P6258Direct oral anticoagulants in non-valvular atrial fibrillation: accuracy of traditional bleeding scores in the elderly

Background

Due to the fear of increased risk of bleeding, anticoagulation treatment is underutilized in the prevention of stroke in elderly patients with non-valvular atrial fibrillation (NVAF). Although direct oral anticoagulants (DOAC) are safer than VKA, still little is known about the risk factors associated with bleeding in elderly patients treated with DOAC. Furthermore, it is still uncertain whether the risk scores that are currently used can serve to effectively identify higher bleeding risk in elderly subjects.

Purpose

The aim of this study was to identify predictors of bleeding in a cohort of elderly people affected by NVAF treated with DOAC, and to evaluate the accuracy of risk scores for bleeding used at present.

Methods

Data on outpatients aged ≥75 years, naïve for DOAC therapy, who started therapy with Dabigatran, Rivaroxaban, Apixaban or Edoxaban for the prevention of thromboembolism during FANV were analyzed. HASBLED, ATRIA, OBRI and ORBIT scores were calculated for each patient. Patients had follow-up for 12 months during which deaths, therapy discontinuation and adverse events such as thromboembolism and bleeding were reported. Potential predictors of bleeding and the predictive value of each bleeding score were tested using univariate Cox regression; testing accuracy was evaluated using ROC curves.

Results

A total of 291 patients (52.9% female, mean age 82.85±5.18 years) had a median follow-up time of 11 (10–12) months. The incidence rate of major bleeding was 4.7 per 100 patient-years, the rate of intracranial bleeding was 0.4 per 100 patient-years. Patients who had major bleeding were more often affected by heart failure (63.6% vs 25%; p=0.009) and thrombocytopenia (36.4% vs 7.4%; p=0,009). However in the multivariate analysis only heart failure remained statistically associated with major bleeding (HR 3.83, 95% CI 1.06–13.85; p=0.041). None of tested bleeding risk scores was able to predict major bleeding in our cohort. HASBLED and ORBIT scores were able to predict major and non-major clinically relevant bleeding (HR 1.32; 95% CI 1.01–1.71; p=0.042 and HR 1.20; 95% CI 1.00- 1.43; p=0.046); only the ORBIT score was found to be statistically significant, but with weak discriminatory power at ROC curves (AUC 0.59; 95% CI 0.51–0.68; p=0.041).

Conclusions

In our cohort of elderly patients aged 75 or older, anticoagulated for NVAF, heart failure history was the only effective predictor of major bleeding risk during DOAC treatment. None of the bleeding risk scores used currently have demonstrated a good discriminatory power in our cohort. As predictive factors of bleedings in DOAC-treated patients may not be the same as those for VKA-treated patients and those in elderly may also be differ in younger people, it calls for more investigation on the topic.

NOP Receptor Ligands and Parkinson's Disease

Nociceptin/Orphanin FQ (N/OFQ) and its NOP receptor are highly expressed in motor areas of the rodent, nonhuman, and human primate brain, such as primary motor cortex, thalamus, globus pallidus, striatum, and substantia nigra. Endogenous N/OFQ negatively regulates motor behavior and dopamine transmission through NOP receptors expressed by dopaminergic neurons of the substantia nigra compacta. Consistent with the existence of an N/OFQ tone over dopaminergic transmission, blockade of NOP receptor antagonists increases striatal dopamine release. In this chapter, we will review the evidence linking the N/OFQ-NOP receptor system to Parkinson's disease (PD). We will first discuss data showing that the central N/OFQ-NOP receptor system undergoes plastic changes in different basal ganglia nuclei following dopamine depletion. Then we will show that NOP receptor antagonists relieve motor deficits in different rodent and nonhuman primate models of PD. Mechanistically, NOP receptor blockade in substantia nigra reticulata results in rebalancing of the inhibitory GABAergic and excitatory glutamatergic inputs impinging on nigro-thalamic GABAergic neurons, leading to thalamic disinhibition. We will also present data showing that, in addition to motor symptoms, N/OFQ also plays a role in the parkinsonian neurodegeneration. In fact, NOP receptor antagonists possess neuroprotective/neurorescue properties in in vitro and in vivo models of PD.

G2019S LRRK2 mutation facilitates α-synuclein neuropathology in aged mice

Fibrillization of α-synuclein is instrumental for the development of Parkinson's disease (PD), thus modulating this process can have profound impact on disease initiation/progression. Here, the impact of the p.G2019S mutation of leucine-rich repeat kinase 2 (LRRK2), which is most frequently associated with familial and sporadic PD, on α-synuclein pathology was investigated. G2019S knock-in mice and wild-type controls were injected with a recombinant adeno-associated viral vector serotype 2/9 (AAV2/9) overexpressing human mutant p.A53T α-synuclein (AAV2/9-hα-syn). Control animals were injected with AAV2/9 carrying green fluorescent protein. Motor behavior, transgene expression, α-syn and pSer129 α-syn load, number of nigral dopamine neurons and density of striatal dopaminergic terminals were evaluated. To investigate the effect of aging, experiments were performed in 3- and 12-month-old mice, evaluated 20 and 12 weeks after virus injection, respectively. hα-syn overexpression induced progressive motor deficits, loss of nigral dopaminergic neurons and striatal terminals, and appearance of proteinase K-resistant aggregates of pSer129 α-syn in both young and old mice. Although no genotype difference was observed in 3-month-old mice, degeneration of nigral dopaminergic neurons was higher in 12-month-old G2019S knock-in mice compared with age-matched wild-type controls (-55% vs -39%, respectively). Consistently, a two-fold higher load of pSer129 α-syn aggregates was found in 12-month-old G2019S knock-in mice. We conclude that G2019S LRRK2 facilitates α-synucleinopathy and degeneration of nigral dopaminergic neurons, and that aging is a major determinant of this effect.