Complement activation in patients undergoing mechanical circulatory support

Contact of blood with artificial surfaces activates pro-inflammatory responses and the complement cascade. This may have broad implications on the post implantation fate of patients needing mechanical circulatory support. Therefore, we investigated the course and prognostic value of complement factors C3a and C5a in 66 patients supported with pulsatile ventricular assist devices. All patients were in severe cardiogenic shock, i.e., catecholamine dependent and in the intensive care unit, before implementation of mechanical circulatory support. Isolated left ventricular support (Novacor [Oakland, CA] or Thermo Cardiosystems, Inc. [TCI; Woburn, MA]) was used in 28 patients, and biventricular support (Berlin Heart [Mediport, Berlin, Germany]) in 38 patients. Before initiation of mechanical circulatory support, no statistically significant differences in C3a or C5a between surviving and nonsurviving patients with left ventricular assist devices (LVADs) were found. Patients with biventricular assist devices (BVADs) had significantly higher C3a (804 ± 364 ng/L) levels than patients with LVADs (536 ± 204 ng/L, p = 0.02) before mechanical circulatory support. Only C5a, only in the BVAD group, was able to predict patients' post implantation course before implantation of a ventricular assist device (p = 0.02). Three weeks after initiation of mechanical circulatory support, complement factors remained increased in all groups. There was no difference, however, in complement activation between patients with LVADs and those with BVADs. Patients not reaching transplantation had significantly higher C3a levels at this point than those successfully supported (p = 0.007). The degree of complement activation mainly depends on the severity of cardiogenic shock before initiation of mechanical circulatory support, and not on the device used. Patients with extremely high levels of complement activation before implantation of the device could be saved with BVAD rather than LVAD support. Patients who continued to have highly elevated complement levels 3 weeks after initiation of mechanical circulatory support bad unfavorable prognoses. Complement activation indicates the severity of cardiogenic shock before implementation of mechanical circulatory support and the degree of recovery from secondary organ dysfunction while on the device. It is fairly independent of the system used for mechanical circulatory support, and therefore can be applied to predict patients' post implantation course and outcome.