α2C-Adrenoceptor polymorphism is associated with improved event-free survival in patients with dilated cardiomyopathy

The sympathetic nervous system plays a central role in cardiac growth but its overstimulation is associated with increased mortality in patients with chronic heart failure. Pre-synaptic alpha2-adrenoceptors are essential feedback regulators to control the release of norepinephrine from sympathetic nerves. In this study we tested whether a deletion polymorphism in the human alpha2C-adrenoceptor gene (alpha2CDel322-325) affects progression of heart failure in patients with dilated cardiomyopathy (DCM).We genotyped and phenotyped 345 patients presenting with DCM in the heart transplant unit of the German Heart Institute, starting in 1994. Patients were treated according to guidelines (99% ACEI, 76% beta-blockers) and were followed until December 2002 or until a first event [death, heart transplantation, or implantation of a left ventricular assist device (LVAD) for a life-threatening condition] occurred. Mean follow-up time was 249 weeks (4.9 years) in event-free patients and 104 weeks (2 years) in patients with events. During follow-up, 51% of the patients exhibited an event: death (18%), implantation of LVAD as bridging for transplantation (7%), or heart transplantation (25%). By Kaplan-Meier analysis, DCM patients with the deletion variant Del322-325 in the alpha2C-adrenoceptor showed significantly decreased event rates (P=0.0043). Cox regression analysis revealed that the presence of the deletion was associated with reduced death rate (relative risk: 0.129, 95% CI: 0.18-0.9441, P=0.044) and event rates (relative risk: 0.167, 95% CI: 0.041-0.685, P=0.012).Alpha2C-adrenoceptor deletion may be a novel, strong, and independent predictor of reduced event rates in DCM patients treated according to guidelines.