Biomedical Engineering Reference
In-Depth Information
deaths, cardiac causes accounted for 12 % and 26 %, respec-
tively. A subgroup analysis revealed that patients with an
LVEF < 26 % benefited most from ICD.
De fi brillators in Nonischemic Cardiomyopathy
Treatment Evaluation (DEFINITE)
The DEFINITE study was conducted from 1998 to 2002 and
included 458 patients with dilated nonischemic cardiomyo-
pathy. They were randomized into groups with pharmaco-
logical treatment with antiarrhythmic drugs or ICD
implantation. The results showed a significant reduction in
mortality in the ICD group and a significant reduction in the
incidence of sudden cardiac death [ 40, 43 ] .
Multicenter Unsustained Tachycardia Trial (MUSTT)
The MUSTT study was conducted from 1990 to 1998 and
included 704 patients with ischemic cardiomyopathy, an
LVEF < 40 %, and asymptomatic unsustained VT. A total of
351 patients underwent electrophysiologic testing and the
remaining 353 were only followed up. Patients with positive
electrophysiologic testing were randomized to receive either
no antiarrhythmic treatment or treatment with antiarrhythmic
drugs indicated by electrophysiologic testing. Patients in
whom antiarrhythmic drugs failed had an ICD implanted.
Patients were followed up for a period of 5 years. At 5 years,
all-cause mortality was 24 % in the ICD group, 55 % in the
group treated with antiarrhythmic drugs, and 48 % in patients
followed in the registry without treatment. A subgroup analy-
sis showed that only patients treated with ICD benefited from
electrophysiologic testing. Over a period of 5 years, 9 % of
ICD patients suffered cardiac arrest or arrhythmic death com-
pared with 37 % of patients treated with antiarrhythmic drugs
and 32 % of patients in the untreated group. The MUSTT
study supported the findings of the MADIT study.
Comparison of Medical Therapy, Pacing
and Defibrillation in Heart Failure (COMPANION)
The COMPANION study, conducted from 1997 to 2002,
included 1,520 patients with NYHA class III and IV heart fail-
ure symptoms and with an LVEF < 35 %, a QRS width > 120 ms,
and an LV end-diastolic dimension (LVEDD) > 60 mm,
regardless of the etiology of cardiac dysfunction. They were
randomized into groups treated with optimal pharmacological
therapy (n = 308), optimal pharmacological therapy plus car-
diac resynchronization therapy (CRT) with a pacemaker
(CRT-P) (n = 617), and optimal pharmacological therapy plus
CRT with a defibrillator (CRT-D) (n = 595). The study was
stopped early because of a reduction in mortality by more
than 20 % in the CRT-P arm in combination with the CRT-D
arm compared with the arm with pharmacological therapy
alone. A significant reduction in mortality in favor of CRT
was even more marked in the CRT-D group (43 %) [41].
MADIT II
The MADIT II was conducted from 1997 to 2001 and
assessed the use of ICD without prior electrophysiologic
testing in patients with an LVEF < 30 % and with an occur-
rence of fewer than ten ventricular ectopic beats or couplets
per hour during Holter monitoring. Patients with VT were
excluded. Patients were randomized into groups with phar-
macological treatment or ICD implantation. The study was
stopped prematurely. There was a 30 % reduction in mortal-
ity in the ICD group.
De fi brillator in Acute Myocardial Infarction Trial
(DINAMIT)
The DINAMIT was conducted from 1998 to 2002 and
included patients early after an acute coronary event, with an
LVEF
30 % evaluated 3 days or more after developing
myocardial infarction and a finding of reduced heart rate
variability evaluated by the standard deviation from an aver-
age length of cardiac cycles in sinus rhythm. This open, mul-
ticenter, randomized study included a total of 676 patients
who were randomized into groups with pharmacological
treatment with antiarrhythmic drugs or ICD implantation.
The conclusion drawn from the results of the DINAMIT was
that ICD implantation failed to have an impact on all-cause
mortality among the patients. Prophylactic ICD implantation
significantly reduced (by 58 %) the mortality from sudden
arrhythmic death; however, patients with ICDs had a
significantly higher (by 78 %) mortality rate from other than
arrhythmic causes during the follow-up period [ 42 ] .
£
Sudden Cardiac Death Heart Failure Trial (SCD-HeFT)
The SCD-HeFT, conducted from 1997 to 2003, included a
total of 2,521 patients who were randomized to receive pla-
cebo (n = 847), amiodarone (n = 845), or ICD implantation
(n = 829). All patients had chronic heart failure correspond-
ing to NYHA class II or III of ischemic or nonischemic etiol-
ogy and an LVEF < 35 %. This study revealed that, at 5 years
of follow-up, patients with an ICD showed an absolute reduc-
tion in mortality of 7.2 % compared with the control group of
patients. At 3 years of follow-up, all-cause mortality was
17.1 %, 24.0 %, and 22.3 % in the ICD group, the amio-
darone group, and the placebo group, respectively. At 3 years
of follow-up, all-cause mortality was 28.9 %, 34.1 %, and
35.8 % in the ICD group, the amiodarone group, and the pla-
cebo group, respectively. ICD implantation reduced all-cause
mortality by 23 % compared with placebo; the effect of ami-
odarone was not signi fi cant [ 42 ] .
Coronary Artery Bypass Graft Patch Trial (CABG-Patch)
The CABG-Patch was conducted from 1992 to 1998 and
assessed the effect of prophylactic ICD implantation in 900
patients with ischemic heart disease, LV dysfunction (with an
LVEF < 35 %), and a finding of ventricular late potentials.
Patients were randomized to receive either ICD or no treatment.
