MedicalResearch.com Interview with:
Ben Cordon, PhD
NIHR Post-doctoral Academic Clinical Fellow
Specialist Registrar training in cardiology
James S. Ware, PhD, MRCP
Reader in Genomic Medicine
Group head within the Cardiovascular Genetics & Genomics Unit
Imperial College London
MedicalResearch.com: What is the background for this study?
Response: Non-ischaemic dilated cardiomyopathy is a common cause of heart failure and carries the risk of life-threatening ventricular arrhythmia. An implantable cardioverter defibrillator (ICD) can be life-saving in this condition. However, the decision to implant an ICD is not one that can be taken lightly – ICD insertion carries its own risks, such as infection or inappropriate shocks, and our ability to predict who will benefit from a device is currently far from perfect. Genetic sequencing is affordable and widely available and for DCM, like many diseases, it is hoped that genetic stratification may one day help deliver personalised management. In DCM, variants in the Lamin A/C gene for example are known to cause a phenotype with early and severe arrhythmias and, as a result, international guidelines advocate a lower threshold for ICD insertion in these patients. However, Lamin A/C is an infrequent cause of DCM. The commonest known genetic cause of DCM are protein-truncating variants in the gene encoding Titin (TTNtv), accounting for ~15% of DCM cases. We wanted to know if this group had a higher risk of arrhythmia than the general DCM population.
Earlier work from our group on this topic found that patients with TTNtv-associated DCM were more likely to have a clinical history of arrhythmia (composite of atrial and ventricular arrhythmia, including NSVT), at the time of their initial DCM diagnosis. But it was unclear if this was driven by ventricular arrhythmia, atrial arrhythmia, or both or if it would translate into a long-term risk of potentially dangerous ventricular arrhythmia of the sort for which an ICD can be life-saving. In another study we analysed a larger cohort of ambulant DCM patients but did not find an increased risk of ventricular arrhythmia – but this was a relatively low-risk group, with comparatively mild symptoms (NHYA I/II heart failure) and moderately impaired LV function. As a result, the overall arrhythmic event rate was low, meaning that the power to detect differences between the TTNtv and non-TTNtv groups was reduced.