·
The MADIT II study was stopped early due to 30 percent mortality
reduction in heart attack survivors with implantable defibrillators. The study
was designed to determine whether implantable defibrillators improve survival
when compared to drug therapy alone in heart attack survivors with moderate
impairment <30% of the left ventricle.
Electrophysiology studies were not included in this study.
·
This study will probably increase the pool of candidates indicated for
ICD therapy from its current level of 300,000 by two fold to 600,000 based on
MADIT II indications. They expect MADIT
II will allow cardiologists to send their patients with an EF <30%, directly
to ICD therapy, bypassing the EP for proof of VT.
·
There are currently 61,000(current NASPE figures) ICDs implant annually
in USA. Based on an average price of
$22,000 per device, payers spent $1.3 billion for ICDs. It is not likely that payers will be willing
to spend $6.6 billions more for MADIT II patients without risk stratifying
those patients in some way.
·
MicroVolt T Wave Alternans test can non-invasively risk stratify
patients at elevated risk of SCD including those with CHF, <40% EF, post MI,
and syncope. There are over 10 million
patients at elevated risk of SCD.
According to the AHA, these, these patients
constitute 4.7 million for CHF,; 7.3 million for post MI, and 600K for
syncope. This indicates a very large
“at risk” population that far exceeds those indicated based on MADIT II
results.
·
Two studies suggest MTWA may be effective in risk stratifying the MADIT
II population.
·
The Klingenheben CHF study ( The Lancet August 2000 ) demonstrated that
patients with CHF (mean EF of 28%).that tested he negative for MTWA had NO events in
the 24 month follow up – 100% sensitivity.
·
The combined Gold multi-center ( JACC 2000;36:2247-53) and Klingenheben
CHF studies (more than 400 patients) demonstrated that NO patients with
negative MTWA that met MADIT II criteria with an EF < 30% had an event in
the 14 month follow up.