Abstract

Background: Heart failure with reduced ejection fraction (HFrEF), defined as a left ventricular ejection fraction (LVEF) of <40%, after acute coronary syndrome (ACS) is associated with increased mortality rates. However, the long-term prognostic impact of HF in patients with mildly reduced EF (HFmrEF), defined as a LVEF of 40–49%, who undergo primary percutaneous coronary intervention (PCI) remains unclear. Hypothesis: Patients with HFmrEF have a better prognosis than those with HFrEF and a worse prognosis than patients with HF with preserved EF (HFpEF), defined as a LVEF of ≥ 50%. Aims: We compared the long-term prognosis among HFpEF, HFmrEF, and HFrEF patients. Methods: A total of 836 consecutive ACS patients who underwent emergency PCI at our hospital between April 2014 and March 2024 were retrospectively recruited. We compared all-cause mortality and adverse cardiovascular events, including cardiac death and heart failure hospitalization. Patients were divided into three groups based on LVEF assessed by echocardiography within 1 month after PCI: HFpEF, HFmrEF, and HFrEF. Results: After excluding 117 patients who lacked echocardiographic data, 719 patients were included (HFpEF, 443; HFmrEF, 180; HFrEF, 96). Patients with lower EF were older and had higher plasma brain natriuretic peptide levels at admission. During a median follow-up period of 3.8 years (interquartile range: 1.5–6.3), 105 patients (13%) died. Patients with lower EF had a higher incidence of all-cause mortality and adverse cardiovascular events ( Figure ). Multivariate analysis indicated no difference in all-cause mortality between HFrEF and HFmrEF groups (adjusted hazard ratio (HR) 1.07, 95% confidence interval (CI) 0.44–2.60), although adverse cardiovascular events were significantly different (adjusted HR 0.44, 95% CI 0.24–0.82). On the other hand, there was no difference in all-cause mortality between HFmrEF and HFpEF groups (adjusted HR 0.49, 95% CI 0.31–0.79), although adverse cardiovascular events were significantly different (adjusted HR 0.35, 95% CI 0.18–0.69). Conclusion: In patients with ACS following emergency PCI, HFmrEF is associated with a better prognosis compared with HFrEF, but with a worse prognosis than HFpEF.