Introduction The newly-defined group of heart failure with mid-range ejection fraction (mrEF) is increasingly established as a distinct entity among chronic heart failure patients. In the acute setting, nonetheless, there is lack of well-defined pathways to manage patients with mrEF following ST-segment elevation myocardial infarction (STEMI). Whether the mrEF group has different demographic features and/or altered prognosis from other EF categories are yet to be determined. We sought to investigate the long-term cardiovascular outcomes of mrEF post STEMI and to identify if there were any clinical features that may help identify those who are at increased risk.
Methods Consecutive patients undergoing primary PCI from a large volume single centre were enrolled. Reduced EF (<40%), mrEF (40- 50%) and preserved EF (>50%) were defined using the European Society of Cardiology recommended cut-offs. Primary endpoint was defined as composite of death, re-admission with heart failure, sustained ventricular arrhythmia or implantable cardioverter defibrillator (ICD) over three years follow-up.
Results 552 patients were included in this study. Mean age was 63 ±13 years and 75% were male. The median EF was 50% (40- 55). 21% of patients were classified as reduced EF, 41% as mrEF, and 38% with preserved EF. There were significant differences across three subgroups (reduced EF, mrEF, and preserved EF respectively) in age (66 ±13, 62 ±13, 62 ±12, P= 0.017), troponin value [4606 (1589- 10000), 2819 (1059- 6347), 902 (329- 2869), (P<0.001)] and proportion of patients with normal renal function (69%, 82%, 88%, P<0.001) and anterior STEMI (70%, 45%, 20%, P<0.001).
There was a stepwise increase in the primary endpoint according to the EF category 6.2%, 18.5%, 34.8% P<0.001 (figure 1); hazard ratio (HR) for mrEF versus preserved EF 3.25 (95% CI 1.74 to 6.05), P<0.001, and HR for mrEF versus reduced EF 0.48 (95% CI 0.31 to 0.74, P= 0.001. The difference was derived from each of the primary components i.e. death (3.3%, 10.1%, 17.4%, P<0.001), re-admission with heart failure (2.9%, 6.2%, 13%, P= 0.002), and ventricular arrhythmia/ICD implantation (0%, 4.8%, 12.2%, P<0.001).
There were differential independent predictors of primary endpoint between mrEF and preserved EF (table 1&2). Normal kidney function was associated with better clinical outcomes in both EF categories.
Conclusion Patients presenting with STEMI and mrEF carried an intermediate risk over long term follow up. Further studies are required to assess if their risk is modifiable but importantly the mrEF group should not be considered as low risk patients
Conflict of Interest None
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