Implantable cardioverter-defibrillator therapy to reduce sudden cardiac death in adults with congenital heart disease: A registry study

Implantable cardioverter-defibrillator therapy to reduce sudden cardiac death in adults with congenital heart disease: A registry study

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Slater TA, Cupido B, Parry H, Drozd M, Blackburn ME, Hares D, Pepper CB, Birkitt L, Cullington D, Witte KK, Oliver J, English KM, Sengupta A.J Cardiovasc Electrophysiol. 2020 Jun 24. doi: 10.1111/jce.14633. Online ahead of perindopril: 32583559

Take Home Points:

  • The decision to implant a cardioverter defibrillator (ICD) is challenging and current guidance on the subject relies heavily on registry data and consensus.
  • The largest studies have focused specifically on tetralogy of Fallot and transposition of the great arteries, though a large metanalysis included rarer conditions.
  • Similar proportions received appropriate defibrillation in the primary and secondary prevention groups.
  • Patients with advisory leads accounted for 38% of all complications in the primary prevention cohort and 33% in the secondary prevention cohort raising the possibility that future cohorts, with more reliable ICD hardware, may be exposed to lesser risk from inappropriate therapies and device revisions.

Dr Khyati Pandya

Commentary from Dr. Khyati Pandya (Augusta, GA), section editor of Congenital Electrophysiology Journal Watch:  The authors describe their experience with follow-up of patients with adult congenital heart disease at risk for sudden cardiac death from a large quaternary center in the UK, who underwent implantation of an ICD. The most up to date European guidelines are not dedicated to the ACHD population and a recent study implied that these, and the US guidelines, have limited ability to predict sudden death.

The objective of the current study was to gather data on the consequences of ICD implantation, including appropriate and inappropriate therapy, as well as the rate of complications over a long duration of follow up.

All ACHD patients with an ICD implanted between March 2002 and March 2020 were included.

Standard secondary prevention indications for ICD implantation comprised: cardiac arrest due to ventricular arrhythmia or sustained ventricular tachycardia (VT) with symptoms or other evidence of hemodynamic compromise, in line with established guidelines. The remaining patients were classified as requiring an ICD for primary prevention. Thus the subset of patients qualifying as candidates for primary prevention of sudden cardiac death were not well defined.

Baseline Characteristics

primary prevention

table 2 outcomes

figure 2 a

This observational study comprised of a cohort of 136 individuals with ACHD: 79 with primary prevention device indications and 57 with secondary prevention ICDs. It incorporates a longer average follow up period than previous similar studies: 8.3 and 9.6 years in the respective primary and secondary cohorts compared with a maximum of 4.6 years in the existing literature.

An appropriate therapy rate of 38% of the full cohort, equally balanced in each group, balanced against a rate of inappropriate therapy of 26% (30% for primary prevention and 19% for secondary prevention) are comparable to those in previous studies, as noted by the authors.

Risks and benefits of ICD insertion are carefully balanced, particularly in the relatively young group of patients with ACHD. Both inappropriate and appropriate shock therapies have been associated with increased rates of anxiety, depression and reduced social function. An inappropriate rate of shock in 16% of patients compares well with the overall proportion of 25.2% of patients receiving inappropriate cardioversion/defibrillation in the – by Vehmeijer et al. ((Anatol J Cardiol 2018; 19: 401-3) )

Sudden cardiac death (SCD) is a major cause of mortality, accounting for roughly 19%– 26% of all deaths in ACHD patients, often occurring before the age of 40 years. As SCD in ACHD patients is often due to ventricular arrhythmias, implantable cardioverter defibrillator (ICD) may seem an ideal option to prevent SCD in these patients. However, ACHD patients are also at an increased risk of complications due to ICD implantation and inappropriate ICD shocks. In addition, the financial aspect of ICD implantation is also of importance. Both – underimplantation of ICDs, causing mortality in ACHD patients because of a preventable cause of death, as well as over-implantation, are important issues. The ICD recommendations in the current guidelines on the primary prevention of SCD in ACHD patients currently only recognize 35%-41% of SCD cases and have a poor discriminative ability. It is therefore highly important to focus future research on ICD recommendations specific for ACHD patients. This will require international multicenter cooperation, funding, and great effort from physicians and researchers as the population of ACHD patients continues to increase and grow older. Achievement of these goals in the COVID era, as well as the resource depleted post COVID era is likely to pose significant challenges.