Comparison between pre-hospital and in-hospital ST-Elevation Myocardial Infarction (STEMI) from 2003 to 2016 in New South Wales, Australia: a population-linkage data analysis

Background

Outcomes among patients presenting to hospital with STEMI (PH-STEMI) are favourably impacted by access to reperfusion, which has improved in Australia in recent years. Reperfusion rates and outcomes among patients with in-hospital STEMI (IH-STEMI) in Australia are not well described.

Purpose

We compared frequency of percutaneous coronary intervention (PCI) and all-cause mortality trends between patients with PH-STEMI and IH-STEMI over 13-years in a statewide cohort.

Methods

Patients diagnosed with STEMI (both PH and IH) were identified from the NSW Admitted-Patient-Data-Collection registry from 2003 to 2016 and linked to the death registry until 31-December-2018. We calculated the proportion with PCI over time, and rate of long-term mortality was determined with adjustment for age, sex, year of presentation and PCI.

Results

66,794 STEMI patients were identified; 57,721 (86%) had PH-STEMI. Patients with IH-STEMI were older (mean±SD: 75±13 vs 66±14 years), and more likely to be female (46.2% vs 29.8%) than PH-STEMIs. Patients with IH-STEMI were less likely to undergo PCI (17.1% vs 55.8%). From 2003-4 to 2015-6, overall rate of PCI increased for STEMI, but remained lower for IH-STEMI compared to PH-STEMI (9.5% to 23.9% vs 40.4% to 65.5% respectively).

All-cause mortality from STEMI fell over time in both groups. Predictors of mortality improvement in the PH and IH-STEMI populations respectively included PCI: (adjusted hazard ratio [aHR]=0.48, 95% confidence interval [CI]: 0.46–0.49 and (aHR=0.48 [95% CI: 0.44–0.53) and year of event: (aHR=0.74 [95% CI: 0.69–0.8] and aHR=0.79 [95% CI: 0.70–0.88]). Adding the interaction term PCI by year group to the mortality models showed that this progressive reduction in mortality by year grouping was accounted for by the performance of PCI in the PH-STEMI group (p<0.0001) but not in the IH-STEMI group (p=0.65).

Conclusion

A fall in mortality in patients with PH-STEMI in NSW was observed from 2003 to 2016 and was accounted for by increasing use of PCI. A more modest fall in mortality was seen in patients with IH-STEMI and this was independent of PCI which was under utilised in this population. Efforts to further improve outcomes in STEMI should include a greater focus on patients with in-hospital events.

Funding Acknowledgement

Type of funding sources: None.

P5 Clinical utility of stress echocardiography in remote indigenous and non-indigenous populations: a 10-year study in central Australia

Background

Central Australia is a vast, geographical region spanning some 830,000 square kilometres. It is the most populous Indigenous region in Australia (44%) and a great distance from tertiary centres (1,500km). Non-invasive testing is important in this setting due to the high prevalence of cardiovascular disease and long-distance travel required for coronary angiography, the latter with significant logistical, financial, and cultural barriers. Although stress echocardiography has been extensively validated as a long-term prognostic tool in selected populations, we are not aware of prior studies in remote Indigenous and non-Indigenous individuals.

Purpose

To determine whether stress echocardiography can adequately risk stratify and quantify the long-term prognosis of Indigenous and non-Indigenous individuals in remote Central Australia.

Methods

Consecutive individuals undergoing stress echocardiography in Central Australia between 2007 and 2017 were included. Exercise or dobutamine stress echocardiography was performed and reported via standard protocols.  Individuals were followed up for the primary outcome of all-cause mortality.

Results

One thousand and eight patients (54% Indigenous, 63% dobutamine stress) were included. Indigenous patients were younger, more likely to be female, and had a greater prevalence of cardiometabolic comorbidities (p < 0.05 for all). Overall, 797 (79%) patients had no abnormality during rest or stress echocardiography, with no difference according to ethnicity (p > 0.05).  After a mean follow up of 3.5 ± 2.4 years, 54 (5%) of patients were deceased; 127 (14%) patients underwent revascularization and were censored from follow-up. In patients with a normal test, annual mortality averaged 1.3% over 5 years of follow up, with annual mortality being significantly higher in Indigenous compared to non-Indigenous individuals (2.0% vs 0.6% respectively). Individuals with either ischemia or scar had a significantly worse long-term outcome compared to those with a normal test (Figure). In multivariate analyses, increasing age (HR 1.04 [95% CI 1.01-1.08]), chronic kidney disease (HR 4.83 [1.79-13.02]), and lack of ACEI/ARB use (HR 0.19 [95% CI 0.09-0.42]) were associated with all-cause mortality. Although Indigenous ethnicity was a univariate predictor of mortality, this association was attenuated and non-significant in multivariate analyses.

Conclusion

Indigenous patients in remote Central Australia with a normal stress echocardiogram had a significantly higher annual rate of mortality compared to their non-Indigenous counterparts. However, this association may be in large part due to comorbid conditions. A normal test in Indigenous individuals was still able to adequately risk-stratify and identify a lower risk group of patients in whom ongoing local medical management and focusing on cardiometabolic risk factor reduction is likely to be appropriate.

Abstract P5 Figure. Kaplan Meier survival curve