Indication to Cardioverter-defibrillator Therapy and Outcome in Real World Primary Prevention. Data from the IRIDE [Italian Registry of Prophylactic Implantation of Defibrillators] Study

Aims: Several trials demonstrated the life saving role of implantable cardioverter-defibrillators (ICD) in primary prevention of sudden cardiac death (SCD). The aim was to evaluate the clinical characteristics and 4-year outcome of consecutive patients treated in clinical practice by prophylactic ICD implantation on the basis of class I recommendations and up-to-date ICD programming.

Methods And Results: IRIDE multi-center, prospective and observational study enrolled 604 consecutive patients (mean age: 66 ± 10 years) treated by ICD between 01/01/2006 and 30/06/2010. Main characteristics were similarly distributed among the inclusion criteria of MADIT II (24%), SCD-HeFT (24%), COMPANION (26%) and MADIT-CRT (18%) trials, while a small number of patients met the MUSTT and MADIT (7%) inclusion criteria. Single-chamber ICDs were implanted in 168 (28%) patients, dual-chamber in 167 (28%) and biventricular in 269 (43%) patients. ATP programming was activated in 546 (90%) patients. Overall survival and rate of appropriate ICD intervention by ATP and/or shock at 12-24-36-48 months of follow-up were 94%, 89%, 80%, 75% and 16%, 28%, 37% and 50%, respectively. No difference in mortality rate between the groups who received or did not receive appropriate ICD interventions was demonstrated (p=ns).

Conclusions: The IRIDE study confirms the effectiveness in real world practice of ICD implantation in patients at risk of SCD. The life saving role of ICD therapy increases as the duration of follow-up is prolonged and the survival benefit is similar in patients who received or did not receive appropriate device treatment, thus suggesting a beneficial effect of up-to-date device programming.