Risk Stratification in Post-MI Patients Based on Left Ventricular Ejection Fraction and Heart-Rate Turbulence

Objectives: Development of risk stratification criteria for
predicting mortality in post-infarction patients taking into
account LVEF and heart-rate turbulence (HRT). Methods: Based on
previous results the two parameters LVEF (continuously) and
turbulence slope (TS) as an indicator of the HRT were combined for
risk stratification. The method has been applied within two
independent data sets (the MPIP-trial and the EMIAT-study).
Results: The criteria were defined in order to match the outcome of
applying LVEF ( 30 % in sensitivity. In the MPIP trial the optimal
criteria selected are TS normal and LVEF ( 21 % or TS abnormal and
LVEF ( 40 %. Within the placebo group of the EMIAT-study the
corresponding criteria are: TS normal and LVEF ( 23 % or TS
abnormal and LVEF ( 40 %. Combining both studies the following
criteria could be obtained: TS normal and LVEF ( 20 % or TS
abnormal and LVEF ( 40 %. In the MPIP study 83 out of the 581
patients (= 14.3 %) are fulfilling these criteria. Within this
group 30 patients have died during the follow-up. In the
EMIAT-trial 218 out of the 591 patients (= 37.9 %) are classified
as high risk patients with 53 deaths. Combining both studies the
high risk group contains 301 patients with 83 deaths (ppv = 27.7
%). Using the MADIT-criterion as classification rule (LVEF ( 30 %)
a sample of 375 patients with 85 deaths (ppv = 24 %) can be
selected. Conclusions: The stratification rule based on LVEF and TS
is able to select high risk patients suitable for implanting an
ICD. The rule performs better than the classical one with LVEF
alone. The high risk group applying the new criteria is smaller
with about the same number of deaths and therefor with a higher
positive predictive value. The classification criteria have been
validated within a bootstrap study with 100 replications. In all
samples the rule based on TS and LVEF (= NEW) was superior to LVEV
alone, the high risk group has been smaller (( s: 301 ( 14.5 (NEW)
vs. 375 ( 14.5 (LVEF)) and the positive predictive value was larger
(( s: 27.2 ( 2.6 % (NEW) vs. 23.3 ( 2.2 % (LVEF)). The new criteria
are less expensive due to a reduced number of high risk patients
selected.