Changes in myocardial vasoreactivity after drastic reduction of plasma fibrinogen and cholesterol: A clinical study in long-term heart transplant survivors using positron emission tomography

Background: Given the central importance of the microvasculature in heart transplant recipients, we investigated the possibility of increasing cardiac perfusion after reduction of low-density lipoprotein (LDL)-cholesterol, lipoprotein (a), C-reactive protein (CRP) and fibrinogen plasma levels after apheresis treatment in transplanted patients. Methods: Ten long-term heart transplant recipients were examined with positron emission tomography (PET) to measure myocardial perfusion before and after a single heparin-mediated extracorporeal LDL/fibrinogen precipitation (HELP)-apheresis treatment. PET studies were performed the mornings before and after the apheresis treatment. Myocardial blood flow at rest and during adenosine-induced hyperemia was measured using ¹³N-ammonia. Results: HELP-apheresis reduced the plasma levels of LDL-cholesterol, lipoprotein (a) and C-reactive protein by 48% (p < 0.001), fibrinogen by 42% (p = 0.02), plasma viscosity by 14% (p = 0.004) and erythrocyte aggregation by 28% (p < 0.02). Osmolality (<1%) and hematocrit (<2%) remained stable. A single apheresis treatment increased median corrected rest flow by 17.5% (p = 0.007) and median hyperemic flow by 27% (p = 0.02). Median coronary flow reserve increased by 8.1% (p = 0.09). Hyperemic flow after adenosine infusion increased plasma vascular endothelial growth factor levels only before HELP-apheresis (+60%), indicating better ischemic tolerance after apheresis (p = 0.01). Conclusions: Myocardial perfusion in transplanted hearts increases significantly after single HELP-apheresis treatment. The present study is only a proof of concept, providing complementary evidence to clinical long-term studies showing that cholesterol reduction either with statins and/or apheresis improves heart transplant outcome.