All concepts, explanations, trials, and studies have been
re-written in plain English and may contain errors. I am
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ICDs-Risk_of_CHF_from MADIT-2_study

June 12, 2006 - In patients with both an ICD and ischemic
cardiomyopathy, the first proper zap greatly increases the
risk of a heart failure episode. Strangely, an unneeded or
"inappropriate" shock does not affect this risk level at all.
	Researchers studed the MADIT-2 trial, which
was done in 2002. It included 1232 heart attack patients
with EF less than 30%. Patients got single-chamber or dual-
chamber ICDs; or just took standard meds. The trial was
about 20 months long and 24 patients dropped out.
	Single-chamber ICDs (402 patients) started
their pacing action when heart rate went below about 50
beats per minute. Dual-chamber ICDs (313 patients) started
pacing at about 60 beats per minute. Researchers say 92%
of single-chamber patients had very little or no pacing
during the trial. Right-side pacing was happening over 50%
of the time in about 66% of dual-chamber patients.
	Both kinds of ICD raised heart failure risk after
the first "appropriate" shock but not after an "inappropriate"
shock. This suggests it is not the ICD "zap" itself that raises
HF risk.
	More single-chamber device patients (22%) and
dual-chamber patients (25%) had a HF hospitalization than
meds-only patients (17%). HF risk was less in device
patients taking a beta-blocker.
	Okay, so what does this mean? Well, you 
could say that a life-saving ICD shock sort of turns
sudden death risk into heart failure risk. So ICD patients
should get more aggressive meds therapy and make
more aggressive life style changes to lower their risk of
HF should their ICDs save them from sudden death.

Source:   Circulation. 2006 Jun 20;113(24):2810-7. Epub 2006
               Jun 12.
Title:      Causes and consequences of heart failure after
              prophylactic implantation of a defibrillator in the
              Multicenter Automatic Defibrillator Implantation
              Trial II.
Authors: Goldenberg I, Moss AJ, Hall WJ, et al.