Implantable cardioverter defibrillator therapies in left ventricular assist device patients

Background: The use of implantable cardioverter defibrillators (ICD) for primary prevention of sudden cardiac death is the standard of care in patients with advanced heart failure. For patients with end-stage heart failure, left ventricular assist devices (LVAD) are used as an additional therapy. However, evidence supporting the benefit of this combination remains limited. 

Methods: We screened all patients who underwent ICD follow-up in our heart center and also had an LVAD implanted for any ICD therapies. The follow-up period spanned from the time of LVAD implantation until heart transplantation, death, or the end of May 2024. ICD therapies were defined as either anti-tachycardia pacing (ATP) or shocks.

Results: A total of 47 patients had both an ICD and an LVAD implanted. Of these, 44 (93.6%) were male, with a mean age at LVAD implantation of 60.3 ± 9 years and the median INTERMACS score was 3 (range 1 to 5). Ischemic heart disease was present in 23 (49%) patients. At the time of LVAD implantation, 24 (51.6%) had a CRT-D, 13 (27.7%) a VVI-ICD, 9 (19.2%) a DR-ICD, and 1 (2.2%) an S-ICD implanted. The median follow-up duration was 48 months. During this period, 14 patients underwent heart transplantation, 1 had LVAD explantation due to infection and 9 patients died. At the end of the study, 24 patients still had an LVAD implanted. One patient dropped out of follow-up after 45 months because he moved away.

Throughout the follow-up, 27 patients (57%) received ICD therapies. Of these, 23 had only appropriate therapies, three (11.1%) experienced both appropriate and inappropriate therapies, and one (3.7%) received only an inappropriate ICD shock. All inappropriate therapies were due to atrial fibrillation with high ventricular rates.

Episodes of monomorphic ventricular tachycardia occurred in 14 patients (53.8%), ventricular fibrillation or polymorphic ventricular tachycardia in 7 (26.9%), and both types of episodes in 5 patients (19.2%). Among the 26 patients with appropriate therapies, 21 (80.8%) had multiple therapies, and 10 (38.4%) experienced an electrical storm, defined as three or more appropriate ICD therapies within 24 hours. Furthermore, 23 patients (88.5%) received at least one ICD shock, and 17 (65.4%) had multiple shocks.

Conclusion: ICD therapies are common in LVAD patients. Although inappropriate therapies occur, the majority are appropriate. However the survival benefit of ICDs in LVAD patients still remains unclear. Moreover, most patients tolerate ventricular arrhythmias quite well hemodynamically due to the LVAD and, therefore, experience ICD shocks while fully conscious. Until proven otherwise, the combination of LVAD and ICD remains the standard of care. Clinicians should aim for individualized programming of the ICD in these patients to avoid unnecessary ICD therapies.