Raichlin, Eugenia

BACKGROUND: The immunologic risk associated with preformed donor-specific allo-antibodies (DSA) against human leukocyte antigens (HLA) in heart transplant (HTX) recipients is unclear. The goal of this study was to evaluate potential role of DSA on the progression of cardiac allograft vasculopathy (CAV) in HTX recipients. METHODS: The presence of DSA against HLA was evaluated using solid phase Single Antigen Bead assay (One Lambda, Inc., Canoga Park, CA; Luminex platform) before transplant in 35 HTX recipients. Using alloantibody specification analysis, 11% (4/35) and 20% (7/35) had DSA against donor Class I and II HLA respectively including the one patient who had both (DSA I & II+) . 71% (25/35) of patients had no demonstrable DSA (DSA-). All patients had negative cytotoxicity cross match. Baseline three-dimensional intravascular ultrasound studies (3D IVUS) were performed at 1.0 [0.18, 1.4] year after transplant. Follow up 3D IVUS exams were performed 0.92 [0.85, 1.04] years after the baseline exam. RESULTS: The increase in mean plaque (media and intima) volume (PV) was accelerated in the DSA II+ group as compared to the DSA- group (0.87±1.9 mm (3)/mm vs. 0.16±1.8 mm (3)/mm) but the vessel volume index (follow up vessel volume/ baseline vessel volume) was similar between groups (1.08±0.5 vs. 1.09± 0.4; p=0.9). Plaque index (PI) (PV/vessel volume x 100 [%]) increased significantly in the DSA II+ group (17.9±6.3%) but not in the DSA- group (-13.6±13.2%, P=0.02). None of these values were significant in the DSA I+ only group. Treatment with Sirolimus did not affect PI progression between the DSA II+ and DSA- groups (PI progression: 15.9±8.7% vs. -11.7±7.1%, P=0.03). Age, gender, lipid and uric acid levels, prevalence of diabetes, ischemic time, time between IVUS examinations, the use of steroids, mycophenolate vs. azathioprine or calcineurin inhibitors vs. sirolimus were not different between the groups (P>0.4 for all). CONCLUSIONS: Heart transplant recipients with clearly defined anti-Class II DSA are at risk for accelerated cardiac allograft vasculopathy. Whether interventions to minimize the risk of DSA such as virtual crossmatch, desensitization and complement inhibition will retard CAV remains to be proven.

Background— We retrospectively analyzed the potential of sirolimus as a primary immunosuppressant in the long-term attenuation of cardiac allograft vasculopathy progression and the effects on cardiac-related morbidity and mortality. Methods and Results— Forty-five cardiac transplant recipients were converted to sirolimus 1.2 years (0.2, 4.0) after transplantation with complete calcineurin inhibitor withdrawal. Fifty-eight control subjects 2.0 years (0.2, 6.5 years) from transplantation were maintained on calcineurin inhibitors. Age, sex, ejection fraction, and time from transplantation to baseline intravascular ultrasound study were not different ( P >0.2 for all) between the groups; neither were secondary immunosuppressants and use of steroids. Three-dimensional intravascular ultrasound studies were performed at baseline and 3.1 years (1.3, 4.6 years) later. Plaque index progression (plaque volume/vessel volume) was attenuated in the sirolimus group (0.7±10.5% versus 9.3±10.8%; P =0.0003) owing to reduced plaque volume in patients converted to sirolimus early (<2 years) after transplantation ( P =0.05) and improved positive vascular remodeling ( P =0.01) in patients analyzed late (>2 years) after transplantation. Outcome analysis in 160 consecutive patients maintained on 1 therapy was performed regardless of performance of intravascular ultrasound examinations. Five-year survival was improved with sirolimus (97.4±1.8% versus 81.8±4.9%; P =0.006), as was freedom from cardiac-related events (93.6±3.2% versus 76.9±5.5%; P =0.002). Conclusions— Substituting calcineurin inhibitor with sirolimus as primary immunosuppressant attenuates long-term cardiac allograft vasculopathy progression and may improve long-term allograft survival owing to favorable coronary remodeling. Because of the lack of randomization and retrospective nature of our analysis, the differences in outcome should be interpreted cautiously, and prospective clinical trials are required.

Background— Endothelin (ET-1) is one of the most potent vasoconstrictors and plays a seminal role in the pathogenesis of atherosclerosis. The present study was designed to test the hypothesis that long-term treatment with an endothelin-A (ET A ) receptor antagonist improves coronary endothelial function in patients with early coronary atherosclerosis. Methods and Results— Forty-seven patients with multiple cardiovascular risk factors, nonobstructive coronary artery disease, and coronary endothelial dysfunction were randomized in a double-blind manner to either the ET A receptor antagonist atrasentan (10 mg) or placebo for 6 months. Coronary endothelium-dependent vasodilation was examined by infusing acetylcholine (10 −6 to 10 −4 mol/L) in the left anterior descending coronary artery. N G -monomethyl- l -arginine was administered to a subgroup of patients. Endothelium-independent coronary flow reserve was examined by use of intracoronary adenosine and nitroglycerin. Baseline characteristics and incidence of adverse effects were similar between the 2 groups. There was a significant improvement in percent change of coronary blood flow in response to acetylcholine at 6 months from baseline in the atrasentan group compared with the placebo group (39.67%, 95% confidence interval 23.23% to 68.21%, versus −2.22%, 95% confidence interval −27.37% to 15.28%; P <0.001). No significant difference in the percent change of coronary artery diameter or change in coronary flow reserve was demonstrated. Coronary blood flow, coronary artery diameter, and the effect of N G -monomethyl- l -arginine were similar between the groups at baseline and at 6 months. Conclusions— This study demonstrates that 6-month treatment with atrasentan improves coronary microvascular endothelial function and supports the role of the endogenous endothelin system in the regulation of endothelial function in early atherosclerosis in humans. Clinical Trial Registration Information— URL: http://www.clinicaltrials.gov. Unique identifier: NCT00271492.

Endothelin plays an important role in the pathogenesis of atherosclerosis. The aim of the study was to evaluate the safety and hemodynamic and metabolic responses to 6 months treatment with atrasentan, the selective endothelin-A receptor antagonist. Seventy-two patients with multiple cardiovascular risk factors and nonobstructive coronary artery disease on coronary angiogram were randomly assigned in a double-blind manner to atrasentan or placebo. Mean aortic blood pressure decreased from 92±10 to 80±10 mm Hg ( P <0.001) in the atrasentan group and did not change in the placebo group (93±10 and 92±11 mm Hg; P =0.84). The difference between the groups was significant ( P <0.001). No effect on heart rate was observed. In a subgroup of patients not treated with angiotensin-converting enzyme inhibitor, creatinine level decreased in the atrasentan versus the placebo group ( P =0.011). Fasting glucose ( P =0.026), glycosylated hemoglobin level ( P =0.041), triglyceride l ( P =0.013), lipoprotein-A ( P =0.046), and uric acid levels ( P =0.048) decreased significantly in the atrasentan group compared with the placebo group. No progression of angiographic coronary disease was observed. The most common adverse effects with atrasentan were nasal stuffiness, headache, and edema. In conclusion, 6 months of treatment with atrasentan results in a reduction of blood pressure and improvement in glucose and lipid metabolism. These findings suggest the beneficial role of atrasentan in the treatment of hypertension and metabolic syndrome.

Background— We investigated the potential of conversion to sirolimus (SRL) as a primary immunosuppressant in attenuating cardiac allograft vasculopathy progression. Methods and Results— Twenty-nine cardiac transplant recipients were converted to SRL 3.8±3.4 years after transplantation with complete calcineurin inhibitor (CNI) withdrawal. Secondary immunosuppressants (azathioprine or mycophenolate) and steroids remained unchanged. Forty patients (controls) 4.8±4.0 years from transplantation were maintained on CNIs. Three-dimensional intravascular ultrasound studies were performed at baseline and 12.1±2.6 months later. Mean plaque (media and intima) volume (PV) and plaque index (PI) (PV/vessel volume percent) increased significantly in the CNI group (1.28±2.86 mm 3 /mm, P =0.004; and 6±8%, P =0.0001) but not in the SRL group (0.1±1.13 mm 3 /mm, P =0.63; and 0.1±8%, P =0.94). In patients enrolled within 2 years after transplantation, the increases in PV (0.06±1.06 versus 1.77±1.65 mm 3 /mm; P =0.0081) and PI (0±9% versus 10±8%; P =0.0145) were smaller in the SRL group (n=11) than in the CNI (n=12) group. In patients enrolled ≥2 years after transplantation, the increase in PI was less in the SRL group compared with the CNI group (0.1±6.5% versus 5±8%; P =0.033), but changes in PV did not differ significantly. Treatment with azathioprine or mycophenolate did not affect PV or PI in either the SRL group (PV: 0.22±0.66 versus 0.05±1.45 mm 3 /mm, P =0.46; PI: 1.5±6% versus −1.6±8.5%, P =0.29) or the CNI group (PV: 1.42±1.39 versus 1.06±2.28 mm 3 /mm, P =0.49; PI: 7.8±8.7% versus 4.8±7.3%, P =0.23). Conclusions— Substituting CNI with SRL as primary immunosuppression attenuates cardiac allograft vasculopathy progression.