For years now the implantable cardioverter-defibrillator (ICD) has served as a useful tool for treating patients suffering from ventricular fibrillation and tachycardia. Reports from nationwide data suggest however, that nearly forty percent of all ICD implantation are replacements of existing devices. With little known about the outcomes of these patients — with more than twenty percent of them having received shocks from their ICD prior to the replacement — the implications for long-term survival have raised concerns among the cardiology community.

Additional Resources New NCDR Report Sheds Light on CV Trends Quality Improvement for Institutions ICD Registry

In a study published in Heart Rhythm, Daniel Kramer, MD, Beth Israel Deaconess Medical Center, Boston, MA, and his team of researchers looked to identify clinical and procedural factors associated with death following ICD generator replacement and found that “non-cardiac comorbidities are associated with higher mortality following ICD replacement, which should be considered in the decision to undergo this procedure.”

After analyzing data from 111,826 patients (mean age 70.7, 75.5 percent male) from the NCDR's ICD Registry, the report found that atrial fibrillation, heart failure and left ventricular ejection fraction were independently associated with poorer survival. Additionally non-cardiac comorbidities including chronic lung disease, cerebrovascular disease, diabetes, and worsen renal function were also independently associated with worsened survival. Within five years more than forty percent of patients died (mortality at one, three, and five-year intervals were 9.8 percent, 27.0 percent, and 41.2 percent respectively), underlining the importance of evaluating patients' entire clinical history at the time of replacing an ICD generator.

Though the study's sample of patients was largely white and male, Kramer and his colleagues point out that the ICD Registry represents a nationwide sample of ICD recipients in the U.S. and thus reflects the current patterns of implantation. Kramer also emphasizes that while the data found can be used to support discussions with potential ICD recipients about their life expectancy and accumulated comorbidity, as well as help inform other prospective research on the matter, their findings alone should not be used to guide clinical decision-making for patients eligible for ICD replacement.

Keywords: Risk, Registries, Cardiology, Life Expectancy, Ventricular Fibrillation, Comorbidity, Stroke Volume, Defibrillators, Implantable, Diabetes Mellitus, Tachycardia, National Cardiovascular Data Registries, ICD Registry

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