What are the indications for implantable cardioverter-defibrillator (ICD) therapy?

Updated: Oct 11, 2019
  • Author: Daniel M Beyerbach, MD, PhD; Chief Editor: Jeffrey N Rottman, MD  more...
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Indications for implantable cardioverter-defibrillator (ICD) implant can be divided into two broad categories: secondary prophylaxis against sudden cardiac death and primary prophylaxis. Multiple studies have shown the ICD to be superior to antiarrhythmic drug therapy in patients with a history of life-threatening ventricular tachycardia (VT) and ventricular fibrillation (VF). Therefore, the indications for secondary prophylaxis are well supported by clinical evidence gained from randomized clinical trials. [1] Currently, however, indications for primary prophylaxis account for most of ICD implants, even though the evidence for such implants is often less well established. Measurable quantitative benefit is smaller in the primary prophylaxis population than in the secondary prophylaxis population.

Wilcox et al investigated the clinical effectiveness of cardiac resynchronization (CRT) and ICD therapy as a function of sex from data in 8936 outpatients with heart failure and reduced ejection fraction (≤35%) and found a substantially reduced 24-month mortality in eligible men and women with heart failure and reduced ejection fraction. [34]  The data was obtained from the Registry to Improve the Use of Evidence-Based Heart Failure Therapies in the Outpatient Setting (IMPROVE HF) for vital status (alive/dead) at 24 months. The clinical benefit associated with ICD/CRT-D therapy was similar in both sexes. [34]

Using data from the Get With The Guidelines-Heart Failure Registry and the National Cardiovascular Data Registry's ICD Registry, Pokorney et al compared the relationship of primary prevention ICDs with mortality in 852 Medicare, racial/ethnic minority patients (nonwhite race or Hispanic ethnicity) and 2070 white non-Hispanic patients. [35] Minority ICD patients had a lower adjusted 3-year mortality rate (44.9%) than their non-ICD counterparts (54.3%). Similarly, white non-Hispanic ICD patients had a lower adjusted 3-year mortality rate (47.8%) than their non-ICD counterparts (57.3%). The investigators found no significant interaction between race/ethnicity and lower mortality risk with ICD; they indicated that these results support the use of a similar approach in selecting ICD patients, irrespective of race or ethnicity. [35]

Investigators have looked at ongoing indications for ICD therapy at the time of elective device replacement. In one prospective cohort study, 21% of patients received appropriate ICD therapy within 3 years following device replacement, even if they had never received appropriate therapy from their originally implanted device. For patients who had received appropriate therapy from their first device, 48% received appropriate therapy over the same 3-year period. [36]

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