Biton Y, et al. – Researchers investigated the prognostic significance of implantable cardioverter-defibrillator (ICD) therapies, shock and anti-tachycardia pacing, delivered for different ventricular arrhythmia (VA) rates in this study involving 1,790 participants. According to the rate of treated VA only, patients were grouped as slow VA (< 200 beats per minute) and fast VA (≥ 200 beats per minute or ventricular fibrillation) for the first analysis. Researchers considered both the type of ICD therapy and VA rate for the secondary analysis. Patients who had no ICD therapy were considered a reference. Findings revealed an association of mortality with the rate of underlying VA rather than the type of therapy in patients with mild heart failure receiving ICD for primary prevention. Increased mortality was indicated by fast VA. No direct contribution of shock therapy to increased risk was found.