Observational analysis of non-ST-segment elevation myocardial infarction invasive management and mortality over the decades.

Background: Routine invasive management by coronary angiography and revascularisation as appropriate reduces recurrent ischaemic events in non-ST-segment myocardial infarction (NSTEMI), but its mortality benefit is uncertain.

Methods: Within this state-wide retrospective cohort study, patients with a primary diagnosis of NSTEMI were identified from the New South Wales (NSW) Admitted Patient Data Collection database between 2003 and 2020 and linked to the NSW death registry. Primary outcomes were cardiovascular (CV) and all-cause mortality among NSTEMI patients stratified by in-hospital invasive management.

Results: Among 121 089 patients with NSTEMI (median age 71.4 years; 62.7% men), invasive management increased from 48.8% to 66.8% while all-cause in-hospital mortality decreased from 4.8% to 2.9% between triennial periods of 2003-2005 and 2018-2020, respectively. During the follow-up period (median 8.47 years), 47 304 (39.1%) patients died. CV mortality fell between 2003 and 2020 for those who were and were not invasively managed with greater magnitude in the former (subdistribution HR (sHR)=0.32, 95% CI 0.29 to 0.36; sHR=0.58, 95% CI 0.54 to 0.63, respectively, p_interaction<0.001). For all-cause mortality, the fall was significant for the invasively managed patients, with no plateau evident, but not in patients managed conservatively (adjusted HR (aHR)=0.56, 95% CI 0.52 to 0.61; aHR=1.00, 95% CI 0.95 to 1.06, respectively, p_interaction<0.001).

Conclusions: In patients presenting to NSW hospitals with NSTEMI between 2003 and 2020, we observed improvements in CV mortality in both invasively and conservatively managed patients while all-cause mortality improved in invasively but not conservatively managed patients. Wider implementation of routine invasive management may further improve long-term mortality among NSTEMI patients in NSW.