Pereira, Naveen L.

Background Pregnancies may result in antibodies against HLA, a risk factor for antibody-mediated rejection (AMR) and subsequent cardiac allograft vasculopathy (CAV) after heart transplantation (HTx). The aim of this study was to evaluate sex differences in the incidence of AMR events and subsequent risk of CAV among HTx recipients. Methods The study comprised 160 patients (51 [32%] women) who underwent HTx in 2008 to 2014. The cumulative effect of AMR events was calculated by AMR score (sum of myocardial biopsy grading divided by number of biopsies taken during 3 years post-HTx). Results Females had higher levels of anti-HLA I antibodies pre-HTx compared to males which was associated with a history of pregnancies, total number of children and with a higher AMR score at 6 months post-HTx (P < 0.05). Women demonstrated a significant increase in the total incidence of AMR events (27 vs. 7%, P = 0.001) and in AMR scores at 6, 12, 24 and 36 months post-HTx compared to men (P < 0.05). There were no differences in cellular rejection between the groups. A history of AMR events was associated with a significantly increased risk of severe CAV onset (hazard ratio, 7.0; 95% confidence interval, 1.5-31.5; P = 0.012). Conclusions Women are at higher risk for AMR post-HTx which subsequently increases their risk for CAV. Females recipients may benefit from closer surveillance to identify AMR at an earlier stage post-HTx, and targeted immunosuppressive therapy to attenuate the development of CAV.

Background— The goal of this study was to identify genetic determinants of plasma N-terminal proatrial natriuretic peptide (NT-proANP) in the general community by performing a large-scale genetic association study and to assess its functional significance in in vitro cell studies and on disease susceptibility. Methods and Results— Genotyping was performed across 16 000 genes in 893 randomly selected individuals, with replication in 891 subjects from the community. Plasma NT-proANP 1–98 concentrations were determined using a radioimmunoassay. Thirty-three genome-wide significant single-nucleotide polymorphisms were identified in the MTHFR-CLCN6-NPPA-NPPB locus and were all replicated. To assess the significance, in vitro functional genomic studies and clinical outcomes for carriers of a single-nucleotide polymorphism rs5063 (V32M) located in NPPA that represented the most significant variation in this genetic locus were assessed. The rs5063 variant allozyme in transfected HEK293 cells was decreased to 55±8% of wild-type protein ( P =0.01) as assessed by quantitative western blots. Carriers of rs5063 had lower NT-proANP levels (1427 versus 2291 pmol/L; P <0.001) and higher diastolic blood pressures (75 versus 73 mm Hg; P =0.009) and were at an increased risk of stroke when compared with wild-type subjects independent of age, sex, diabetes mellitus, hypertension, atrial fibrillation, and cholesterol levels (hazard ratio, 1.6; P =0.004). Conclusions— This is the first large-scale genetic association study of circulating NT-proANP levels performed with replication and functional assessment that identified genetic variants in the MTHFR-CLCN6-NPPA-NPPB cluster to be significantly associated with NT-proANP levels. The clinical significance of this variation is related to lower NT-proANP levels, higher blood pressures, and an increased risk of stroke in the general community.

Background— The primary role of natriuretic peptide receptor-3 (NPR3) or NPR-C is in the clearance of natriuretic peptides that play an important role in modulating intravascular volume and vascular tone. Genetic variation in NPR3 has been associated with variation in blood pressure and obesity. Despite the importance of NPR3, sequence variation in the gene has not been addressed using DNA from different ethnic populations. We set out to identify and functionally characterize genetic variation in NPR3 in 3 ethnic groups. Methods and Results— DNA samples from 96 European American, 96 African American, and 96 Han Chinese American healthy subjects were used to resequence NPR3 exons, splice junctions, and flanking regions. We identified 105 polymorphisms, 50 of which were novel, including 8 nonsynonymous single-nucleotide polymorphisms, 7 were novel. Expression constructs were created for the nonsynonymous single-nucleotide polymorphisms. HEK293 cells were transfected with constructs for wild type and variant allozymes; and recombinant proteins were measured by quantitative Western blot analysis. The most significant change in NPR3 protein was observed for the Arg146 variant allozyme, with 20% of wild-type protein, primarily because of autophagy-dependent degradation. NPR3 structural modeling confirmed that the Arg146 variant protein was not compatible with wild-type conformation and could result in protein misfolding or instability. Conclusions— Multiple novel NPR3 genetic polymorphisms were identified in 3 ethnic groups. The Arg146 allozyme displayed a significant decrease in protein quantity because of degradation mediated predominantly by autophagy. This genetic variation could have a significant effect on the metabolism of natriuretic peptides with potential clinical implications.

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.

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.