Abstract
Purpose of ReviewNon-ischaemic dilated cardiomyopathy (DCM) occurs in 1 in 2500 individuals in the general population and is associated with considerable morbidity and mortality. Studies involving large numbers of unselected DCM patients have led to consensus guidelines recommending implantable cardioverter-defibrillator (ICD) implantation for protection against sudden cardiac death (SCD) in those with LVEF ≤35%. The purpose of this article is to review the literature for other potential markers including serological, electrocardiographic, echocardiographic, cardiac magnetic resonance, ambulatory ECG and genetic data, to highlight other potential markers that may optimise risk stratification for SCD in this cohort and thereby allow a more personalized approach to ICD-implantation.Recent FindingsRecent studies including the Danish study to assess the efficacy of ICDs in patients with non-ischemic systolic heart failure on mortality (DANISH) trial have questioned the benefits of ICD implantation in this group of patients with no changes in all-cause mortality. Recent pooled cohorts of patients with genetic DCM and in particular in those with Lamin A/C (LMNA) mutations have identified patients at increased risk of SCD and allowed the creation of algorithms to prognosticate SCD risk in mutation carriers. Furthermore, genetic testing has identified other DCM-causing genes including filamin C (FLNC) and RBM20 which may be associated with higher rates of ventricular arrhythmia.SummaryTo date, risk-stratification for SCD has been hampered by the utilisation of heterogenous subsets of idiopathic DCM patients and by use of static risk models where predictions are based on a single time point with a lack of consideration of disease progression. The current focus of personalised risk-stratification for SCD is shifting towards better characterisation of underlying DCM aetiology and the development of multi-parametric risk-stratification models that incorporate time-dependent disease characteristics and novel biomarkers.
Highlights
Non-ischaemic dilated cardiomyopathy (DCM) occurs in 1 in 2500 individuals in the general population [1] and predisposes to end-stage heart failure (ESHF) and malignant ventricular arrhythmia (VA)
This study demonstrated that Lamin A/C (LMNA) or desmosomal mutation-carriers were at greatest risk of VA regardless of left ventricular ejection fraction (LVEF) [63]
Whilst sudden cardiac death (SCD) can be prevented by implantation of primary prevention implantable cardioverter defibrillators (ICD), these devices come with their own risks
Summary
Non-ischaemic dilated cardiomyopathy (DCM) occurs in 1 in 2500 individuals in the general population [1] and predisposes to end-stage heart failure (ESHF) and malignant ventricular arrhythmia (VA). The annual incidence of sudden cardiac death (SCD) in DCM is 2-4% with sudden death accounting for up to half of all deaths [2, 3] This is reflected in registry data of survivors of an aborted cardiac arrest, where DCM is the underlying aetiology in 10-19% [4]. The resultant paradox is that many patients presenting with SCD have a LVEF that does not meet consensus criteria for primary prevention ICD implantation and often in those without preceding symptoms of heart failure [8]. A third of adverse events can occur late (>72 months) post symptom onset, despite optimal medical therapy (OMT) [9]. Given these limitations of LVEF as a solitary risk marker in DCM, alternative biochemical, clinical and imaging risk markers have been sought. Most studies are based on retrospective or observational registry data, but a number of potential candidates for risk predictors are emerging and discussed below
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