What are some tips for visual estimation of ejection fraction when trying to difference between low-normal (50-55%) and mildly reduced (45-50%)?

Differentiating between a low-normal (50–55%) and a mildly reduced (45–50%) ejection fraction (EF) is inherently difficult with visual estimation alone because the difference is subtle. When evaluating point-of-care ultrasound, it is important to consider the limitations of the device you are using....