77 * The incidence of appropriate ICD therapy in heart failure patients

Abstract

Introduction: A major concern for patients receiving an implantable cardioverter defibrillator (ICD) is the rate of ICD shocks. This is an important consideration when counselling a patient prior to implantation but it is challenging to provide an accurate estimate due to the reported heterogeneity of this outcome in clinical trials and the common disjoint between clinical trials and real-world experience. An additional concern for physicians since the publication of MADIT-RIT is the rate of ATP therapy. Contemporary, real-world UK data in heart failure patients is lacking. Aim: We sought to determine the incidence of appropriate ICD therapy in our real world cohort of heart failure patients. Methods: Patients under active ICD follow-up in 2011 and 2012 were identified at two UK tertiary cardiology centres. Patients who had heart failure with an ejection fraction (EF) ≤35% (or severely impaired) were included. Each patient had at least 12 months follow-up data. Results: Data were analysed for 479 patients in 2011 and 537 patients in 2012: median age at implant 67years (IQR 58-73), median EF 25% (IQR 20-30). Underlying aetiologies were ischaemic (74%), DCM (15%) and unknown(11%). Indications were primary prevention (55%), secondary prevention (43%) or not documented (2%). Results are summarised in the table. Conclusions: There was no significant difference in the rates of ICD therapy (shock or ATP) between those patients with a primary or secondary prevention indication. On average the annual rate of appropriate shocks for primary and secondary prevention were 7.7% and 11.5% respectively. Contemporary data detailing rates of appropriate therapy in secondary prevention patients is particularly lacking and our data shows rate of appropriate shocks in the secondary prevention group was much lower than the some older trials (45% in the first year of the AVID trial). This highlights the importance of establishing contemporary event rates in order to best inform patients. Our data would suggest that the rate of ATP in our primary prevention cohort is comparable to that seen in the conventional arm of MADIT-RIT. As such it will be of interest to repeat this data collection now that more conservative programming has been implemented. | | Primary Prevention | Secondary Prevention | Fishers exact test (P=) | | ---------------------- | ------------------ | -------------------- | ----------------------- | | Appropriate shock 2011 | 8.2% | 14.1% | 0.052 | | Appropriate ATP 2011 | 14.3% | 15.7% | 0.743 | | Appropriate shock 2012 | 7.1% | 8.9% | 0.413 | | Appropriate ATP 2012 | 12% | 14.4% | 0.415 | Table showing the proportion of patients receiving ICD therapy annually in 2011/12 categorised by indication for ICD implantation.