Infection in patients with subcutaneous implantable cardioverter-defibrillator: Results of the S-ICD Post Approval Study.

Journal: Heart Rhythm

Background: Early subcutaneous implantable cardioverter-defibrillator (S-ICD) studies included atypical cohorts of patients who were younger with fewer comorbidities. Recent S-ICD studies included patient populations with more comorbidities.

Objective: The goals of this study were to determine the incidence and predictors of S-ICD-related infection over a 3-year follow-up period and to use these results to develop an infection risk score.

Methods: The S-ICD Post Approval Study is a US prospective registry of 1637 patients. Baseline demographic characteristics and outcomes with 3-year postimplant follow-up were compared between patients with and without device-related infection. A risk score was derived from multivariable proportional hazards analysis of 22 variables.

Results: Infection was observed in 55 patients (3.3%), with 69% of infections occurring within 90 days and a vast majority (92.7%) within 1 year of implant. Late infections more likely involved device erosion; no infections occurred after year 2. The annualized mortality rate postinfection was 0.6%/y. No lead extraction complications or bacteremia related to device infection was observed. An infection risk score was created with diabetes, age, prior transvenous ICD implant, and ejection fraction as predictors. Patients with a risk score of ≥3 had an 8.8 hazard ratio (95% confidence interval 2.8-16.3) of infection compared with a 0 risk score.

Conclusions: Infection rates in the S-ICD Post Approval Study were similar to other S-ICD populations and not associated with systemic blood-borne infections. Late infection (>1 year) is uncommon and associated with system erosion. A high-risk infection cohort can be identified that may facilitate preventive measures. CLINCALTRIALS. NCT01736618.

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