Urban air mobility requires safe and efficient airspace management, as well as effective path planning and decision-making capabilities to enable access to the urban airspace, which is predicted to be very densely populated. This paper tackles the problem of strategic and tactical path planning by presenting a framework specifically designed for accounting for several constraints and issues of the urban environment. Multi-objective and multi-constraint planner algorithms are developed to this aim, along with an innovative method for information simplification and manipulation. Navigation-aware and optimized trajectories were retrieved from the strategic approach. Tactical path planning was developed using three approaches that react differently to unpredicted conditions. The entire strategic–tactical pipeline was tested in two real-world use cases, representing common missions in urban environments, such as medical delivery and short-range air taxi. The results demonstrate the effectiveness of the proposed methodology in generating the strategic path and show the different outcomes of the proposed tactical approaches, thus highlighting their advantages and drawbacks.
Background Monotherapy with P2Y12 inhibitors (P2Y12i) is emerging as alternative strategy to dual antiplatelet therapy (DAPT) after percutaneous coronary intervention (PCI). However, early withdrawal of aspirin as part of P2Y12i monotherapy regimens may pose concerns in high-risk patients, such as those undergoing complex PCI. Purpose To evaluate the efficacy and safety of P2Y12i monotherapy after a short course of DAPT (1- to 3-month) compared with standard DAPT (≥12-month) according to PCI complexity. Methods We performed a meta-analysis of randomized trials using random effects models to combine hazard ratios (HRs) with 95% confidence intervals (CIs). No restrictions were applied to the type of P2Y12 receptor inhibitor (clopidogrel, prasugrel, or ticagrelor) or to the definition of complex PCI. Within-trial interactions were pooled to estimate heterogeneity between complex and noncomplex PCI strata. The study protocol was registered in the PROSPERO (CRD42021291027). Results We screened 7,502 unique citations, of which 2,948 were screened at title and abstract level and 576 were judged potentially eligible for full-text assessment. We included in the analysis five trials (1–5) enrolling 31,627 patients, of whom 8,328 (26.3%) underwent complex PCI; characteristics of trials and patient populations are summarized in Table 1. Risk estimates for efficacy and safety outcomes associated with P2Y12i monotherapy and standard DAPT across studies included in the analysis, stratified by complex and noncomplex PCI, are reported in Figure 1. P2Y12i monotherapy compared with standard DAPT was associated with a similar risk of all-cause death, stent thrombosis, and stroke, with no evidence for interaction between complex and noncomplex PCI. We found heterogeneity in the treatment effect of P2Y12i monotherapy vs. standard DAPT with respect to myocardial infarction (P-interaction=0.027). Compared with standard DAPT, P2Y12i monotherapy decreased the risk of myocardial infarction in complex PCI (HR 0.77, 95% CI 0.60–0.99, P=0.042), but not in noncomplex PCI patients (HR 1.09, 95% CI 0.90–1.30, P=0.382). The risk of major bleeding was significantly reduced by P2Y12i monotherapy with a consistent treatment effect (P-interaction=0.699) in both complex and noncomplex PCI strata. Conclusions Patients undergoing complex PCI may derive more benefit and less harm from P2Y12i monotherapy after early aspirin withdrawal compared with standard DAPT, resulting in decreased risks of myocardial infarction and bleeding. Funding Acknowledgement Type of funding sources: None.
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