Development and application of a physiological tool to predict the haemodynamic impact of coronary artery stenting

Abstract

Coronary angioplasty is a commonly used therapy to remove stenoses in patients with chronic stable angina. Although a successful procedure, there remain both the short-term (stent thrombosis and vessel injury) and long-term risks (late stent thrombosis and significant in-stent restenosis) such that indiscriminate use of stenting can be deleterious. A considerable body of evidence suggests clinical outcomes are improved when stenting is performed using invasive coronary physiology; if stenoses cause ischaemia revascularisation is preferential to deferment, while non-ischaemic stenoses may be treated with medical therapy and observation. Successfully treated vessels are less likely to have major cardiovascular events and patient events are improved. However, there remains no good way of readily and practically predicting whether placing a stent will be successful with normalisation of abnormal coronary physiology. Furthermore, there remains no good parameter to delineate the length of a stenoses and the amount of stenting required to achieve an optimal haemodynamic result. The behaviour of coronary physiology after coronary intervention remains poorly described, particularly in the resting state. Furthermore, human coronary disease is often complex with many coronary stenoses present. This confounds our physiological assessment of a given stenosis and contributes to the poor utilisation of physiological technologies in the patients. In this thesis, I apply phasic assessment throughout the cardiac cycle to describe the behaviour of coronary physiology in humans who undergo assessment and intervention in the catheter laboratory. The behaviour of coronary pressure, flow velocity and resistance will be assessed. I will assess how these parameters change after coronary intervention to develop models of predicting the change in coronary flow and pressure. I will then apply these models to a novel approach that allows assessment of physiological stenosis length, the identification of haemodynamic impact imposed by a single stenosis in diffusely diseased and tandem stenoses. The aim is to produce a new clinical tool that can be readily used in the clinical assessment of challenging coronary disease.