Evaluating real-world mortality risk after defibrillator implantation

Protection against the increased risk of sudden cardiac death (SCD) due to ventricular arrhythmias is offered by the implantation of cardiac defibrillators. A life-expectancy of less than one year is usually a contraindication to the implantation of these devices. We evaluated the outcomes of all those who received defibrillator implantation for any clinical indication at our centre in the same year that early (<12 months) death notifications occurred. This is a single-centre retrospective study on the outcomes of all patients who had a transvenous defibrillator implant in 2015. All transvenous defibrillator devices implanted for both primary and secondary prevention of SCD were included. Patient demographic data and device data were studied. Data from 235 patients were analysed. In a follow-up period of 66.2 ± 3.8 months, 77 (32.8%) of the study cohort died; 20 (8.5%) of these patients died less than 12 months post-implant. None of the deaths were directly arrhythmia related. Factors that were significant in predicting mortality included age and ejection fraction <35% (p<0.01). From a preprocedure biomarker perspective, an increased red cell distribution width (RDW) was strongly associated with early mortality risk on univariate and multi-variate analysis (p<0.001). Receiver operator characteristics (ROC) curve analysis found that the optimal cut-off for RDW was 14.75% (area under curve 0.75; sensitivity 0.69; specificity 0.77; p<0.001). In conclusion, there are limitations in fully assessing patient prognosis despite current guidance. Universal clinical frailty scores that incorporate biomarkers may be helpful in enhancing this pre-assessment process to improve the evaluation of the risk of early non-arrhythmic-related death for implantable cardioverter defibrillator candidates.