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Comparison of Subcutaneous and Transvenous ICD Therapy
Study Questions:
What are the long-term clinical outcomes of subcutaneous implantable cardioverter-defibrillators (S-ICDs) and transvenous ICDs (TV-ICDs)?
Methods:
The authors analyzed 1,160 patients who underwent S-ICD or TV-ICD implantation in two high-volume hospitals in The Netherlands. Propensity matching for 16 baseline characteristics, including diagnosis, yielded 140 matched pairs. Clinical outcomes were device-related complications requiring surgical intervention, as well as appropriate and inappropriate ICD therapy.
Results:
All 16 baseline characteristics were balanced in the matched cohort of 140 patients with S-ICDs and 140 patients with TV-ICDs (median age 41 years and 40% women). The complication rate was 14% in the S-ICD group versus 18% in the TV-ICD group (p = 0.8). The infection rate was 4.1% versus 3.6% in the TV-ICD groups (p = 0.4). Lead complications were lower in the S-ICD arm compared with the TV-ICD arm (0.8% vs. 11.5%, respectively; p = 0.03). S-ICD patients had more nonlead-related complications than TV-ICD patients (9.9% vs. 2.2%, respectively; p = 0.047). Appropriate ICD intervention occurred more often in the TV-ICD group (hazard ratio [HR], 2.42; p = 0.01). The incidence of appropriate (TV-ICD HR, 1.46; p = 0.36) and inappropriate shocks (TV-ICD HR, 0.85; p = 0.64) was similar.
Conclusions:
The complication rate in patients implanted with an S-ICD or TV-ICD was similar, but their nature differed. The S-ICD reduced lead-related complications significantly, at the cost of nonlead-related complications. Rates of appropriate and inappropriate shocks were similar between the two groups.
Perspective:
A randomized trial comparing outcomes of patients with S-ICD and TV-ICD has not been published. The present study employs a propensity-matched cohort in an attempt to provide insight on how outcomes may vary between S-ICD and TV-ICD patients. In the study, the complication rates were similar, albeit they differed. As expected, there were fewer lead complications in the S-ICD, but S-ICD patients had more pocket erosions, defibrillation threshold testing failures, and device failures than TV-ICD patients. A major limitation of S-ICD is lack of capacity to pace terminate ventricular tachycardia. However, this study showed that appropriate and inappropriate shocks were delivered at equal rates in both groups. This may be related to extended detection time in S-ICDs.
Keywords: Arrhythmias, Cardiac, Defibrillators, Implantable, Equipment Failure, Heart Failure, Hospitals, High-Volume, Secondary Prevention, Tachycardia, Ventricular, Treatment Outcome
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