Introduction: Appropriate Implantable Cardioverter Defibrillator (ICD) shocks may be caused by ventricular fibrillation (VF) or ventricular tachycardia (VT). Whether patients with ICD shocks due to VF should be treated differently from patients with VT is not clear. In addition, current guidelines do not distinguish between the two arrhythmias in ICD patients.
Aim of the study: was to evaluate the clinical characteristics, therapy, and prognosis of ICD patients with first VF shock compared with patients with first VT shock.
Methods: A total of 246 consecutive patients of a prospective single-centre ICD-registry who received a first appropriate ICD shock between 2012 and 6/2021 were analyzed. Patients with first ICD shock due to VF (n = 118) were compared with patients with first ICD shock due to VT (n = 128).
Results: Clinical characteristics of patients with first VF or VT shock were similar with respect to age, gender, ejection fraction, or underlying cardiac disease. Patients with first VT shock were more likely to receive new therapy for ventricular arrhythmias (48% versus 29%, p = 0.002) while rates of trigger optimization and heart failure optimization were similar in both groups (Table 1). Patients with a first VF shock had a better prognosis than patients with a first VT shock (p = 0.004, Figure 1). Conclusion: The clinical features of patients with first ICD shock due to VF or VT are similar. Patients with VT shock are more frequently treated with new antiarrhythmic drugs or ablation. Patients with a first VF shock have a better prognosis than patients with a first VT shock.

Table 1. Triggers and therapy after VT/VF shock

Figure 1