Review Question - QID 106217

The single best indication for placement of an ICD in an adult is an ejection fraction less than 35%.

ICDs prevent sudden cardiac death from ventricular arrythmias. ICDs detect arrythmias and deliver a defibrillating shock to the heart to restore normal rhythm. ICDs are believed to be successful in terminating over 95% of ventricular arrythmias. Left ventricular systolic dysfunction, as indicated by an ejection fraction less than 35%, is currently the best indicator of benefit from ICD placement as primary prevention.

Turakhia reviews ICD placement. Patients with a history of myocardial infarction, coronary artery disease, cardiomyopathy, or heart failure, should have their ejection fraction evaluated. Other risk factors include nonsustained ventricular tachycardia, syncope, structural heart disease, and inherited heart failure or arrhythmia syndromes. Afflicted patients should discuss ICD placement with their cardiologist.

Ezekowitz et al. reviewed 12 randomized controlled trials with a total of 8,516 patients and concluded that ICDs reduced all-cause mortality for patients with left systolic dysfunction by 20%. The authors note that improved risk-stratification tools would be helpful in determining patients most likely to benefit from an ICD.

Illustration A shows a chest radiograph after placement of an ICD. The ICD generator lies in the upper left chest and the ICD lead in the right ventricle of the heart. Two opaque coils are present along the ICD lead.

Incorrect Answers:
Answer 1: Supraventricular tachycardia on EKG should be converted to sinus rhythm in the acute setting.
Answer 2: Atrial fibrillation indicates a need for anticoagulation therapy in patients with heart failure.
Answer 3: Aortic stenosis as a cause of heart failure is an indication for valve replacement.
Answer 5: Left ventricular hypertrophy is commonly seen in heart failure, but is not in itself an indication for ICD placement.