.

RESULTS

Monophasic defibrillation thresholds increased from (mean +/- SD) 13.7 +/- 6.0 J to 16.8 +/- 6.7 J (p = 0.02), whereas biphasic thresholds were unchanged (10.4 +/- 4.3 J to 10.2 +/- 4.8 J, p = 0.86) in the same patients. Shock impedance chronically increased (47.0 omega to 50.5 omega, p = 0.02) and was unaffected by waveform.

CONCLUSIONS

These results indicate that biphasic shocks prevent the chronic increase in defibrillation thresholds with a transvenous lead system.

Clinical predictors of transvenous biphasic defibrillation thresholds

Transvenous lead systems have become routine for defibrillator placement. However, previous studies of clinical predictors of an adequate nonthoracotomy defibrillation threshold (DFT) evaluated monophasic waveforms or more complex lead systems, including subcutaneous patches. Accordingly, this study is a prospective evaluation of the predictors of an adequate biphasic DFT in 114 consecutive patients undergoing cardioverter-defibrillator implantation with a single transvenous lead. For each subject, 38 parameters were assessed, including standard demographic, electrocardiographic, echocardiographic, and radiographic measurements. An adequate DFT (< or =20 J) was achieved in 92% of patients. Multivariable analysis revealed 2 independent factors predictive of a high threshold: echocardiographic measurements of left ventricular dilation (odds ratio = 0.16, 95% confidence interval 0.05 to 0.53, p = 0.003) and body size (odds ratio = 0.36, 95% confidence interval 0.17 to 0.73; p = 0.005). No patient with a normal left ventricular end-diastolic dimension had a high DFT, whereas 14% (9 of 66) of those with left ventricular dilation had elevated thresholds. When the DFT cutoff was lowered to 15 J, as is necessary with some downsized pulse generators, an adequate threshold was observed in 84% of patients and the same 2 independent predictors of high thresholds were found. These results indicate that an adequate transvenous DFT can be predicted from simple clinical parameters.

Long-term follow-up of cardioverter-defibrillator implanted under conscious sedation in prepectoral subfascial position

BACKGROUND

Implantable cardioverter-defibrillators (ICDs) with intravenous electrode systems and downsized generators can be implanted by use of operative techniques similar to those employed for the insertion of permanent pacemakers. However, the safety, efficacy, and long-term follow-up of simplified implantation procedures remain to be evaluated. This report is a prospective long-term evaluation of nonselected patients receiving ICDs in the prepectoral subfascial position under conscious sedation.

METHODS AND RESULTS

Clinical characteristics of the 231 consecutive patients included a mean age of 63 years, a male-to-female ratio of 6.4, a left ventricular ejection fraction of 0.34, a mild-to-moderate heart failure in 91%, coronary artery disease in 84%, and a history of aborted sudden cardiac death or refractory ventricular tachyarrhythmias. Insertion of transvenous leads and prepectoral subfascial ICD implantation were performed in electrophysiology laboratories under local anesthesia and conscious sedation with intravenous midazolam and propofol. Successful implantation in all patients (operation time, 80 +/- 32 minutes, mean +/- SD) irrespective of body size and skin thickness was free of major complications, including need for emergency intubation. After surgery, 1 pocket hematoma, 1 seroma, and 1 pneumothorax required treatment. There was no operative or first-month mortality. During long-term follow-up averaging 453 +/- 296 days, six leads required repositioning, but pocket erosions or infections did not occur. First-year total survival was 97%.

CONCLUSIONS

Implantation under conscious sedation of ICDs in the prepectoral subfascial position is a safe and effective procedure with low operative and postoperative morbidity and favorable long-term outcome.

Chronic rise in monophasic defibrillation thresholds with a transvenous lead system

This study was a prospective evaluation of chronic changes of defibrillation thresholds in 31 clinically stable patients with a single transvenous lead, optimal shock polarity, and uniform testing protocol. At a mean follow-up of 273 +/- 146 days, defibrillation thresholds increased 26%, from 13.2 +/- 5.6 J to 17.1 +/- 6:0 J (p < 0.001), and shock impedance increased from 46.2 +/- 7.0 omega to 51.2 +/- 6.2 omega (p < 0.001).

Complications associated with pectoral implantation of cardioverter defibrillators. World-Wide Jewel Investigators

Pectoral placement of ICD pulse generators is now routine after downsizing of these devices. However, the safety of this approach is not well documented. The aim of this study was to evaluate complications in a large cohort of patients undergoing initial pectoral ICD implantation. The subjects for this study were 1,000 consecutive patients receiving a Medtronic Jewel ICD at 93 centers worldwide. Cumulative follow-up for all patients was 634 patient-years, with 64.9% of patients followed for 6 months or longer. The complications evaluated were erosion, pocket hematoma, seroma, wound infection, dehiscence, device migration, lead fracture, and dislodgment. In this series, 1.8% of patients experienced a pocket complication with only 3 (0.3%) erosions and 2 (0.2%) infections. Lead complications were observed in 2.1% of subjects, most commonly early dislodgment of the RV lead. We conclude that pectoral implantation of a downsized ICD system can be performed with a low rate of complications. However, careful attention to anchoring techniques and close early monitoring is important given the 1.7% rate of lead dislodgment that occurred primarily during the first month following implantation.

Cost savings with nonthoracotomy implantable cardioverter-defibrillators

We analyzed hospital and physician charges for 99 consecutive patients who underwent implantable cardioverter-defibrillator (ICD) implantation at our institution. Eighteen patients received an epicardial lead system and 81 were scheduled to receive a nonthoracotomy lead system, the generator being implanted either abdominally (n = 62) or pectorally (n = 19). The epicardial group had a significantly longer convalescent stay (11.6 +/- 2.5 days; mean +/- SEM) than the abdominal nonthoracotomy group, analyzed by intention to treat (4.6 +/- 0.5 days) or by treatment received (3.8 +/- 0.2 days; p <0.0001). Postoperative stay for the pectoral group was shorter still (2.9 +/- 0.4 days; p <0.033). Total charges for the epicardial group were $99,081 +/- $25,094, significantly higher than those for any of the nonthoracotomy groups (p <0.017). Total charges for the pectoral group were $44,128 +/- $2,465, significantly less than those for the abdominal nonthoracotomy group, analyzed by intention to treat ($59,961 +/- $1,369; p <0.05) or by treatment received ($56,679 +/- $635; p <0.05). Cost reductions in the nonthoracotomy groups were primarily due to decreased in-hospital convalescence period, lower surgeon and anesthesiologist fees, and lower procedure-day hospital charges in the pectoral group. The use of ICDs with nonthoracotomy leads can result in significantly shorter in-hospital convalescence and a reduction in total implant-related charges of 40% to 55%. The use of pectorally implanted ICDs results in further reduction in hospital stay and further cost reduction of 22% to 26%. The trend toward shorter convalescent stay without postimplant testing is likely to reduce further the overall costs of ICD implantation.

Complications associated with pectoral cardioverter-defibrillator implantation: comparison of subcutaneous and submuscular approaches. Worldwide Jewel Investigators

OBJECTIVES

The aim of this study was to compare complications in a large cohort of patients undergoing pectoral cardioverter-defibrillator implantation with a subcutaneous or submuscular approach.

BACKGROUND

Pectoral placement of implantable cardioverter-defibrillator (ICD) pulse generators is now routine because of downsizing of these devices. subcutaneous implantation has been advocated by some because it is a simple surgical procedure comparable to pacemaker insertion. Others have favored submuscular insertion to avoid wound complications. These surgical approaches have not been compared previously.

METHODS

The subjects for this study were 1,000 consecutive patients receiving a Medtronic Jewel ICD at 93 centers worldwide. Cumulative follow-up for all patients was 633.7 patient-years, with 64.9% of patients followed up for > or = 6 months. The complications evaluated were erosion, pocket hematoma, seroma, wound infection, dehiscence, device migration, lead fracture and dislodgment.

RESULTS

Subcutaneous implantation was performed in 604 patients and submuscular implantation in the remaining 396. The median procedural times were shorter for subcutaneous implantation (p = 0.014). In addition, the cumulative percentage of patients free from erosion was greater for subcutaneous implantations (p = 0.03, 100% vs. 99.1% at 6 months). However, lead dislodgment was more common with subcutaneous implantations (p = 0.019, 2.3% vs. 0.5% at 6 months) and occurred primarily during the first month postoperatively. Overall, there were no significant differences in cumulative freedom from complications between groups (4.1% vs. 2.5%, p = 0.1836).

CONCLUSIONS

Subcutaneous pectoral implantation of this ICD can be performed safely and has a low complication rate. This approach requires a simple surgical procedure and, compared with the submuscular approach, is associated with shorter procedure times and comparable overall complication rates. However, early follow-up is important in view of the increased lead dislodgment rate.

Transvenous defibrillation lead systems

The use of the implantable cardioverter defibrillator has grown dramatically over the past 10 years. One of the major advances in defibrillation technology is the development of transvenous lead systems. Compared with traditional epicardial lead systems, transvenous defibrillation leads reduce perioperative mortality, hospitalization, and costs. Transvenous lead systems provide reliable sensing of ventricular tachyarrhythmias, although redetection of ventricular fibrillation can be prolonged, especially with integrated lead systems. Both ramp and burst adaptive pacing are equally effective for the termination of ventricular tachycardia and are successful in up to 90% of spontaneous events. Defibrillation thresholds are higher with transvenous leads than with epicardial patches. These thresholds are reduced with the use of multiple transvenous leads, subcutaneous patches, or with reversing shock polarity. However, the development of biphasic waveforms has made the largest impact on the efficacy of these lead systems, allowing dual coil transvenous systems to be effective in about 90% of patients. Defibrillation efficacy is further enhanced and implantation simplified by the incorporation of an active pulse generator located in the left pectoral region. Active pectoral pulse generators with biphasic waveforms will be the primary lead system for new implants.

Implanted cardioverter-defibrillators are preferable to drugs as primary therapy in sustained ventricular tachyarrhythmias

The choice of initial therapy for patients with malignant ventricular tachyarrhythmias is examined based on clinical efficacy, patient safety, and cost. Antiarrhythmic drug therapy can be administered using a guided or empiric approach. Guided type-1 antiarrhythmic drug therapy has been associated with high arrhythmia recurrence rates (> 40% at 1 year) and moderate sudden death rates (10% at 1 year). Sotalol is associated with lower arrhythmia recurrence rates (20% at 1 year) that increase to 50% at 4 years. Beta-blocking agents have a limited role as stand-alone therapy in this condition. Empiric amiodarone therapy has sudden death-free survival rates of 82% at 2 years but has significantly poorer results in patients with ejection fractions < or = 40%. In contrast, implantable cardioverter-defibrillator (ICD) therapy has reported sudden death recurrence rates of 1% to 2% per year, with a cumulative index of 10% at 5 years. Total survival rate of ICD recipients ranges from 85% to 92% at 2 years. In patients with good left ventricular function, it approaches 90% at 5 years, whereas it is between 50% to 60% in patients with severe left ventricular dysfunction. Data from device memory indicate an absolute reduction in mortality rates with ICD intervention. Comparison of drug and device therapy has been performed in retrospective and prospective studies. Improved survival with device therapy is noted, particularly in patients with ejection fractions < or = 35% to 40% in retrospective studies. The results of two small prospective randomized trials also show significant survival advantage as compared with those for type-1C drugs and a mixed group of antiarrhythmic drugs. An initial strategy of ICD therapy was shown to be superior in the Netherlands Cooperative Study. The 30-day perioperative mortality rate of ICD therapy of 0.8% contrasts favorably with a 13% mortality rate in the ESVEM trial with antiarrhythmic drugs and a 3.5% mortality rate in the CASCADE study. Economic analyses show that drug therapy and device therapy are both within the range of other current cardiovascular therapies. An improving economic profile for device therapy has been observed with nonthoracotomy and pectoral implantation and direct use of ICD therapy because primary therapy shortens hospital stay and reduces costs. Based on available data, ICD therapy is preferable as initial therapy in patients with malignant ventricular tachyarrhythmias.