Shocks and increased mortality in implantable cardioverter-defibrillator patient: impact of shock burden

ICD shocks have been linked to higher mortality, but whether they directly contribute to risk is unclear. We evaluated the association between ICD shocks and survival after adjusting for baseline mortality using the Seattle Heart Failure Model. Among 425 patients followed for a median of 41 months, 59% experienced ≥1 shock and 40% died. Any shock was associated with increased mortality (HR 1.55; 95% CI 1.07–2.23). Mortality rose with greater shock burden, while antitachycardia pacing alone did not increase risk. These findings suggest ICD shocks themselves may contribute to higher mortality.