Cardioverter defibrillator therapy as a bridge to heart transplantation

[Prevention of sudden death in patients awaiting heart transplantation]

Sudden death, unexpectedly alters outcome in many patients awaiting heart transplantation. The prevention of sudden death in these patients has been the focus of intensive research to achieve a larger number of patients who finally receive transplants. Recent advances in the medical treatment of heart failure, have reduced mortality and in particular, that caused by sudden death. Nonetheless sudden death remains a frequent cause of mortality in patients awaiting cardiac transplantation. The recognition of patients at very high risk for sudden death is relatively easy, but most patients who suffer sudden death while awaiting cardiac transplantation, are not among those initially included in the overall high risk category. The betablockers, when patients are able to use them, can reduce sudden and total mortality. Class I antiarrhythmic drugs should not be used in patients with cardiac failure. Amiodarone does not increase mortality and may have a beneficial effect in some patients, but its efficacy is lower than that of the implantable defibrillator and its widespread use is not justified. The implantable defibrilator is the reference treatment to reduce sudden death in selected patients, awaiting transplantation.

Spatial features in body surface potential maps of patients with ventricular tachyarrhythmias with or without coronary artery disease

Body surface potential maps (BSPM) from patients with coronary artery disease or no structural heart disease were analyzed with respect to their spatial features and QT/QTc dispersion in order to determine whether BSPM allows identification of patients with ventricular fibrillation. QRST integral maps and QT/QTc dispersion were acquired from simultaneous recordings of 62 ECG leads during sinus rhythm in patients with idiopathic ventricular fibrillation (n=13), ventricular fibrillation and coronary artery disease (n=22), coronary artery disease without ventricular fibrillation (n=21) and healthy controls (n=18). The Karhunen-Loeve transformation was applied to reduce the dimensionality of the data matrix of the QRST map to eight coefficients. Linear discriminant analysis allowed discrimination between idiopathic ventricular fibrillation patients and controls with high sensitivity (85%) and specificity (89%). However, discrimination between coronary artery disease patients with or without ventricular fibrillation was poor (68% and 67%, respectively). QTc dispersion calculated from BSPM was longer in idiopathic ventricular fibrillation patients than in controls (99+/-30 ms vs 70+/-14 ms, P=0.009) in contrast to QTc dispersion taken from 12-lead ECG (53+/-21 ms vs. 47+/-12 ms, P=n.s.). No significant difference was noted for coronary artery disease patients with or without ventricular fibrillation. In conclusion, repolarization disturbances detected by BSPM allow identification of ventricular fibrillation patients without structural heart disease. However, our results do not suggest a major impact of QT/QTc dispersion or QRST integral mapping for identification of ventricular fibrillation patients with coronary artery disease.

Combining nonpharmacologic therapies for advanced heart failure: the Münster experience with the assist device-defibrillator combination

Implantable cardioverter defibrillators (ICDs) and ventricular assist devices (VADs) have been used as a bridge to cardiac transplantation. In selected patients, the combined implantation may be required. This study was motivated by a case of a 33-year-old female patient with giant cell myocarditis who died of ventricular tachyarrhythmias after having been placed on a VAD with which she had been treated on an out-of-hospital basis for a prolonged period of time. A subsequent retrospective analysis of our data showed that, of 73 patients who had to be bridged mechanically (54 Novacor, 12 TCI Heartmate, 4 Thoratec, 3 Medos) in our institution between 1993 and 1998, 10 patients had undergone defibrillator implantation either before (n = 8) or after (n = 2) implantation of a VAD. The cases are presented, and the feasibility of the combination therapy discussed.

What risk should justify implantable cardioverter defibrillator therapy?

Implantable cardioverter defibrillators (ICDs) were developed to prevent sudden cardiac death in patients with ventricular tachycardia (VT) or ventricular fibrillation (VF). Their safety and efficacy have been proved in multiple retrospective and prospective studies. Many of the published trials were directed at secondary prevention for patients who had already had a sudden cardiac death or a sustained VT. For primary prevention, the information available is limited, as only 2 trials have yet been published. Ongoing trials will probably allow us to broaden the indications for prophylactic ICD implantation. Justification of the risk will have to be evaluated against complexity of the implant, the latter including not only cost but quality of life and morbidity associated with an ICD. However, our efforts still have to be directed to improve risk stratification and to decrease the complexity of the procedure.

The implantable cardioverter defibrillator as a "bridge to transplant": a viable clinical strategy?

Heart transplantation is an accepted therapeutic option for patients with end-stage heart disease. However, because the availability of heart donors fails to keep pace with the growing demand, increasing numbers of potential recipients are placed on the waiting list, resulting in longer waiting times. About 20% of patients die while awaiting heart transplantation. The majority die from progressive pump failure (46%), whereas about 30% of all deaths occur suddenly. Monitored terminal cardiac electrical activity in patients dying while awaiting transplantation reveals that bradyarrhythmias and/or electromechanical dissociation are involved in 68% of cases and ventricular tachyarrhythmias in 32% of cases. Patients with a history of aborted cardiac arrest are at highest risk for recurrent malignant arrhythmias. The implantable cardioverter defibrillator (ICD) is the most effective therapy for preventing sudden cardiac death from ventricular tachyarrhythmias. Pooled data from a total of 75 sudden death survivors listed for cardiac transplantation demonstrate that ICD therapy can be applied with low mortality, low morbidity, and high efficacy, with up to 94% of the patients receiving appropriate shocks during the waiting period. However, there is considerable concern that this early survival benefit conferred by the ICD may be nullified by the competing risk of death due to terminal pump failure, as the waiting list and waiting time to transplantation lengthens. In advanced heart failure, risk stratification for sudden tachyarrhythmic death is only of limited value. Therefore, although sudden tachyarrhythmic death appears to constitute only a minor fraction of total cardiac death in patients awaiting heart transplantation, prophylactic ICD implantation as on electronic bridge to transplant may be considered. To define conclusively the role of prophylactic ICD therapy in this setting, prospective randomized studies are needed.

Simultaneous use of an implanted defibrillator and ventricular assist device

A left ventricular assist device was placed as a bridge to cardiac transplantation in a 51-year-old man with cardiogenic shock. Placement of the left ventricular assist device occurred 5 years after implantation of an implantable cardioverter/defibrillator. The implantable cardioverter/defibrillator discharged appropriately during ventricular assist device support to terminate episodes of sustained ventricular tachycardia without causing malfunction of the ventricular assist device.

Long-term follow up of patients with implantable cardioverter-defibrillators and mild, moderate, or severe impairment of left ventricular function

OBJECTIVE

To determine whether patients with life threatening ventricular tachyarrhythmias, impaired left ventricular function, and severe heart failure will benefit from implantable cardioverter-defibrillator (ICD) treatment.

DESIGN

410 patients were followed up after ICD implant. Left ventricular function was assessed by the New York Heart Association (NYHA) functional class of heart failure: 50 patients (12%) were in NYHA I-II, 151 (37%) in NYHA II, 117 (29%) in NYHA II-III, and 92 (22%) in NYHA III. Epicardial ICD implantation was performed in 209 patients (51%) and 201 patients (49%) received non-thoracotomy ICDs.

RESULTS

Perioperatively, 12 patients (3%) died, more often after epicardial ICD implant (11/209 patients, 5%) than after transvenous implant (1/201 patients, < 1%) (P < 0.05). During a mean (SD) follow up of 28 (24) months (range < 1 to 114 months), 90 patients (23%) died: nine (2%) died from sudden arrhythmia; five (1%) also died suddenly but probably not from arrhythmic causes; 55 (14%) died from cardiac causes (congestive heart failure, myocardial reinfarction); 21 (5%) died from non-cardiac causes. The three year, five year, and seven year survival was 92-96% for arrhythmic mortality in NYHA class I, II and III, compared to a three year survival of 94% and a five year and seven year survival of 84% for patients in NYHA class II-III. 338 patients (82%) received ICD shocks (21 (SD 43) shocks per patient); patients in NYHA class II (83%), class II-III (84%), and class III (90%) received ICD discharges more often than those in class I-II (64%) (P < 0.05). The mean (SD) time interval between ICD implant and the first ICD shock was shorter in NYHA class II (16 (17) months), class II-III (19 (27) months), and class III (16 (19) months) than in class 0-I (22 (24) months) (P < 0.05).

CONCLUSIONS

Patients with mild, moderate, and severe left ventricular dysfunction benefit from ICD treatment and these patients survive for a considerable time after the first shock. Survival is influenced by the degree of left ventricular dysfunction; aggressive treatment of heart failure is necessary as well as ICD therapy.

[Defibrillator therapy 1997. Prerequisites--results--prospects]

BACKGROUND

The first human cardioverter defibrillator implant was performed in 1980. Since then, significant technological improvement has been performed and today, ICDs with multiple diagnostic and therapeutic features are available. We report on 541 patients who underwent ICD implantation between January 1984 and March 1997. Epicardial ICD implant was performed in 209 patients (39%) and 332 patients (61%) received transvenous ICDs.

PATIENTS AND RESULTS

Perioperative mortality was 2% (13 patients), significantly more frequent after epicardial (12/209 patients, 6%) than after transvenous implantation (1/332 patients) (p < 0.01). During a mean follow-up of 28 +/- 23 months, 104 patients died (20%), 15 of them (3%) suddenly. 8407 arrhythmic episodes were observed and terminated by antitachycardia pacing in 6655 (79%). Infections occurred in 13 patients (2%), electrode complications in 43 patients (8%) and inappropriate shocks in 84 patients (16%).

CONCLUSION

The ICD is an effective approach to treat patients with life-threatening ventricular tachyarrhythmias leading to a low incidence of sudden death. Today, there is a low operative risk and modern ICDs have multiple diagnostic and therapeutic features that allow individual ICD therapy.

Hospital readmission in patients treated with tiered-therapy implantable defibrillators

BACKGROUND

We wished to determine the incidence, reasons, costs, and predictors of cardiac-related hospital readmission in patients with tiered-therapy implantable defibrillators. Hospital readmission in patients with defibrillators reduces their quality of life and increases the cost associated with such therapy.

METHODS AND RESULTS

We retrospectively studied 65 consecutive local patients (median age, 67 years; median ejection fraction, 0.34) who underwent tiered-therapy defibrillator implantation at this institution. Patients were followed for a median of 19 months (interquartile range, 10 to 27 months). The cause, duration, costs, and predictors of cardiac-related rehospitalizations were analyzed. There were 76 cardiac admissions for 34 patients. The rate of cardiac-related hospital readmission was 0.72 per patient-year of follow-up. Arrhythmia-related admissions accounted for 43 of such admissions in 24 patients. Actuarial freedom from cardiac-related admissions was 0.57 and 0.40 at 1 and 2 years, respectively. The median length of stay for hospital readmissions was 5 days (interquartile range, 3 to 8 days). The median cost per admission was $5842 (interquartile range, $3549 to $12 170). The time to first readmission and the total rehospitalization time per year of follow-up were associated with a poor preimplant New York Heart Association functional class. Readmission for cardiac arrhythmias was not predicted by clinical parameters.

CONCLUSIONS

Rehospitalization for cardiac reasons is common in patients receiving implantable defibrillators and is responsible for substantial resource consumption. The need for readmission for arrhythmia-related reasons cannot be predicted by clinical parameters at the time of device implantation.