OBJECTIVES: In Italy, information about clinical outcomes and economic implications of the treatment with implantable cardioverter defibrillator (ICD) are lacking. We evaluated time trend in ICD therapy from 2000 to 2008 in Lombardy, an Italian region with universal health care coverage for more than 9 million people. Subsequently, we analysed survival and direct costs following a first implant. METHODS: We extracted data from DENALI, a data warehouse that organizes health care administrative data concerning subjects covered by Lombardy Health System(HS). We estimated annual rates of first implant and of replacement from 2000 to 2008. We computed the substitution rate using the real person-time at risk, assessed on subjects with ICD. The cohort of patients who underwent a first ICD implantation between 2005 and 2007 was followed from discharge to December 31, 2008 in order to evaluate mean annual total healthcare cost per-capita and mortality. RESULTS: The annual rate of first ICD implant (per million-persons) increased, from 55 in 2000 to 236 by 2008. The use of ICD in Lombardy was approximately 2 times higher than in Europe and 3-4 times lower than in US. The replacement rate was around 10 (per hundred implant-year) with a peak in 2005. The hospitalization for a first ICD implant cost €23,814 (CI95%, 23,676-23,960) on average. During follow-up, 15.4% of patients died and the HS bore a mean annual cost of €4,354 (CI95% 4,226-4,485) per-capita: 17% due to drugs, 12% to outpatient visits and 71% to hospitalizations. Younger patients reported lower costs in drug treatments and outpatient visits and a higher expenditure for hospitalizations. CONCLUSIONS: ICD use is growing and it’s important to assess the efficacy and the burden of this therapy, given the economic implications and differences in use among countries. Healthcare administrative databases are a useful tool, as they provide information about large unselected populations.