Subcutaneous Implantable Cardioverter-Defibrillator Might Benefit Older Patients

"There are several unanswered questions that limit the generalizability of the S-ICD to more common ICD patients. One such question is the safety and efficacy of S-ICD implantation in older patients", wrote Dr Ahmadreza Karimianpour in an accompanying editorial. Also, there is still an age bias in enrollment, as recent prospective trials included patients with an average age of <65 years. To address the research gap, Dr Daniel J. Friedman and his team conducted a study to compare outcomes among older patients who received an S- or TV-ICD.

In this longitudinal retrospective outcomes study, the researchers included 16,063 patients with a median ejection fraction of 28.3 ± 8.9%. They used the "big data" by analyzing the National Cardiovascular Data Registry (NCDR) ICD registry to compare S-ICD (n = 991) and TV-ICD (n = 15,072) patients. Outcomes were ascertained from Medicare claims data. They used Cox regression or competing-risk models (with TV-ICD as reference) with overlap weights to compare death and nonfatal outcomes (device reoperation, device removal for infection, device reoperation without infection, and cardiovascular admission), respectively. They compared recurrent all-cause re-admissions using Anderson-Gill models.

Key findings of the study:

• The researchers noted that compared with TV-ICD patients, S-ICD patients were more often Black, younger, and dialysis-dependent and less likely to have a history of atrial fibrillation or flutter.
• Upon adjusted analyses, they found no differences between

♦ Device type and risk of all-cause mortality (HR: 1.020),

♦ Device reoperation (subdistribution [s] HR: 0.976),

♦ Device removal for infection (sHR: 0.614),

♦ Device reoperation without infection (sHR: 0.975),

♦ Cardiovascular readmission (sHR: 1.087), or

♦ Recurrent all-cause readmission (HR: 1.072).

The authors concluded, "In a large representative national cohort of older patients undergoing ICD implantation, risk of death, device reoperation, device removal for infection, device reoperation without infection, and cardiovascular and all-cause readmission were similar among S- and TV-ICD recipients."

Dr Ahmadreza Karimianpour and Dr Michael R. Gold wrote, "The authors should be commended for performing this large and carefully analyzed assessment of the NCDR database to compare the S-ICD and TV-ICD in older patients. These important results support and extend previous studies suggesting that the age bias in S-ICD use is not warranted with contemporary ICD devices and programming. So, hopefully, we can treat older patients with a new trick of avoiding TV leads while still protecting from SCD in the absence of pacing indications."

For further information:

DOI: https://www.jacc.org/doi/full/10.1016/j.jacc.2021.12.033

Keywords:

Subcutaneous implantable cardioverter-defibrillator, transvenous implantable cardioverter-defibrillator, S-ICD, TV-ICD, Sudden Cardiac Death, National Cardiovascular Data Registry, all-cause re-admissions, Device reoperation, Cardiovascular re-admission, Device removal for infection, JACC, Daniel J. Friedman.