NEW INSIGHTS INTO IDENTIFICATION OF PATIENTS AT RISK FOR SUDDEN CARDIAC DEATH
Michael E. Cain, M.D., University at Buffalo, Buffalo, NY, USA
The annual incidence of sudden death (SCD) in the United States is between 184,000 and 462,000, with estimates that 50% to 70% of deaths are due to VT or VF. Availability of therapies that have been shown to reduce SCD in various at-risk groups, including beta-blockers, ACE- inhibitors, statins, aldosterone blockers, and the ICD, underscore the need to accurately identify patients who will develop VT/VF within some specified time period, and exclude those who will not experience SCD. Multiple tests have been evaluated, but currently no optimal strategy for risk stratification exists. The most widely used strategy is based on ejection fraction and falls short of the optimal goal. Current approaches dichotomize patients into low- and high-risk groups. Risk, however, is a continuum; and many risk functions are likely dynamic. Moreover, the majority of episodes of SCD occur in patients with low to intermediate risk factors. The risk stratification field requires further development. New short-term strategies focus on using current tests in combination to better define individual patients identified to be at high risk based on one test result who will not benefit from ICD therapy.
Longer-term strategies must focus on:
1) do current risk stratification methods optimally detect VT/VF vulnerability;
2) has the substrate for VT/VF changed;
3) when and how often risk should be assessed; and
4) the role of genetic testing.
Answers will re-focus the field on who is at risk and who will benefit from therapy, rather than who does not require ICD implantation.