December 28, 2016
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Subcutaneous ICD use linked to low in-hospital complication rates

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Early implementation of the subcutaneous implantable cardioverter defibrillator in the United States has been linked to low complication rates and increased rates of successful defibrillation threshold testing, despite being used frequently in patients with numerous comorbidities, according to new findings.

Daniel J. Friedman, MD, from division of cardiology, Duke University Hospital and Duke Clinical Research Institute, and colleagues conducted a retrospective analysis using the National Cardiovascular Data Registry ICD Registry, examining data on 393,734 ICD implants reported between Sept. 28, 2012 and March 31, 2015.

The researchers examined in-hospital outcomes, including death, complications, and defibrillation threshold (DFT) testing in patients that received subcutaneous ICDs. In a propensity-matched analysis of 5,760 individuals, patients receiving a subcutaneous ICD (S-ICD System, Boston Scientific) were compared with individuals who received conventional single-chamber and dual-chamber ICDs.

Among a total of 393,734 ICD implants (mean age, 67 years; 28% women), 0.9% (n = 3,717) were subcutaneous ICDs.

Adoption increasing

The rate of subcutaneous ICDs increased from 0.2% in fourth quarter of 2012 to 1.9% in the first quarter of 2015. Compared with those receiving conventional ICDs, those receiving subcutaneous ones were more likely to be younger, be female, be black, require dialysis and have a history of cardiac arrest, according to the researchers.

Among patients with subcutaneous ICDs who underwent DFT testing (n = 2,791), most were successfully defibrillated (92.7% 65 J; 94.2% 70 J; 94.4% 75 J; 99.7% 80 J).

Among those in the propensity analysis, the rate in-hospital complications associated with subcutaneous ICDs was 0.9%, comparable to 0.6% for those with single-chamber ICDs (P = .27) and 1.5% for those with dual-chamber ICDs (P = .11), Friedman and colleagues wrote.

Mean length of stay in those with subcutaneous ICDs was 1.1 days (standard deviation, 1.5), comparable to that of patients with single-chamber ICDs (1 day; standard deviation, 1.2; P = .77) and less than that of patients with dual-chamber ICDs (1.2 days; standard deviation, 1.5; P < .001), Friedman and colleagues wrote.

More study needed

“Although the favorable in-hospital outcomes suggest that wider adoption of the [subcutaneous ICD] may be warranted, additional studies with longitudinal follow-up are needed to better define the risk benefit and cost-effectiveness of this potentially disruptive technology relative to traditional transvenous ICDs,” the researchers wrote.

“The comparison between [subcutaneous] ICD implantation and single-chamber transvenous ICD implantation is highly relevant because it represents the usual clinical choice,” N. A. Mark Estes III, MD, of Tufts Medical Center, Tufts University School of Medicine, Boston, wrote in a related editorial. “If there is a clear indication for dual-chamber pacing, patients are most commonly not candidates for the [subcutaneous] ICD. Clinicians should remain mindful of this comparison between the [subcutaneous] ICD and the dual-chamber ICDs with transvenous leads in this analysis,” said. by Suzanne Reist

Disclosure: Friedman reports receiving educational grants from Boston Scientific and St. Jude Medical. Please see the full study for a list of the other researchers’ relevant financial disclosures. Estes reports consulting for Boston Scientific, Medtronic and St. Jude Medical.