METHODS: Electronic health records were linked to echocardiography data between 2015 and 2021 from patients in Tayside, Scotland (population~450 000). Incident HF diagnosis was classified into inpatient or outpatient and stratified by ejection fraction (EF). A non-HF comparator group with normal left ventricular function was also defined. The primary outcome was time to cardiovascular death or hHF within 12 months of diagnosis.

RESULTS: In total, 5223 individuals were identified, 4231 with HF (1115 heart failure with reduced ejection fraction (HFrEF), 666 heart failure with mildly reduced ejection fraction, 1402 heart failure with preserved ejection fraction and 1048 HF with unknown EF) and 992 with non-HF comparators. Of the 4231 HF patients, 2169 (51.3%) were diagnosed as inpatients. The primary outcome was observed in 1193 individuals with HF (28.1%) and 32 (3.2%) non-HF comparators and was significantly more likely to occur in individuals diagnosed as inpatients than outpatients (809 vs 384 events; adjusted HR: 1.62 (1.39-1.89), p<0.001), and this was consistent regardless of EF. For HFrEF patients first diagnosed as inpatients, those discharged on ≥2 GDMT had a reduced incidence of the primary outcome compared with those discharged on <2 GDMT (303 vs 175 events; adjusted HR: 0.72 (0.55-0.94), p=0.016).