Serum complement activation in congestive heart failure

Background Although activation of the complement system in myocardial infar ction and cardiopulmonary bypass has been shown to contribute to myocardial injury, its role in congestive heart failure (CHF) is unknown. The purpose of this study was to determine the presence of terminal complement activat ion and its relation to clinical outcomes in patients with CHF. Methods we measured serum levels of the terminal complement complex C5b-9 i n 36 patients with symptomatic heart failure and left ventricular ejection fraction <40%. We compared the serum C5b-9 levels of these patients with CH F with a group of 12 age-matched control patients. Combined clinical outcom es (death, urgent heart transplantation, or hospitalization with worsening heart failure) at 6 months were determined. Results The serum C5b-9 [median (25th to 75th percentiles)] levels in 36 pa tients with CHF [101.5 ng/mL (40 to 164)] were significantly (P = .003) hig her than in the 12 control patients [36.5 ng/ml (22 to 50)]. Significantly more of the patients with CHF with the highest levels of C5b-9 (highest 50t h percentile) had New York Heart Association class IV symptoms (67% vs 33%; P = .04) and adverse clinical outcomes by 6 months (56% vs 17%; P = .02) c ompared with the patients with CHF with lower levels (lowest 50th percentil e). Conclusions We have described a significant elevation in circulating C5b-9, the terminal complement complex, in patients with symptomatic heart failur e and have observed on association between high levels of C5b-9 and near-te rm adverse events.