What are indications for implantable cardioverter-defibrillators (ICD) therapy in secondary prophylaxis?

Updated: Feb 13, 2017
  • Author: Daniel M Beyerbach, MD, PhD; Chief Editor: Jeffrey N Rottman, MD  more...
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Answer

Answer

An ICD is recommended as initial therapy in survivors of cardiac arrest due to VF or hemodynamically unstable VT. Published guidelines exclude cases in which there are “completely reversible causes.” [1]

The exclusion for completely reversible causes is somewhat controversial. As an example, an acute myocardial infarction (MI) predisposes to polymorphic VT, and the culprit lesion may be reversed with intracoronary stenting. However, we know that any patient who presents with an MI is at increased risk of recurrent MI, which may again precipitate an unstable ventricular arrhythmia. One school of thought suggests that such patients should undergo ICD implant, even though the cause of cardiac arrest is completely reversible, because the risk of recurrence is increased. However, current standard of care is that cardiac arrest during the initial hours of a define acute MI is not considered and indication for ICD implantation.

In another example, consider cardiac arrest secondary to transient prolongation of the QT interval, perhaps secondary to drug therapy. QT interval prolongation increases the risk of torsades de pointes, a potentially life-threatening arrhythmia. Withdrawal of the offending agent may normalize the QT interval, thereby reversing the cause of cardiac arrest. However, such a patient remains at risk of recurrent QT prolongation and subsequent cardiac arrest, perhaps from an electrolyte disturbance or as a result of ingestion of a different QT-prolonging agent.


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