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[14-year experience with implantable cardioverter/defibrillators: determination of prognosis and discharge behavior]
1Medizinische Klinik und Poliklinik B, Evangelisches Krankenhaus Düsseldorf.
Insights
Implantable cardioverter-defibrillators (ICDs) improve survival for high-risk patients. Left ventricular function and heart failure severity significantly impact ICD effectiveness and prognosis over time.
Area of Science:
- Cardiology
- Medical Devices
- Electrophysiology
Background:
- Implantable cardioverter-defibrillators (ICDs) are the standard treatment for life-threatening ventricular arrhythmias.
- ICD therapy offers proven survival benefits over drug therapy for patients with aborted sudden cardiac death (SCD) and unstable ventricular tachycardia.
- ICD use is increasing for primary prevention of SCD in high-risk individuals.
Purpose of the Study:
- To evaluate the long-term survival rates and prognosis in patients treated with ICDs.
- To identify factors influencing ICD discharge rates and patient outcomes.
- To compare ICD effectiveness across different patient subgroups based on cardiac condition and severity.
Main Methods:
- Analysis of long-term follow-up data from 274 consecutive patients implanted with ICDs between 1984 and 1998.
- Assessment of survival probability and freedom from ICD events (shocks or antitachycardic pacing).
- Subgroup analysis based on New York Heart Association (NYHA) functional class, left ventricular ejection fraction, and underlying cardiac disease.
Main Results:
- Overall 10- and 14-year survival probabilities were 84% and 65%, respectively.
- Prognosis varied significantly by NYHA class: 5-year survival was 94% for NYHA class I/II versus 63% for NYHA class III/IV.
- Left ventricular ejection fraction, age, and basic cardiac disease were key determinants of prognosis and ICD discharge rates, while electrophysiological testing results were not predictive.
Conclusions:
- Left ventricular function, age, and underlying cardiac disease are significant predictors of prognosis and ICD discharge rates.
- The relative survival benefit of ICDs diminishes over time for patients with worse left ventricular function (NYHA class III/IV).
- Patients with aborted SCD and preserved left ventricular function experience fewer ICD discharges and achieve near-normal life expectancy.
Background:
The treatment of life threatening ventricular arrhythmias with implantable cardioverter/defibrillators (ICD) has become the therapy of choice; the survival benefit of ICD treatment compared to drug therapy in patients with aborted sudden cardiac death (SCD) and hemodynamically unstable ventricular tachycardia has been proven. In addition for the primary prevention of SCD in high risk patients, ICD therapy is gaining growing acceptance.
Patients And Methods:
We analyzed the long-term follow-up of 274 consecutive patients (211 male, 63 female, age 59 +/- 12 years, left ventricular ejection fraction 39 +/- 15%) provided with an ICD between 1984 and 1998. The aim of the study was to ascertain the survival rate in different subgroups and to discover determining factors of ICD discharge and prognosis.
Results:
Long-term survival probability at 10 resp. 14 years was 84 resp. 65% for the total collective, and the freedom of event probability (neither shocks nor antitachycardiac pacing from the ICD) to 28% each. The risk to die from SCD was below 3% over time. The most pronounced differences regarding prognosis ensued from dividing the collective into heart insufficiency stages. Thus in NYHA class I and II versus III and IV, the cumulative event rate was 61% vs 82% at 5 years, and survival rate amounted to 94 vs 63% at 5 years and 87% vs 30% at 14 years (p < 0.001). Calculating the relative benefit of ICD therapy survival benefit provided by the ICD was shown to decrease significantly after 5 years for patients in NYHA class III/IV, while it increased progressively for patients in NYHA class I/II up to 10 years. Additional determinants of prognosis and ICD discharge rate were identified left ventricular ejection fraction, age and tendency for the basic cardiac disease, however neither the result of electrophysiological testing nor the results of non-invasive risk stratification. In patients with ischemic heart disease, revascularization procedures improved prognosis only in tendency, while the effect of ICD therapy was significant. In patients with the non-obstructive form of hypertrophic cardiomyopathy ICD, discharges occurred in about 50% of patients; in contrast patients with surgical myectomy for obstructive cardiomyopathy showed no events during follow-up. In patients with chronic inflammatory heart disease and normal left ventricular function (LVF), a very low event rate was expected if patients were treated by immunosuppressive drugs. Patients with dilated cardiomyopathy did not differ from patients with ischemic heart disease with respect to prognosis and ICD discharge rate.
Conclusion:
Significant determinants of prognosis and ICD discharge rate are left ventricular function, age and with limitations the basic cardiac disease. In contrast to patients with better LVF relative survival benefit decreases significantly after 5 years in patients with a worse LVF. Patients with aborted SCD and preserved LVF experience half the ICD discharges compared to patients with poor LVF and gain at the same time a normalization of life expectancy. Causative treatment of the basic disease has an impact on the overall prognosis and event rate, but should in general not influence the decision for IDC implantation in high risk patients.