I cannot provide information from 2026 ESC guidelines as they do not exist in the evidence provided.
The evidence you've supplied consists primarily of 2022 AHA/ACC/HFSA guidelines 1, 2, 3, older ESC guidelines from 2008 4 and 2016 5, and various research papers. There are no 2026 ESC guidelines available in this evidence set.
However, I can answer your question using the most recent and authoritative guidelines available in the evidence provided.
Heart Failure Classification by LVEF (Based on 2022 AHA/ACC/HFSA Guidelines)
According to the most recent guidelines available, heart failure categories are defined as follows:
LVEF-Based Categories 1:
- HFrEF (HF with reduced EF): LVEF ≤40%
- HFmrEF (HF with mildly reduced EF): LVEF 41-49%
- HFpEF (HF with preserved EF): LVEF ≥50%
- HFimpEF (HF with improved EF): Previous LVEF ≤40% with follow-up measurement >40%
Diagnostic Criteria for HFmrEF and HFpEF
Both HFmrEF and HFpEF require three essential components for diagnosis 1:
1. Clinical Syndrome of Heart Failure
- Presence of current or prior symptoms and/or signs of HF
2. Appropriate LVEF Range
- HFmrEF: LVEF 41-49%
- HFpEF: LVEF ≥50%
3. Evidence of Increased LV Filling Pressures (at rest, exercise, or provocation) 1
This can be demonstrated by any of the following:
Natriuretic Peptide Elevation:
- Elevated BNP or NT-proBNP levels
Echocardiographic Evidence:
- E/e' ≥15 (definitive evidence of elevated filling pressures)
- E/e' 8-15 (intermediate, may require further evaluation)
- Other diastolic dysfunction parameters
Invasive Hemodynamic Measurements:
- Elevated pulmonary capillary wedge pressure
- Elevated LV end-diastolic pressure
- Abnormal PA pressures at rest or with exercise
4. Supportive Structural Heart Disease Evidence 1
While not absolutely required, structural abnormalities strengthen the diagnosis:
- Increased left atrial size/volume (left atrial volume index)
- Increased LV mass (LV mass index)
- LV wall thickness abnormalities
Diagnostic Algorithm When Uncertainty Exists
If the diagnosis remains uncertain after initial evaluation 1:
Exercise Stress Testing with Echocardiography
- Assess diastolic parameters during exercise
- Look for provokable elevation in filling pressures
Invasive Hemodynamic Assessment
- Right heart catheterization at rest or with exercise
- Measure pulmonary capillary wedge pressure, PA pressures, stroke volume, cardiac output
H₂FPEF Score for HFpEF 1
A clinical composite score (0-9 points) integrating:
- Obesity
- Atrial fibrillation
- Age >60 years
- Treatment with ≥2 antihypertensive medications
- E/e' ratio >9
- PA systolic pressure >35 mmHg
Interpretation:
- Score <2: Low likelihood of HFpEF
- Score 2-5: Intermediate (requires further hemodynamic evaluation)
- Score ≥6: High likelihood of HFpEF
Critical Clinical Pitfalls
The key distinction from HFrEF: Unlike HFrEF where LVEF alone is sufficient for diagnosis, HFmrEF and HFpEF require objective evidence of elevated filling pressures beyond just symptoms and LVEF 1. Simply having dyspnea and LVEF ≥41% is insufficient—you must document the cardiac dysfunction causing the symptoms.
LVEF trajectory matters: A single LVEF measurement may be inadequate for HFmrEF patients, as they often represent a dynamic state—either improving from HFrEF or deteriorating toward it 1, 2.
If you need information specifically from 2026 ESC guidelines, please provide that evidence source.