Page 710 - Cardiac Nursing

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686 PA R T I V / Pathophysiology and Management Disease
DISPLAY 28-4 2006 Indications for Implantable Cardioverter-Defibrillator Therapy—ACC/AHA/ESC
Practice Guidelines (continued)
Class I Class IIa Class IIb Class III
6. Patients with 6. Patients with arrhythmogenic 3. Incessant
catecholaminergic RV cardiomyopathy. VT/VF.
polymorphic VT with 7. Patients with Brugada
previous cardiac arrest. syndrome and documented
VT or Syncope—no prior
cardiac arrest.
8. Patients with
catecholaminergic
polymorphic VT
with syncope.
9. Patients with sustained
VT(stable) with normal
or near normal LV function
and no structural heart
disease.
has fewer shocks, which is important as ICD shocks are painful ICD. The study was actually stopped early on advice of the Data
and have been associated with significant anxiety, reduced QOL, and Safety Monitoring Board because the patients randomized
and depression. 66,67 If ATP should fail, subsequent therapies do to the ICD arm were found to have a 54% reduction in all-cause
include shocks. mortality compared with the patients receiving conventional
therapy. 69
Given the results of MADIT, Moss et al. reasoned that pa-
Syncope of Unknown Origin
Syncope in the setting of structural heart disease and inducible tients with previous history of MI and advanced LV dysfunc-
VT per electrophysiologic testing carries a high risk of SCD. tion had substrate for life-threatening cardiac arrhythmias and
Bass et al. 68 reported a sudden death rate of 48% at 3 years in would benefit from a prophylactic ICD without electrophysio-
patients with syncope of unknown origin and inducible sus- logical testing to confirm inducible VT. MADIT II, a random-
tained VT, compared with only 9% in patients with a negative ized, controlled, clinical trial was designed to evaluate the ben-
EP study. Syncope with induced VT/VF is considered a class I efit of the ICD in patients with a previous MI and an LV
indication for an ICD. Syncope in patients with structural ejection fraction of 30% or less. The study began in 1997 and
heart disease in which all invasive and noninvasive examina- was stopped in November of 2001. Analysis revealed a 31% re-
tions have failed to define a cause is likely to have an arrhyth- duction in the risk of all-cause mortality in heart attack sur-
50
mic event. These events include syncope of unexplained cause, vivors due to ICDs.
family history of sudden death, long QT interval and syncope The SCD-HeFT was a randomized control trial that enrolled
in association with Brugada syndrome (RBBB and ST segment patients with either ischemic or nonischemic cardiomyopathy
elevation). 56 with LVEF less than or equal to 35%. The patients were evenly
placed in three groups: conventional medial therapy plus placebo,
conventional medical therapy plus amiodarone, and conventional
High-Risk Patients medical therapy plus ICD. ICD therapy as compared with
placebo was associated with 23% reduction in the risk of all-cause
Prophylactic ICD implantation is now justified in patients who mortality. 51
are considered at high risk but have never had a spontaneous The Defibrillators in Nonischemic Cardiomyopathy Treat-
episode of sustained VT or VF. The goal is to prevent sudden ment Evaluation Trial (DEFINITE) enrolled patients with non-
death in the patient with LV ejection fraction of less than or ischemic dilated cardiomyopathy, EF 35%, with NYHA
equal to 30% and with history of MI (1 month after acute MI classes I and III HF. The patients were randomized to receive
and 3 months after coronary artery revascularization surgery). best medical therapy, with or without an ICD. The findings
The first randomized study to report primary prevention of showed a trend toward reduced mortality in the ICD group
SCD with direct comparison between the ICD and antiarrhyth- (Display 28-5). 70
mic drugs was the MADIT. MADIT was designed as a prophy- These studies have expanded ICD indications for the patient
lactic trial to determine if patients with coronary heart disease, with previous MI and advanced LV dysfunction, as well as those
LV dysfunction, and inducible VT, per electrophysiological test- patients with nonischemic cardiomyopathy who definitely bene-
ing, would have a better survival rate than those patients who fit from ICD therapy before sustaining a sudden cardiac arrest.
were treated with conventional medical therapy. MADIT estab- Other groups of patients may also benefit from prophylactic ICD
lished that the incidence of cardiac arrest and total mortality therapy. Those patients with idiopathic dilated cardiomyopathy,
were markedly reduced in the group of patients who received an hypertrophic cardiomyopathy, long QT syndrome, Brugada