A Review of Coronary Artery Bypass Grafting in the Indigenous Australian Population

Outcomes of Indigenous Australians undergoing isolated coronary artery bypass graft surgery at a single institution

INTRODUCTION

The 'gap' continues to exist between the Indigenous and non-Indigenous populations within Australia, with Indigenous Australians continuing to experience poorer health outcomes, and a reduced life expectancy of 10.6 years for males and 9.5 for females. Indigenous Australians are far more likely to suffer from ischaemic heart disease. We sought to investigate the outcomes of Indigenous Australians undergoing isolated coronary artery bypass graft surgery (CABG) at a single institution.

METHODS

A retrospective cohort study comparing Indigenous with non-Indigenous Australians from prospectively collected data were performed for all patients who underwent isolated CABG at a single centre between 2015 and 2018. The primary endpoint was 30-day mortality with secondary endpoints including deep sternal wound infection, new renal failure, length of stay, stroke and rate of readmission.

RESULTS

A total of 905 patients were included in the study. The Indigenous cohort had 130 patients and the non-Indigenous cohort contained 775 patients. The baseline preoperative characteristics were significantly different between the two cohorts, with Indigenous patients younger (55.7 vs. 64.6 years), more likely to be female (33.1% vs. 16.4%) and to be dialysis-dependent (10% vs. 1.2%). The primary outcome was more likely in Indigenous Australians, with a 30-day mortality rate of 3.1% compared with 0.8%. There was a higher incidence of new renal failure (12.3% vs. 5.9%), red blood cell transfusion (30% vs. 20.8%).

CONCLUSION

Indigenous patients undergoing CABG at our institution have significantly more co-morbidities as well as worse post-operative outcomes and strategies to address this are urgently required.

Heart failure among Indigenous and non-Indigenous Australians in remote Central Australia

BACKGROUND

There is a paucity of data on the burden of heart failure (HF) in Central Australia, the most populous Indigenous region in the country.

AIMS

To characterize Indigenous and non-Indigenous Australians with HF in Central Australia.

METHODS

Consecutive patients with HF and reduced ejection fraction <50% were included for the period 2019 to 2021. Clinical, echocardiographic and major adverse cardiovascular events (MACE) data were collected.

RESULTS

Four hundred twenty-four patients with HF were included (70% Indigenous, 59% male; follow-up 2.2 ± 0.5 years). Indigenous Australians were younger (53 ± 15 vs 68 ± 13 years, P < 0.001) with higher rates of rheumatic heart disease (18% vs 1%, P < 0.001), diabetes (63% vs 33%, P < 0.001) and severe chronic kidney disease (CKD; 32% vs 7%, P < 0.001). HF was more prevalent among Indigenous (138 [95% confidence interval (CI), 123-155] per 10 000) compared with non-Indigenous Australians (53 [95% CI, 44-63] per 10 000), particularly among younger individuals and females. There were similar HF aetiologies between groups. Guideline-directed medical therapy (GDMT) was suboptimal and similar between the groups: angiotensin-converting enzyme inhibitor/angiotensin receptor blocker (64% vs 67%, P = 0.47) and β-blockers (68% vs 71%, P = 0.47). Indigenous Australians had a significantly higher rate of MACE (54% vs 28%, P < 0.001) and death from any cause (24% vs 13%, P = 0.013).

CONCLUSIONS

HF is more than two times as prevalent among Indigenous Central Australians, particularly among younger individuals and females. Despite similar HF aetiologies and GDMT, MACE and mortality outcomes are higher in Indigenous individuals with HF. These data have implications for efforts to close the Indigenous gap in morbidity and mortality.

Quantification of the internal mammary artery size in Aboriginal and Torres Strait islanders

BACKGROUND

Variation in size of the internal mammary artery has been demonstrated in ethnic groups, but not reported in Aboriginal patients. We hypothesised that the left internal mammary artery is smaller in Aboriginal patients compared to non-Aboriginal patients and aimed to determine the impact on survival following coronary artery bypass graft (CABG) surgery.

METHODS

Left internal mammary artery size was compared between Aboriginal (n = 345) and non-Aboriginal (n = 1819) in 2343 patients undergoing CABG at Flinders Medical Centre from January 2010 to June 2021. To determine the association with-survival we used Kaplan-Meier survival analysis and Cox proportional hazard models adjusted for preoperative variables.

RESULTS

There was a significant difference in left internal mammary artery (LIMA) size-Aboriginal 1.8 ± 0.4 mm; non-Aboriginal 2.1 ± 0.4 mm (P < 0.001)-and left anterior descending (LAD) artery size-Aboriginal 1.7 ± 0.3 mm; non-Aboriginal 1.9 ± 0.3 mm (P < 0.001). Aboriginal patients were more likely to have the LIMA discarded (9.3% vs. 0.4%) and to receive a LAD vein graft (17% versus 3%) (P < 0.001). There was no difference in 30-day mortality or survival <5 years.

CONCLUSION

This study supports the hypothesis that the left internal mammary artery is smaller in Aboriginal patients compared to non-Aboriginal patients. Although Aboriginal patients were more likely to receive a venous conduit to the LAD, we observed no difference in survival up to 5 years. This data contrasts with reported outcomes of other ethnic groups.