ICD in post myocardial infarction LV dysfunction

ICD in post myocardial infarction LV dysfunction

ICD in post myocardial infarction LV dysfunction: Previous myocardial infarction (MI) has been documented in as many as 75% of cases of sudden cardiac arrest (SCA). Sudden cardiac death (SCD) rates in those with previous MI is 4-6 times that in general population. High risk indicators are late ventricular tachycardia (VT) / ventricular fibrillation (VF), left ventricular (LV) dysfunction, frequent premature complexes (VPC), non sustained ventricular tachycardia (NSVT) and inducible ventricular tachycardia at electrophysiology study (EPS). Implantable cardioverter defibrillator (ICD) is recommended in VT/VF survivors with no reversible etiology (secondary prevention). If there is inducible VT/VF, those with left ventricular ejection fraction (LVEF) less than or equal to 40% need an ICD. The cut off left ventricular ejection fraction is less than or equal to 35% in symptomatic patients. The cut off is lower at LVEF of 30% or less regardless of any arrhythmic events or symptoms [1]. ICD does reduce mortality significantly in those with post myocardial infarction left ventricular dysfunction.

Early ICD implantation was not shown to reduce mortality in previous studies, though recent studies, especially with risk stratification have shown some promise. The earlier negative trial was DINAMIT [2].

Reference

  1. Arthur J Moss, Wojciech Zareba, W Jackson Hall, Helmut Klein, David J Wilber, David S Cannom, James P Daubert, Steven L Higgins, Mary W Brown, Mark L Andrews, Multicenter Automatic Defibrillator Implantation Trial II Investigators. Prophylactic implantation of a defibrillator in patients with myocardial infarction and reduced ejection fraction. N Engl J Med. 2002 Mar 21;346(12):877-83.
  2. Stefan H Hohnloser, Karl Heinz Kuck, Paul Dorian, Robin S Roberts, John R Hampton, Robert Hatala, Eric Fain, Michael Gent, Stuart J Connolly, DINAMIT Investigators. Prophylactic use of an implantable cardioverter-defibrillator after acute myocardial infarction. N Engl J Med. 2004 Dec 9;351(24):2481-8.