Extracted from:
From Journal of Cardiovascular
Electrophysiology
Time-Dependence of Appropriate
Implantable Defibrillator Therapy in Patients with Ischemic Cardiomyopathy(J Cardiovasc
Electrophysiol. 2008;19(8):784-789)
Alawi A. Alsheikh-Ali, M.D.; Michael Homer, B.S.; Prasad V.
Maddukuri, M.D.; Benjamin Kalsmith, M.D.; N. A. Mark Estes Iii, M.D.; Mark S.
Link, M.D.
Abstract
Introduction: Little is known about
the risk of appropriate implantable cardioverter-defibrillator (ICD) therapy
outside the context of controlled clinical trials where routine practice
patients are followed for longer durations and questions of device replacement
frequently arise. We assessed the incidence and time-dependence of appropriate
ICD therapy in a routine clinical practice primary prevention population with
prior myocardial infarction (MI) and reduced left ventricular ejection fraction
(LVEF).
Methods
and Results: Patients with prior MI
and LVEF ≤35%, who received an ICD at our institution (1995-2005) for
primary prevention, were identified. Incidence and time-dependence of first
appropriate ICD therapy for ventricular arrhythmia (VA) and rapid VA (cycle
length ≤260 ms) were determined. Of 525 ICD recipients for primary
prevention, 115 (22%) had appropriate ICD therapy. Incidence of first
appropriate ICD therapy was highest in the first year postimplant (20%),
decreased to 12% in year 2, and remained at 6-11% yearly thereafter. A similar
trend was observed with rapid VA, a higher risk in the first year (6%), and a
lower but persistent risk thereafter (3.8% in year 7).
Conclusion: In
a routine clinical practice primary prevention population with prior MI and
LVEF ≤35%, the incidence of first ICD therapy for VA, including
potentially life-threatening VA, is highest in the first year postimplant, and
persists for up to seven years thereafter. Risk of first appropriate ICD
therapy persists over time, and thus replacement of ICDs appears to be indicated
for all patients.
Editor
Comments
Appropriate ICD
Therapy for Rapid VA - Potentially
life-threatening VA (cycle length ≤260 ms) that resulted in appropriate
ICD therapy – were observed in 33 patients
(6% over the mean follow-up of the study instead of 20% of appropriate standard
ICD Theraphy - for NOT Rapid VA).
Thereafter 6% is
an event rate that is similar to 2 year mean mortality rate of the
SCD-Heft population (EF<35%). 20% is an event rate that is more than 3 times
the 2 year mean mortality rate of SCD-Heft population.
Therefore only potentially life-threatening VA (cycle length ≤260
ms – 230 bpm) could be a surrogate of Sudden Death in this population as it was
found also for MADIT
II population sub-analysis. In the SCD-Heft TWA substudy and in the
MASTER study appropriate ICD theraphy was used and not life threatening VA that
resulted in appropriate ICD theraphy.