Intermittent Claudication and Asymptomatic Peripheral Arterial Disease

Predicting outcomes following lower extremity open revascularization using machine learning

Lower extremity open revascularization is a treatment option for peripheral artery disease that carries significant peri-operative risks; however, outcome prediction tools remain limited. Using machine learning (ML), we developed automated algorithms that predict 30-day outcomes following lower extremity open revascularization. The National Surgical Quality Improvement Program targeted vascular database was used to identify patients who underwent lower extremity open revascularization for chronic atherosclerotic disease between 2011 and 2021. Input features included 37 pre-operative demographic/clinical variables. The primary outcome was 30-day major adverse limb event (MALE; composite of untreated loss of patency, major reintervention, or major amputation) or death. Our data were split into training (70%) and test (30%) sets. Using tenfold cross-validation, we trained 6 ML models. Overall, 24,309 patients were included. The primary outcome of 30-day MALE or death occurred in 2349 (9.3%) patients. Our best performing prediction model was XGBoost, achieving an area under the receiver operating characteristic curve (95% CI) of 0.93 (0.92-0.94). The calibration plot showed good agreement between predicted and observed event probabilities with a Brier score of 0.08. Our ML algorithm has potential for important utility in guiding risk mitigation strategies for patients being considered for lower extremity open revascularization to improve outcomes.

Exercise Training for Patients With Peripheral Arterial Occlusive Disease

BACKGROUND

One-third of all persons with peripheral arterial occlusive disease (PAOD) suffer from intermittent claudication. Exercise training under appropriate supervision is recommended in the pertinent guidelines, but physicians order it too rarely, and so-called vascular exercise groups are not available everywhere. This situation needs improvement in view of the impor - tance of walking ability and cardiorespiratory fitness for patients' quality of life and long-term disease outcome.

METHODS

We review the scientific evidence on exercise training and on ways to lower barriers to the ordering of exercise training and to patient participation, on the basis of pertinent articles retrieved by a search of PubMed and in specialized sports science journals.

RESULTS

10 meta-analyses, 12 randomized controlled trials (RCTs), and 7 cohort studies were considered for this review. Largescale cohort studies have shown that exercise is associated with a lower risk of death (relative risk 0.65-0.78 after 12 months of exercise training, compared to an inactive lifestyle). Exercise training also improves the maximal walking distance by a mean of 136 m (training at home) or 180-310 m (supervised training). An additional improvement by a mean of 282 m can be expected from a combination of exercise training and endovascular revascularization. Further behavior-modifying interventions, such as goal-setting, planning, and feedback, increase both the maximum walking distance and the weekly duration of exercise.

CONCLUSION

Exercise improves walking ability and lowers mortality. To attract patients with intermittent claudication to exercise training, a broad assortment of analog, digital and telemetric tools and a dense network of vascular exercise groups should be made available, along with regular contact between physicians and patients.

Das große Verbesserungspotenzial in der multimodalen Basisbehandlung der peripheren arteriellen Verschlusskrankheit (pAVK): ein Aufruf zum flächendeckenden Ausbau der pAVK-Gehtrainingsgruppen in Deutschland

Das Gehtraining gehört zu den wichtigsten Säulen der Behandlung der peripheren arteriellen Verschlusskrankheit (pAVK). Das Gehtraining in Gruppen unter Anleitung ist dabei besonders effektiv. In Deutschland ist ein flächendeckendes Angebot von Gehtrainingsgruppen nicht verfügbar. Von der Deutschen Gesellschaft für Gefäßchirurgie und Gefäßmedizin (DGG e. V.), vertreten durch die Kommission „pAVK und diabetischer Fuß“ wurde daher eine Kampagne zur bundesweiten Förderung des Aufbaus von lokalen Gehtrainingsgruppen gestartet. In diesem Artikel wird an Gefäßmediziner appelliert, bei sich vor Ort die Gehtrainingsgruppen auszubauen und mitzugestalten. Die Wege zum Ausbau solcher Gehtrainingsgruppen werden beschrieben.

Primärtherapie der Claudicatio intermittens – Anspruch und Wirklichkeit

Die narrative Übersichtsarbeit fasst die Studienlage zum Thema Gehtraining bei Patienten mit Claudicatio intermittens (CI) zusammen. Eindringlich wird auf die evidenzbasierten Leitlinienempfehlungen und die dahinterstehenden Studien eingegangen. Aspekte zum angiomorphologischen Befund, zu Patientenadhärenz, Langzeitwirkung, Studienqualität und ihre Vergleichbarkeit werden diskutiert. Der Problematik in der Versorgungsrealität mit Abweichungen von den Leitlinien und der oftmals invasiven Erstlinientherapie des PAVK-IIb-Patienten werden besondere Bedeutung geschenkt. Dabei wird die Rolle des Rehasports und die gesundheitspolititsche Bedeutung von Gehtraining in Deutschland erörtert. Gründe für die fehlende Leitlinientreue und deren Umsetzung im Gesundheitssystem werden analysiert. Dementsprechend werden Handlungsempfehlungen, in Anlehnung an internationale Erfahrungen (Niederlande, Dänemark), zur Besserung der Situation in Deutschland formuliert.

CT-based fractional flow reserve: development and expanded application

Computations of fractional flow reserve, based on CT coronary angiography and computational fluid dynamics (CT-based FFR) to assess the severity of coronary artery stenosis, was introduced around a decade ago and is now one of the most successful applications of computational fluid dynamic modelling in clinical practice. Although the mathematical modelling framework behind this approach and the clinical operational model vary, its clinical efficacy has been demonstrated well in general. In this review, technical elements behind CT-based FFR computation are summarised with some key assumptions and challenges. Examples of these challenges include the complexity of the model (such as blood viscosity and vessel wall compliance modelling), whose impact has been debated in the research. Efforts made to address the practical challenge of processing time are also reviewed. Then, further application areas—myocardial bridge, renal stenosis and lower limb stenosis—are discussed along with specific challenges expected in these areas.