The role of trigger factors in the occurrence of appropriate ICD shocks and their clinical and prognostic implications

Background: The role of triggers in the occurrence of appropriate implantable cardioverter-defibrillator (ICD) shocks due to ventricular tachyarrhythmias is not well known. The aim of the study was to assess the prevalence of trigger factors in appropriate ICD shocks and to analyze their prognostic impact on clinical outcome.

Methods: A total of 710 consecutive patients of a prospective single-center ICD-registry who received a first appropriate ICD shock between 2000 and 9/2021 were analyzed.

Results: In 35% of ICD patients with first ICD shock, at least one of the following triggers was found: Ischemia (22%), Compliance (9%), Decompensation (38%), Stress (12%), Technical (5%), Electrolyte/endocrinological disorder (22%) and Medication side effects (4%). The trigger factors can be summarized under the acronym ICD-STEMi. The prospective application of the ICD-STEMi scheme increased the rate of identified triggers from 32% to 56% (p < .001). Patients with triggered first ICD shock had an increased 5-year mortality rate (50% vs. 38%, p < .001). Patients with triggers did not show different mortality outcomes or recurrent ICD shocks whether they received arrhythmia therapy or not.

Conclusions: The evaluation of trigger factors after the occurrence of ICD shocks is mandatory and can be systematically evaluated using the acronym ICD-STEMi. Systematic evaluation of triggers using the ICD-STEMi scheme can identify triggers in about half of ICD patients with first appropriate ICD shock. Patients with triggered ICD shock have a 12% higher 5-year mortality rate.