P523Incidence of anti tachycardia therapies and mortality at one and two years in patients with and without persistent ICD indication at the time of generator replacement
Authors: Demarchi A , Cornara S , Pontillo L , Astuti M , Baldi E , Sanzo A , Savastano S , Vicentini A , Petracci B , Buia V , Frigerio L , Rordorf R 
Published: June 2020

BACKGROUND ICD implantation with or without resynchronization is an established therapy for the prevention of sudden cardiac death in patients with LV dysfunction. However, when elective replacement interval (ERI) approaches most patients undergo generator replacement (GR) even in the absence of persistent indication to ICD therapy- Moreover, at the time of GR patients are usually older and with more comorbidities as compared to the time of first implantation.

AIM The aim of our work was to evaluate the rate and predictors of mortality and to analyze.the incidence of appropriate ICD therapies after GR.

METHODS Our registry includes 323 patients with structural heart disease (SHD) implanted with ICD in primary prevention who underwent GR. Our population was stratified based on the presence or absence of persistent indication to ICD at the time of GR, which was defined as: LVEF ≤ 35% and/o history of appropriate ICD therapies during the first generator"s life. In each group the incidence of appropriate ICD therapies after GR, 1 and 2 years mortality after GR and multivariate predictors of 1 year mortality. Were analyzed. Comparisons between categorical variables were made using χ2 or Fisher Exact test when required and continuous variables were compared using Mann Whitney test.  Kaplan-Meier curves with Log Rank test were used to investigate 1 and 2 years mortality.

RESULTS In our population, 81% were male, 41% had ischemic heart disease, 60% had CRT-D. Median LVEF at the time of first implantation was 30%  (25-35), whereas at the time of GR was 35% (25-45); median age at GR was 64 (56-73) years. Notably 33.6% of our population no longer met ICD indication at the time of GR; this subgroup showed a significantly lower mortality at one and two years as compared to patients with persistent ICD indication: 1% vs 9% and 2.1% vs 13.5% respectively (figure 1 and 2). At multivariable analysis permanent AF (HR: 3.6; 95% CI 1.9-8.6) chronic renal disease (HR 4; 2.3-8.9), and persistent ICD indication  were independent predictors of 1-year mortality. When survival analysis was limited to patients implanted with single-chamber and dual-chamber devices only AF an renal insufficiency remained significantly predictors of mortality. Nevertheless, in this subgroup, the absence of persistent indication was associated with a significantly lower rate of appropriate ICD therapies after GR (0% vs 14.8%, p = 0.02). 

CONCLUSION The absence of persistent indication at the time of generator replacement was associated with a significantly better prognosis and a lower incidence of appropriate therapies after GR. Atrial fibrillation, renal insufficiency and persistent ICD indication significantly predicted 1 year mortality in our population. Our data suggest the importance of an arrhythmic vs. non-arrhythmic risk evaluation in the individual patient at the time of ICD generator replacement

Abstract Figure.