Heart Failure with Mildly Reduced EF Has Been Consolidated, Not Abolished
The Canadian Cardiovascular Society/Canadian Heart Failure Society has consolidated HFmrEF (EF 41-49%) and HFpEF into a single unified term: heart failure with nonreduced ejection fraction (HFnrEF, LVEF >40%). 1 This represents a nomenclature change rather than elimination of the category—patients with EF 41-49% are still recognized and actively treated.
Why This Change Occurred
The 2025 CCS/CHFS guidelines made this consolidation because:
- Treatment approaches are now similar across the EF 41-49% and ≥50% spectrum, particularly with SGLT2 inhibitors showing consistent benefit across both groups 1
- The artificial distinction between HFmrEF and HFpEF created unnecessary complexity without meaningfully changing management
- EF values in this range fluctuate over time, making rigid categorization less clinically useful 2
Current Treatment Approach for EF 41-49%
First-line therapy (Class I recommendation):
- SGLT2 inhibitors (dapagliflozin 10 mg daily OR empagliflozin 10-25 mg daily) 1, 3
- These reduce heart failure hospitalizations across the entire >40% EF spectrum
- Start immediately—no titration needed
Second-line therapies (Class IIa-IIb):
- Sacubitril-valsartan (ARNI): Start 24/26 or 49/51 mg twice daily, target 97/103 mg twice daily 1, 3
- Mineralocorticoid receptor antagonists: Spironolactone 12.5-25 mg daily (target 25-50 mg) or finerenone 10-20 mg daily (target 20-40 mg) 1
- Evidence-based beta-blockers (carvedilol, metoprolol succinate, or bisoprolol) 3
- ARBs (candesartan 4-8 mg daily, target 32 mg daily) 1
Key Clinical Distinctions
The EF 41-49% range shares characteristics with both HFrEF and HFpEF:
- Etiology resembles HFrEF (high prevalence of ischemic heart disease) 4
- Prognosis and comorbidity profile closer to HFpEF 2
- Hospitalization rates intermediate between HFrEF and HFpEF 5
Treatment response: Patients on the lower end of this spectrum (EF 41-44%) respond similarly to HFrEF patients, supporting use of guideline-directed medical therapy 3
Important Caveats
- One-third of patients with EF 41-49% will transition to either HFrEF or HFpEF during follow-up 2—repeat LVEF assessment is essential
- The 2022 AHA/ACC/HFSA guidelines still use the term "HFmrEF" 3, while the 2025 Canadian guidelines use "HFnrEF" 1—both recognize and treat this population
- Device therapy (ICD/CRT) remains reserved for those with EF ≤35% or other specific indications 2
Bottom Line
Heart failure with EF 41-49% has not been abolished—it has been reclassified under the broader HFnrEF umbrella because treatment strategies now apply across the >40% EF spectrum. The most important change is that SGLT2 inhibitors are now first-line therapy with Class I evidence for this entire population.