A new metric enabling an exact hypergraph model for the communication volume in distributed-memory parallel applications

A hypergraph model for mapping applications with an all-neighbor communication pattern to distributed-memory computers is proposed, which originated in finite element triangulations. Rather than approximating the communication volume for linear algebra operations, this new model represents the communication volume exactly. To this end, a hypergraph partitioning problem is formulated where the objective function involves a new metric. This metric, the kðk 1Þ-metric, accurately models the communication volume for an all-neighbor communication pattern occurring in a concrete finite element application. It is a member of a more general class of metrics, which also contains more widely used metrics, such as the cut–net and the ðk 1Þ-metric. In addition, we develop a heuristic to minimize the communication volume in the new kðk 1Þ-metric. For the solution of several real-world finite element problems, experimental results based on this new heuristic demonstrate a small reduction in communication volume compared to a standard graph partitioner and do not show significant reductions in communication volume compared to a hypergraph partitioner using the common ðk 1Þ-metric. However, for this set of problems, the new approach does reduce actual communication times. As a by-product, we observe that it also tends to reduce the number of messages. Furthermore, the new approach dramatically reduces the communication volume for a set of sparse matrix problems that are more irregularly-structured than finite element problems

Altlastenbericht 1. Fortschreibung

With 1 mapTIB Hannover RO 8421(1989,1) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Congestion patterns in severe tricuspid regurgitation and transcatheter treatment: Insights from a multicentre registry.

AIMS While invasively determined congestion holds mechanistic and prognostic significance in acute heart failure (HF), its role in patients with tricuspid regurgitation (TR)-related right- heart failure (HF) undergoing transcatheter tricuspid valve intervention (TTVI) is less well established. A comprehensive understanding of congestion patterns might aid in procedural planning, risk stratification, and the identification of patients who may benefit from adjunctive therapies before undergoing TTVI. The aim of this study was to investigate the role of congestion patterns in patients with severe TR and its implications for TTVI. METHODS AND RESULTS Within a multicentre, international TTVI registry, 813 patients underwent right heart catheterization (RHC) prior to TTVI and were followed up to 24 months. The median age was 80 (interquartile range 76-83) years and 54% were women. Both mean right atrial pressure (RAP) and pulmonary capillary wedge pressure (PCWP) were associated with 2-year mortality on Cox regression analyses with Youden index-derived cut-offs of 17 mmHg and 19 mmHg, respectively (p < 0.01 for all). However, RAP emerged as an independent predictor of outcomes following multivariable adjustments. Pre-interventionally, 42% of patients were classified as euvolaemic (RAP <17 mmHg, PCWP <19 mmHg), 23% as having left-sided congestion (RAP <17 mmHg, PCWP ≥19 mmHg), 8% as right-sided congestion (RAP ≥17 mmHg, PCWP <19 mmHg), and 27% as bilateral congestion (RAP ≥17 mmHg, PCWP ≥19 mmHg). Patients with right-sided or bilateral congestion had the lowest procedural success rates and shortest survival times. Congestion patterns allowed for discerning specific patient's physiology and specifying prognostic implications of right ventricular to pulmonary artery coupling surrogates. CONCLUSION In this large cohort of invasively characterized patients undergoing TTVI, congestion patterns involving right-sided congestion were associated with low procedural success and higher mortality rates after TTVI. Whether pre-interventional reduction of right-sided congestion can improve outcomes after TTVI should be established in dedicated studies

Sex-Related Differences in Clinical Characteristics and Outcome Prediction Among Patients Undergoing Transcatheter Tricuspid Valve Intervention.

BACKGROUND Men and women differ regarding comorbidities, pathophysiology, and the progression of valvular heart diseases. OBJECTIVES This study sought to assess sex-related differences regarding clinical characteristics and the outcome of patients with severe tricuspid regurgitation (TR) undergoing transcatheter tricuspid valve intervention (TTVI). METHODS All 702 patients in this multicenter study underwent TTVI for severe TR. The primary outcome was 2-year all-cause mortality. RESULTS Among 386 women and 316 men in this study, men were more often diagnosed with coronary artery disease (52.9% in men vs 35.5% in women; P = 5.6 × 10-6). Subsequently, the underlying etiology for TR in men was predominantly secondary ventricular (64.6% in men vs 50.0% in women; P = 1.4 × 10-4), whereas women more often presented with secondary atrial etiology (41.7% in women vs 24.4% in men, P = 2.0 × 10-6). Notably, 2-year survival after TTVI was similar in women and men (69.9% in women vs 63.7% in men; P = 0.144). Multivariate regression analysis identified dyspnea expressed as New York Heart Association functional class, tricuspid annulus plane systolic excursion (TAPSE), and mean pulmonary artery pressure (mPAP) as independent predictors for 2-year mortality. The prognostic significance of TAPSE and mPAP differed between sexes. Consequently, we looked at right ventricular-pulmonary arterial coupling expressed as TAPSE/mPAP and identified sex-specific thresholds to best predict survival; women with a TAPSE/mPAP ratio <0.612 mm/mm Hg displayed a 3.43-fold increased HR for 2-year mortality (P < 0.001), whereas men with a TAPSE/mPAP ratio <0.434 mm/mm Hg displayed a 2.05-fold increased HR for 2-year mortality (P = 0.001). CONCLUSIONS Even though men and women differ in the etiology of TR, both sexes show similar survival rates after TTVI. The TAPSE/mPAP ratio can improve prognostication after TTVI, and sex-specific thresholds should be applied to guide future patient selection

Epiphenomenon or Prognostically Relevant Interventional Target? A Novel Proportionality Framework for Severe Tricuspid Regurgitation

Background Tricuspid regurgitation (TR) frequently develops in patients with long‐standing pulmonary hypertension, and both pathologies are associated with increased morbidity and mortality. This study aimed to improve prognostic assessment in patients with severe TR undergoing transcatheter tricuspid valve intervention (TTVI) by relating the extent of TR to pulmonary artery pressures. Methods and Results In this multicenter study, we included 533 patients undergoing TTVI for moderate‐to‐severe or severe TR. The proportionality framework was based on the ratio of tricuspid valve effective regurgitant orifice area to mean pulmonary artery pressure. An optimal threshold for tricuspid valve effective regurgitant orifice area/mean pulmonary artery pressure ratio was derived on 353 patients with regard to 2‐year all‐cause mortality and externally validated on 180 patients. Patients with a tricuspid valve effective regurgitant orifice area/mean pulmonary artery pressure ratio ≤1.25 mm2/mm Hg (defining proportionate TR) featured significantly lower 2‐year survival rates after TTVI than patients with disproportionate TR (56.6% versus 69.6%; P=0.005). In contrast with patients with disproportionate TR (n=398), patients with proportionate TR (n=135) showed more pronounced mPAP levels (37.9±9.06 mm Hg versus 27.9±8.17 mm Hg; P<2.2×10−16) and more severely impaired right ventricular function (tricuspid annular plane systolic excursion: 16.0±4.11 versus 17.0±4.64 mm; P=0.012). Moreover, tricuspid valve effective regurgitant orifice area was smaller in patients with proportionate TR when compared with disproportionate TR (0.350±0.105 cm2 versus 0.770±0.432 cm2; P<2.2×10−16). Importantly, proportionate TR remained a significant predictor for 2‐year mortality after adjusting for demographic and clinical variables (hazard ratio, 1.7; P=0.006). Conclusions The proposed proportionality framework promises to improve future risk stratification and clinical decision‐making by identifying patients who benefit the most from TTVI (disproportionate TR). As a next step, randomized controlled studies with a conservative treatment arm are needed to quantify the net benefit of TTVI in patients with proportionate TR