Conclusion
It is clear that current methods for SCD risk stratification are inadequate, both in high-risk groups such as patients with reduced LVEF post AMI, patients with NIDCM and among the general public. Several novel risk-stratification techniques, including imaging, ECGbased methods and serum biomarkers, have shown considerable promise in refining SCD risk on top of conventional methods. However, such data has been derived from single-centre studies or studies involving a small number of centres, rather than large international randomised clinical trials. Hence, their clinical utility, effect on outcomes and cost-effectiveness require further evaluation and, consequently, these novel risk-stratification techniques have not yet been incorporated into current international guidelines on ICD therapy. Different approaches may be required for risk stratification of different populations. In high-risk groups, a combination of risk-stratification tests involving imaging and ECG-based techniques, in addition to conventional transthoracic echo to assess LVEF, is likely to be needed. Specific combinations may be required for patients with ischaemic and non-ischaemic cardiomyopathy, which will need to be validated prospectively. Repeat risk assessments may be appropriate in patients who are not deemed to be at high risk at baseline as the risk may change over time; hence, non-invasive tests may be more practical than invasive investigations such as EP testing. The approach to SCD risk stratification and reduction of risk in the general public will require a different angle because it is not possible or economically viable to perform sophisticated and expensive tests on a population level. The future in this area will probably lie in the use of improved clinical risk scores, possibly in combination with simple, inexpensive tests (ECGbased or serum biomarkers). These risk-stratification methods may be applied to certain subsets of the public who may be at increased risk, e.g. in males above the age of 40 and post-menopausal women, or those with other cardiovascular risk factors such as hypertension or diabetes. As it would not be practical to perform conventional randomised‚ controlled trials on a population level, validation of such an approach would require international epidemiological studies and good registry data.