Pulmonary Hypertension Complicating Left Heart Disease - Common and Difficult to Treat

Abstract

Pulmonary hypertension due to left heart disease (PHT-LHD) is the most prevalent sub-type of PHT worldwide. Despite being common, this heterogenous group of patients (including those with left sided valvular pathology, reduced left ventricular ejection fraction (LVEF) and left ventricular diastolic dysfunction (LVDD)) is underrepresented in contemporary literature. With a lack of in-depth phenotyping, standardised diagnostic techniques and no clear treatment options despite an adverse prognosis, these patients represent a major unsolved problem in cardiology. The relationships between PHT and the various types of LHDs, in isolation or together, have not been well studied. This is the major focus of this thesis. Chapters 2, 3, 4, 5 and 6 describe the demographic and echocardiographic phenotype of PHT in patients with moderate-severe aortic regurgitation, aortic stenosis and mitral regurgitation, reduced LVEF and LVDD and preserved ejection fraction (pEF) respectively, using data from the National Echo Database of Australia (NEDA). There was a progressively increased risk of mortality as pulmonary pressures increased, even at mild elevations in pulmonary pressure. Chapter 7 directly follows on from this with the aim of addressing why some patients with LVDD and pEF develop raised pulmonary pressures and others don’t. Chapter 8 investigates the prevalence and predictors of RV dysfunction in cohort of patients with severe aortic stenosis who were undergoing TAVI. Clear thresholds for each RV functional parameter where recovery was unlikely were identified. Chapter 9 is a pilot study where a standardised approach to right heart catheterisation is proposed for patients with suspected PHT-LHD. Taken together, the studies described in this thesis will contribute to our understanding of the demographic, imaging and haemodynamic characteristics of this highly prevalent, but under diagnosed and difficult to treat group of patients.