Cardiac valve surgery in Far North Queensland, Australia. A retrospective audit of rheumatic heart disease prevalence, patient demographics and surgical management
Authors: Sutcliffe S , Dobroskok V 
Published: January 2023

Abstract

Funding Acknowledgements
Type of funding sources: None.

Background
Rheumatic heart disease (RHD) is a preventable valve disease following acute rheumatic fever. It results in &gt;300,000 deaths annually worldwide (1). While commonly encountered in the developing world, the prevalence in Australia remains high with over 6000 patients currently living with RHD (2). This disease is over-represented in Northern Australia among the indigenous community with Aboriginal and Torres-strait Islander people accounting for over 80% of cases (2).

Purpose
This audit will evaluate the contribution of RHD to valve surgeries in Far North Queensland (FNQ) and the effect this has on procedure type and patient demographics.

Methods
We analysed a cohort of 200 consecutive patients from a regional centre in FNQ referred for valve surgery. We recorded age, gender, indigenous status, valve aetiology, ejection fraction (EF), surgery type, and procedure urgency. This data was then compared to the latest European Association for Cardio-Thoracic Surgery (EACTS) registry report (3).

Results
136 male and 64 female patients underwent 162 elective and 38 emergent valve procedures. The surgeries performed were bioprosthetic AVR (119), mechanical AVR (12), bioprosthetic MVR (14), mechanical MVR (11), TAVR (17), mitral valve repair (25), tricuspid valve repair (6) and balloon valvuloplasty (5) with combined CABG (33) and aortic root surgery (20). Average age at surgery was 64.2 years (range 21 – 89) which is significantly younger than the EACTS age at aortic, mitral and combined valve/CABG procedures. Notably, the average age at surgery reaches 75 years in European countries with a gross national income of $70,000 per capita. However, this is not evident in FNQ. 27 of the 200 procedures were for RHD and the average age of these patients was 45.4 years which explains this discrepancy. Indigenous patients accounted for 16.5% of total, and 77.8% of rheumatic valve surgeries. Mechanical prostheses comprised 15% and 48% of total and rheumatic valve replacements respectively which contrasts with 30-40% in the EACTS registry. RHD also accounted for almost the entirety of tricuspid valve surgeries and balloon valvuloplasties. The EACTS report suggested higher EF’s in Asian countries due to higher prevalence of RHD. This was not observed in our data with no statistically significant difference in EF between RHD patients and the overall cohort. Unfortunately, there is a lack of valve pathology data in the EACTS registry which limits further comparisons.

Conclusion
RHD is responsible for a significant proportion of valve surgery in FNQ. The indigenous population accounts for a vast majority of these patients. This has caused a shift towards lower age at surgery, higher proportions of mechanical valve replacements, valvuloplasties and tricuspid valve replacements. EF did not significantly differ in patients with rheumatic valve pathology. More data surrounding valve pathology is needed to draw similar conclusions in the EACTS cohorts.