Efficacy of Lipid Apheresis: Definitions and Influencing Factors

Abstract

The comparison of efficiency of currently available lipid apheresis systems has been hampered by different definitions of efficacy and poorly controlled apheresis conditions. This paper suggests definitions of efficacy and standardization of its determinants. The acute efficacy of risk factor reduction reflects the relative decrease of pathogen by a single treatment session compared to preapheresis levels. Standardization of treated plasma volume in relation to the patients plasma volume and correction of changes in plasma volume during the procedure are mandatory. Its determination is most useful in the technical evaluation of new systems. The long-term efficacy of risk factor reduction as compared to baseline is determined by mean interapheresis levels of e.g. LDL-C in the pseudo-steady-state after about 3 months of regular treatment. It is the major criterion for potential regression of coronary artery disease and absolute average plasma levels of 120 ≤ mg/dl LDL-C should be attained. It is influenced by the acute efficacy of the system, apheresis frequency and rebound kinetics. The clinical efficacy is defined by apheresis induced reduction of coronary morbidity and mortality. It is influenced by long-term risk factor reduction, the selectivity of the system as well as the control of non-lipid risk factors. Apheresis related effects on coronary artery disease comprise functional improvements of hemorheology and vasomotion as well as morphological benefits like regression of luminal narrowing and plaque stabilization. In conclusion, the acute efficacy of apheresis systems should be determined under strictly controlled conditions; however, as apheresis independent factors influence long-term efficacy and, even more so, clinical efficacy of the treatment, differences between the available systems are blurred so that factors like costs and ease of handling may eventually significantly influence the choice of procedure.