Who Should Get an ICD?
Mortality from cardiovascular disease continues to decline, but patients with coronary artery disease (CAD), left ventricular (LV) dysfunction, and asymptomatic ventricular arrhythmias remain at high risk for death. Although myocardial ischemia is responsible for many events, most sudden deaths and cardiac arrests among patients who have had a myocardial infarction (MI) result from reentrant ventricular tachycardia or fibrillation.
Despite advances in clinical research and medical technology, the management of cardiac arrhythmias and conduction disorders remains challenging. Sudden cardiac death is a major public health problem in the United States, responsible for 300,000 to 400,000 deaths annually. In 45% of CAD patients, sudden death is the first symptom and prevention of these deaths is among the highest priorities in cardiovascular research. Over the last 20 years, the implantable cardioverter defibrillator (ICD) (Figure 1) has repeatedly been shown to improve survival in patients with a history of spontaneous or inducible ventricular tachyarrhythmias (Figures 2, 3, 4).
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Figure 1.
Chest x-ray of a patient with a prior midline sternotomy for a myomectomy for medically refractory obstructive hypertrophic cardiomyopathy. Because of complete atrioventricular block and symptomatic nonsustained ventricular tachycardia, she had a dual chamber ICD placed in the left subpectoralis positions using the cephalic vein. The AP film (A) shows the ventricular lead placed at the RV apex with the atrial lead in the right atrium. The lateral film confirms the anterior position of both leads.
(Enlarge Image)
Figure 2.
Select Class I Recommendations of ICD Implantation*
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Figure 3.
Select Class IIa Recommendations of ICD Implantation*
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Figure 4.
Select Class III Recommendations of ICD Implantation
Patients with CAD and a depressed LV ejection fraction (LVEF) are at high risk for sudden cardiac death, even if they have no history of ventricular arrhythmias. In 1997, a trial was underway that was a major step forward both in delineating the indication for automatic ICD therapy and in guiding routine therapy for patients with impaired LV function as defined by a reduced LVEF. The second Multicenter Automatic Defibrillator Implantation Trial (MADIT II) enrolled patients with a prior MI and an LVEF of <30%, but did not include spontaneous or inducible ventricular arrhythmias in its entry criteria. On November 20, 2001, the trial was terminated early when it became apparent that mortality was 31% lower among patients treated with an ICD rather than conventional medical therapy (Figure 5). Subgroup analysis revealed internal consistency across a wide range of variables, including patient age, gender, baseline ejection fraction, heart functional class, QRS width, presence or absence of atrial fibrillation, and use of single- or dual-chamber pacing.
(Enlarge Image)
Figure 5.
Indications for ICD Therapy-Class III
Since this interview was first posted on Cardiosource in 2004, several additional trials have been published plus, in September 2006, new guidelines were released jointly by the American College of Cardiology, American Heart Association, and European Society of Cardiology. (Full text: http://www.cardiosource.com/guidelines/guidelines/arrhythmias/va_scd.pdf ) Figure 6 presents a summary of major ICD trials as presented in the new guidelines. Details of MADIT II, SCD-HeFT, DINAMIT, and DEFINITE trials appear following the interview with George J. Klein, MD, FACC. Also, in 2005, the Centers for Medicare & Medicaid Services (CMS) expanded national coverage for implantable automatic defibrillators by including new indications. To read the new transmittal, click here. (Accessed October 16, 2006.)
(Enlarge Image)
Figure 6.
Major Implantable Cardioverter Defibrillator (ICD) Trials
Despite their efficacy, ICDs are not a universally used technology. In addition to obvious economic issues, other factors complicate the decision-making process. This discussion delves into the debate regarding the appropriate use of ICDs in various patient populations.
Abstract
Mortality from cardiovascular disease continues to decline, but patients with coronary artery disease (CAD), left ventricular (LV) dysfunction, and asymptomatic ventricular arrhythmias remain at high risk for death. Although myocardial ischemia is responsible for many events, most sudden deaths and cardiac arrests among patients who have had a myocardial infarction (MI) result from reentrant ventricular tachycardia or fibrillation.
Despite advances in clinical research and medical technology, the management of cardiac arrhythmias and conduction disorders remains challenging. Sudden cardiac death is a major public health problem in the United States, responsible for 300,000 to 400,000 deaths annually. In 45% of CAD patients, sudden death is the first symptom and prevention of these deaths is among the highest priorities in cardiovascular research. Over the last 20 years, the implantable cardioverter defibrillator (ICD) (Figure 1) has repeatedly been shown to improve survival in patients with a history of spontaneous or inducible ventricular tachyarrhythmias (Figures 2, 3, 4).
(Enlarge Image)
Figure 1.
Chest x-ray of a patient with a prior midline sternotomy for a myomectomy for medically refractory obstructive hypertrophic cardiomyopathy. Because of complete atrioventricular block and symptomatic nonsustained ventricular tachycardia, she had a dual chamber ICD placed in the left subpectoralis positions using the cephalic vein. The AP film (A) shows the ventricular lead placed at the RV apex with the atrial lead in the right atrium. The lateral film confirms the anterior position of both leads.
(Enlarge Image)
Figure 2.
Select Class I Recommendations of ICD Implantation*
(Enlarge Image)
Figure 3.
Select Class IIa Recommendations of ICD Implantation*
(Enlarge Image)
Figure 4.
Select Class III Recommendations of ICD Implantation
Patients with CAD and a depressed LV ejection fraction (LVEF) are at high risk for sudden cardiac death, even if they have no history of ventricular arrhythmias. In 1997, a trial was underway that was a major step forward both in delineating the indication for automatic ICD therapy and in guiding routine therapy for patients with impaired LV function as defined by a reduced LVEF. The second Multicenter Automatic Defibrillator Implantation Trial (MADIT II) enrolled patients with a prior MI and an LVEF of <30%, but did not include spontaneous or inducible ventricular arrhythmias in its entry criteria. On November 20, 2001, the trial was terminated early when it became apparent that mortality was 31% lower among patients treated with an ICD rather than conventional medical therapy (Figure 5). Subgroup analysis revealed internal consistency across a wide range of variables, including patient age, gender, baseline ejection fraction, heart functional class, QRS width, presence or absence of atrial fibrillation, and use of single- or dual-chamber pacing.
(Enlarge Image)
Figure 5.
Indications for ICD Therapy-Class III
Since this interview was first posted on Cardiosource in 2004, several additional trials have been published plus, in September 2006, new guidelines were released jointly by the American College of Cardiology, American Heart Association, and European Society of Cardiology. (Full text: http://www.cardiosource.com/guidelines/guidelines/arrhythmias/va_scd.pdf ) Figure 6 presents a summary of major ICD trials as presented in the new guidelines. Details of MADIT II, SCD-HeFT, DINAMIT, and DEFINITE trials appear following the interview with George J. Klein, MD, FACC. Also, in 2005, the Centers for Medicare & Medicaid Services (CMS) expanded national coverage for implantable automatic defibrillators by including new indications. To read the new transmittal, click here. (Accessed October 16, 2006.)
(Enlarge Image)
Figure 6.
Major Implantable Cardioverter Defibrillator (ICD) Trials
Despite their efficacy, ICDs are not a universally used technology. In addition to obvious economic issues, other factors complicate the decision-making process. This discussion delves into the debate regarding the appropriate use of ICDs in various patient populations.
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