Hypoattenuated leaflet thickening and leaflet thrombosis following ...

Hypoattenuated leaflet thickening and leaflet thrombosis following transcatheter aortic valve replacement (HALT in TAVR)

Dr Hashrul Rashid, Monash University

2019 Health Professional Scholarship

Years funded: 2020-2022

Severe aortic stenosis is stiffening of the aortic valve, which may lead to heart failure and death. It can be treated with transcatheter aortic valve replacement (TAVR), usually through deploying a valve through the groin artery. Unfortunately, this valve may develop clot(s) at any time after insertion, with an incidence of 15 to 40% and may increase the risk of stroke.

Echocardiography has been used to detect valve clots, but imaging artefact may impair visualisation of these clots. Computed tomography (CT) is highly accurate in detecting small sized clots on valve leaflets but it is a limited resource and it comes with the risk of contrast-related kidney impairment and radiation exposure. This research aims to predict which patients may develop valve clots following TAVR.

This allows

1. appropriate selection of patients requiring investigations,
2. reduction of unnecessary tests,
3. reduce the risks of regular CT to patients and
4. prevent stroke events.

One potential method to predict this is by measuring blood clotting markers, which is the first aim of the study. Blood samples are collected before the TAVR procedure, at discharge and at one month. Patients with valve clots may have higher levels of clotting markers such as D-dimer, similarly seen in patients with other clotting conditions. The shape of valve prosthesis may play a role in valve clots. Simulation studies have demonstrated abnormally shaped valve leads to leaflet damage which may lead to clot formation, but it has not been clearly demonstrated in real-world studies. With sophisticated 4-dimensional CT, our second aim is to determine the relationship between the valve's shape with developing valve clots.