ULTIMATEDCM Utilising Lifemap To Investigate Malignant Arrhythmia Therapeutic Efficacy in Dilated CardioMyopathy

Dilated cardiomyopathy (DCM) is a common yet challenging cardiac disease. Great strides have been made in improving DCM prognosis owing to heart failure, but sudden cardiac death (SCD) due to ventricular arrhythmias remains significant and challenging to predict. High-risk patients can be effectively managed with implantable cardioverter defibrillators (ICD) but because identification of what is high-risk is very limited; many experience the unnecessary adverse outcomes associated with an ICD implant, while others in the ‘low-risk’ experience avoidable sudden cardiac death. Risk stratification for sudden cardiac death has been long sought, and multiple methods have been developed to identify high risk patients. A common mechanism underlying ventricular arrhythmia has been shown to include cardiac restitution properties. Our research group has identified two novel restitution markers; regional repolarization instability index (R2i2) and peak electrical restitution slope (PERS) that has been shown to predict ventricular arrhythmia and sudden cardiac death. Nicolson et al., identified a cut-off for risk of VA or SCD in a group of patients with ischaemic cardiomyopathy; R2i2 > 1.03 and PERS > 1.21. Follow-up studies utilising the restitution markers in both ischaemic and non-ischaemic cardiomyopathy demonstrated positive results, however the ability to obtain these markers involved a degree of invasiveness.

The current method of obtaining R2i2 and PERS involve placement of a cardiac catheter or a pacing lead to stimulate the heart. An invasive method to risk stratify may not always be feasible to incorporate into routine clinical practice. Besides, it is essential to identify high risk patients prior to device implants as the aim is to help detect patients who will benefit from an ICD. Therefore, in this study we aimed to develop a non-invasive method of obtaining R2i2 and PERS. An exercise protocol was conducted along with a pacing stimulation test to assess if the markers were reproducible non-invasively. A digital surface ECG was recorded and analysed using a custom written software in MATLAB.