Citations

Background Cardiac allograft vasculopathy is the leading cause of graft failure and death in heart transplant ( HT x) recipients; however, the association between the etiology of heart failure (ischemic cardiomyopathy [ ICM ] or non‐ ICM ) that led to HT x and progression of c ardiac allograft vasculopathy , and adverse events after HT x has not been explored. Methods and Results We retrospectively included 165 HT x patients, who were followed‐up with at least 2 virtual histology–intravascular ultrasound examinations after HT x, and grouped them as ICM (n=46) or non‐ ICM (n=119). Coronary artery plaque volume was analyzed using virtual histology–intravascular ultrasound, and cardiovascular event data—a composite of myocardial infarction, hospitalization for heart failure and arrhythmia, revascularization, retransplantation, and death including cardiovascular death—were collected from the medical records of all study subjects. ICM patients had significantly higher plaque volume at both first ( P =0.040) and follow‐up ( P =0.015) intravascular ultrasound examinations. After multivariate adjustment for traditional coronary risk factors, ICM was significantly associated with plaque progression (odds ratio 3.10; CI 1.17 to 9.36; P =0.023). Ten‐year cardiovascular event‐free survival was 50% in ICM patients compared with 84% in non‐ ICM patients (log‐rank test P =0.003). In multivariate Cox proportional hazard analysis, ICM was significantly associated with a higher event rate after HT x (hazard ratio 2.02; 95% CI 1.01 to 4.00; P =0.048). Conclusion Our study demonstrates that ischemic etiology of cardiomyopathy prior to HT x may be independently associated with plaque progression and higher event rate after HT x.

AbstractSirolimus is used in heart transplant patients with CAV and CNI‐induced nephropathy. However, little is known regarding the tolerability, rejection rate, and effect on renal function when used empirically in children. We describe our experience with the empiric use of a sirolimus‐based immunosuppressive regimen in pediatric heart transplantation recipients. We reviewed records of patients in whom conversion was attempted to a CNI‐free sirolimus‐based regimen. Rejection episodes and measures of renal function were recorded. We attempted to convert 20 patients, of which 16 were successful. In total, six of 20 patients (30%) experienced adverse effects. Of the 16 converted, four patients converted to sirolimus due to CNI‐induced disease (three nephropathy, one CAV), while 12 patients (mean age 5.5 yr, range 0.1–21 yr; 33% female; 33% with a history of congenital heart disease) were empirically switched to sirolimus at a mean of 2.3 yr after transplant. Follow‐up was available for a mean of 2.5 yr after conversion (range 0.5–8.3 yr). The rate of rejection while taking CNIs was 0.18 rejection episodes per patient‐year (total of five episodes), compared with 0.03 rejection episodes per patient‐year (total of one episode) while on sirolimus. Renal function, in terms of GFR, significantly improved after sirolimus conversion at latest follow‐up (from 86 ± 37 mL/min to 130 ± 49 mL/min, p = 0.02). Here, we demonstrate the potential benefit of empiric use of sirolimus in pediatric heart transplant patients in a CNI‐free regimen. Larger and longer studies are needed to further clarify risks of rejection and adverse effect profiles.

BackgroundEndocardial ablation approaches targeting the retroatrial cardiac ganglia to treat atrial fibrillation (AF) have been proposed. However, the potential value using this approach is unknown. Disruption of the autonomic inputs with orthotropic heart transplant (OHT) provides a unique opportunity to study the effects of autonomic innervation on AF genesis and maintenance. We hypothesized that due to denervation, the risk of postoperative AF would be lower following OHT compared to surgical maze even though both groups get isolation of the pulmonary veins.Methods and ResultsWe reviewed 155 OHTs (mean age 52 ± 11 years, 72% males) and used 1:1 age‐, sex‐, and date‐of‐surgery‐matched two control groups from patients undergoing surgical maze or only coronary artery bypass grafting (CABG). Using conditional logistic regression we compared the odds of AF within 2 weeks following OHT versus controls. Postoperative AF occurred in 10/155 (6.5%) OHT patients. The conditional odds of postoperative AF were lower for OHT as compared to controls (vs maze: odds ratio [OR] 0.27 [95% confidence interval (CI) 0.13–0.57], vs CABG: OR 0.38 [0.17–0.81], P = 0.003; and on additional adjustment for left atrial enlargement, vs maze: OR 0.28 [0.13–0.60], vs CABG: OR 0.14 [0.04–0.47], P = 0.0009).ConclusionsRisk of postoperative AF is significantly lower with OHT as in comparison to surgical maze. As both surgeries entail isolation of the pulmonary veins but only OHT causes disruption of autonomic innervation, this observation supports a mechanistic role of autonomic nervous system in AF. The benefit of targeting the cardiac autonomic system to treat AF needs further investigation.

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— Operative mortality after left ventricular assist device (LVAD) implantation is heavily influenced by patient selection and the technical difficulty of surgery. However, how we treat our patients and LVAD setting may affect the patient outcome beyond this period. We postulated that the presence of echocardiographic variables 1 month after surgery suggesting appropriate degree of LV unloading and an adequate forward flow would be important in determining clinical outcomes after the initial successful LVAD implantation. Methods and Results— We retrospectively analyzed various variables in echocardiographic examinations performed 30 days after LVAD implant in 76 consecutive patients receiving continuous flow device for their association with a compound end point (90-day mortality, readmission for heart failure, or New York Heart Association class III or higher at the end of the 90-day period). The echocardiographic associations examined included estimated LVAD flow, with and without native LV contribution, interventricular septal position, the status of aortic valve opening, an estimated left atrial pressure (ELAP), the mitral flow E-wave deceleration time, and the ratio of deceleration time to E-wave velocity (mitral deceleration index [MDI]). Four patients died during the 30- to 90-day period, 6 patients were readmitted for heart failure, and 25 patients were considered to have New York Heart Association class III or higher at the end of the 90-day period. Variables associated with adverse outcome included increased ELAP (odds ratio, 1.30 [1.16–1.48]; P <0.0001), MDI <2 ms/[cm/s] (odds ratio, 4.4 implantation [1.22–18]; P =0.02) and decreased tricuspid lateral annulus velocity (odds ratio, 0.70 implantation [0.48–0.95]; P =0.02). A leftward deviation of interventricular septum was associated with a worse outcome (odds ratio, 3.03 implantation [1.21–13.3]; P =0.01). Conclusions— Mortality and heart failure after LVAD surgery appear to be predominantly determined by echocardiographic evidence of inefficient unloading of the left ventricle and persistence of right ventricular dysfunction. Increased estimated LA pressure and short MDI are associated with worse mid term outcome. Leftward deviation of the septum is associated with worse outcome as well.

Rationale: Although a cardioprotective function of target of rapamycin (TOR) signaling inhibition has been suggested by pharmacological studies using rapamycin, genetic evidences are still lacking. We explored adult zebrafish as a novel vertebrate model for dissecting signaling pathways in cardiomyopathy. Objective: We generated the second adult zebrafish cardiomyopathy model induced by doxorubicin. By genetically analyzing both the doxorubicin and our previous established anemia-induced cardiomyopathy models, we decipher the functions of TOR signaling in cardiomyopathies of different etiology. Methods and Results: Along the progression of both cardiomyopathy models, we detected dynamic TOR activity at different stages of pathogenesis as well as distinct effects of TOR signaling inhibition. Nevertheless, cardiac enlargement in both models can be effectively attenuated by inhibition of TOR signaling through short-term rapamycin treatment. To assess the long-term effects of TOR reduction, we used a zebrafish target of rapamycin ( ztor ) mutant identified from an insertional mutagenesis screen. We show that TOR haploinsufficiency in the ztor heterozygous fish improved cardiac function, prevented pathological remodeling events, and ultimately reduced mortality in both adult fish models of cardiomyopathy. Mechanistically, these cardioprotective effects are conveyed by the antihypertrophy, antiapoptosis, and proautophagy function of TOR signaling inhibition. Conclusions: Our results prove adult zebrafish as a conserved novel vertebrate model for human cardiomyopathies. Moreover, we provide the first genetic evidence to demonstrate a long-term cardioprotective effect of TOR signaling inhibition on at least 2 cardiomyopathies of distinct etiology, despite dynamic TOR activities during their pathogenesis.

Background— Left ventricular assist device (LVAD) is being increasingly used in patients with end-stage dilated and ischemic cardiomyopathy. There have been no clinical trials addressing the use of LVAD therapy in patients with end-stage heart failure caused by restrictive (RCM) or hypertrophic cardiomyopathy (HCM). The purpose of this study was therefore to analyze the outcome of LVAD therapy in these patients. Methods and Results— Eighty-three patients received continuous axial flow LVAD (Heart mate II, Thoratec, Pleasanton, CA) from February 2007 to May 2010 at our institution. We analyzed the baseline characteristics and surgical and long-term impact of LVAD therapy in 8 patients with RCM or HCM and compared their outcomes with the 75 patients with dilated and ischemic cardiomyopathy. Compared with patients with ischemic or dilated cardiomyopathy, patients with RCM and HCM have significantly smaller left ventricular end-diastolic dimensions (52.5±6 mm versus 68.6±8 mm; P <0.0001) and increased thickness of septal (16 [12, 19] mm versus 10[8.5, 11] mm, P =0.0003) and higher left ventricular ejection fraction (21 [20, 36]% versus 17 [15, 22]%; P =0.0009). We found no difference in early mortality (12.5% versus 9.3%, P =0.57) or length of hospital stay (11 [8, 45] days versus 18.5 [12.2, 27.7] days; P =0.51) between the 2 groups. The right atrial pressure was higher (18 [15, 20] mm Hg versus 12 [9, 15] mm Hg, P =0.03), and pump flow was lower (4.3 [3.8, 4.5] L versus 5.2 [4.7, 5.5] L, P =0.001) after LVAD implantation in patients with RCM and HCM. Central venous catheter related infections were more common in patients with RCM and HCM (87.5% versus 44.5%, P =0.006). There was no difference in the total number of blood units transfused. Median (min, max) follow-up duration after LVAD implantation was 166 [1, 1044] days. The 1-year actuarial survival rate was not different between the 2 groups (87.5% [95% confidence interval, 52.9% to 97.8%] versus 73.2 [95% confidence interval, 60% to 85%]; P =0.77). Conclusions— Our preliminary data show that patients with end-stage heart failure caused by RCM or HCM may benefit from continuous axial flow LVAD therapy. This small study suggests that mortality is comparable with those patients who have dilated or ischemic cardiomyopathy, but right heart failure, prolonged inotropic use, and central venous catheter infections are more common in patients with RCM and HCM who were treated with LVAD. Because of the small numbers the differences should be interpreted cautiously, and prospective clinical trials would be required to recommend this therapy for these patients as bridge to transplantation or destination treatment.

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.

Background— Recent studies in animals suggest that circulating recipient endothelial precursors may participate in the biology of transplant vasculopathy. It is currently unknown whether a similar interaction between recipient endothelial cells and the vessel wall occurs in human subjects undergoing allogeneic cardiac transplantation. Methods and Results— Circulating endothelial cells and endothelial progenitor cells (EPCs) were quantified in 15 cardiac transplantation subjects with and without angiographic evidence of vasculopathy. In a separate series of experiments, the origin (donor or recipient) of transplant plaque endothelial cells was assessed in subjects who had undergone a gender-mismatched cardiac transplantation and had histological evidence of severe vasculopathy at the time of heart explantation. Circulating EPC outgrowth colonies in peripheral blood were significantly reduced in subjects with transplant vasculopathy compared with those without angiographic evidence of disease (EPC colony-forming units [CFU EPC ]: 4.5±1.9 versus 15.1±3.7, P <0.05). There was no significant difference in circulating endothelial cell numbers as defined by day 4 culture acetylated LDL/lectin assay in either of these patient groups. In a separate group of 5 subjects who underwent gender-mismatched cardiac transplantation, there was a significant seeding of recipient endothelial cells (range: 1% to 24% of all luminal endothelial cells) in large-vessel lumen and adventitial microvessel lumen of arteriopathic vessels. No opposite-sex chimeric cells were observed in control gender-matched transplantation scenarios. Conclusions— These data suggest that the human cardiac transplant arteriopathy is associated with reduction in circulating endothelial precursors and with seeding of recipient-derived endothelial cells at the site of plaque development.