Preserved EF does not guarantee forward flow
71-year-old male, total hip arthroplasty. LVEF 58% — within normal range — but LVOT VTI 13 cm and CO 2.8 L/min indicate reduced forward output.
Clinical scenario
71-year-old male, scheduled for total hip arthroplasty following femoral neck fracture. History of hypertension and mild type 2 diabetes. Mild exertional dyspnea on stairs, otherwise independent. Preoperative TTE obtained.
Key TTE findings
LVEF 58% (preserved), LVOT VTI 13 cm (reference ≥ 18 cm), CO 2.8 L/min (reference ≥ 4.0 L/min), E/e' 12 (borderline), TAPSE 2.0 cm (normal).
How the tool reads this
LV systolic reserve: Possible (LVOT VTI < 16 cm and CO < 3.5). Filling pressure: Not fully evaluated (E/e' alone). Right heart: Normal.
Why preserved EF does not mean forward flow is adequate
LVEF reflects the fraction of blood ejected per beat — not forward output itself. If both the numerator (stroke volume) and denominator (end-diastolic volume) are small, EF can sit in the normal range even when cardiac output is reduced. A small LV cavity, tachycardia, or elevated afterload are common causes. In this case, LVEF is 58%, but LVOT VTI is only 13 cm — well below the reference range — indicating a low stroke volume. CO of 2.8 L/min reinforces that forward delivery to the tissues is reduced.
Seeing a 'preserved EF' report and stopping there risks missing this pattern. Checking LVOT VTI and CO alongside LVEF provides a more complete picture of true forward output.
Teaching points
- LVEF is an ejection fraction, not a measure of forward output — CO and stroke volume are separate assessments
- LVOT VTI < 18 cm is a meaningful signal of reduced forward flow even with a normal EF
- Make it a habit: when the report says 'preserved EF,' also check CO or LVOT VTI
What to watch in the OR
- Induction-related vasodilation can precipitate significant hypotension in patients with low forward output
- Rapid increases in volatile agent concentration or high spinal anesthesia can cause abrupt preload and afterload changes
- Consider early arterial line placement and have vasopressors drawn and ready at induction