The risk of ventricular arrhythmias in a Dutch CRT population: CRT-defibrillator versus CRT-pacemaker.

BACKGROUND: Patients eligible for cardiac resynchronisation therapy (CRT) have an indication for primary prophylactic implantable cardioverter defibrillator (ICD) therapy. However, response to CRT might influence processes involved in arrhythmogenesis and therefore change the necessity of ICD therapy in certain patients. METHOD: In 202 CRT-defibrillator patients, the association between baseline variables, 6-month echocardiographic outcome (volume response: left ventricular end-systolic volume decrease < ≥15 % and left ventricular ejection fraction (LVEF) ≤ >35 %) and the risk of first appropriate ICD therapy was analysed retrospectively. RESULTS: Fifty (25 %) patients received appropriate ICD therapy during a median follow-up of 37 (23-52) months. At baseline ischaemic cardiomyopathy (hazard ratio (HR) 2.0, p = 0.019) and a B-type natriuretic peptide level > 163 pmol/l (HR 3.8, p < 0.001) were significantly associated with the risk of appropriate ICD therapy. After 6 months, 105 (52 %) patients showed volume response and 51 (25 %) reached an LVEF > 35 %. Three (6 %) patients with an LVEF > 35 % received appropriate ICD therapy following echocardiography at ± 6 months compared with 43 patients (29 %) with an LVEF ≤ 35 % (p = 0.001). LVEF post-CRT was more strongly associated to the risk of ventricular arrhythmias than volume response (LVEF > 35 %, HR 0.23, p = 0.020). CONCLUSION: Assessing the necessity of an ICD in patients eligible for CRT remains a challenge. Six months post-CRT an LVEF > 35 % identified patients at low risk of ventricular arrhythmias. LVEF might be used at the time of generator replacement to identify patients suitable for downgrading to a CRT-pacemaker.

Measurements of electrical and mechanical dyssynchrony are both essential to improve prediction of CRT response.

INTRODUCTION: Predicting reverse remodeling after cardiac resynchronization therapy (CRT) remains challenging and different etiologies of heart failure might hamper identification of predictors. OBJECTIVE: Assess the incremental value of mechanical dyssynchrony besides electrical dyssynchrony for predicting CRT response. METHODS: 227 patients (51% ischemic) received CRT. Response was defined as ≥15% left ventricular end systolic volume decrease after six months. Prediction models were developed comprising clinical parameters and electrical dyssynchrony (Model A), subsequently complemented with mechanical dyssynchrony (Model B). Models were compared by area under the receiver-operating curve (AUC), net reclassification index (NRI) and integrated discrimination improvement (IDI) for the complete cohort, ischemic (ICM) and non-ischemic (NICM) subpopulations. RESULTS: Model B performed significantly better than Model A supported by AUC, NRI and IDI. Furthermore, model B significantly better predicted response for NICM than ICM. CONCLUSION: Electrical dyssynchrony and mechanical dyssynchrony are essential to predict CRT response. Nevertheless, response prediction for ICM remains challenging.

Implementation of guidelines for implantable cardioverter-defibrillator therapy in clinical practice: Which patients do benefit?

PURPOSE: Based on multiple large clinical trials conducted over the last decades guidelines for implantable cardioverter-defibrillator (ICD) implantations have been evolving. The increase in primary prophylactic ICD implantations challenges us to be critical towards the indications in certain patient populations. METHODS: We retrospectively collected patient characteristics and rates of appropriate and inappropriate ICD therapy, appropriate and inappropriate ICD shock and mortality of all patients who received an ICD in the University Medical Center Utrecht (UMCU) over the years 2006-2011. RESULTS: A total of 1075 patients were included in this analysis (74 % male, mean age 61 ± 13 years, left ventricular ejection fraction 30 ± 13 %); 61 % had a primary indication and 58 % had ischaemic heart disease. During a mean follow-up period of 31 ± 17 months, 227 of the patients (21 %) received appropriate ICD therapy (149 (14 %) patients received an appropriate ICD shock). Females, patients with a primary prophylactic indication and patients with non-ischaemic heart disease experienced significantly less ICD therapy. Only a few patients (54, 5 %) received inappropriate ICD therapy; 33 (3 %) patients received an inappropriate ICD shock. Fifty-five patients died within one year after ICD implantation and were therefore, in retrospect, not eligible for ICD implantation. CONCLUSION: Our study confirms the benefit of ICD implantation in clinical practice. Nevertheless, certain patients experience less benefit than others. A more patient-tailored risk stratification based on electrophysiological parameters would be lucrative to improve clinical benefit and cost-effectiveness.