Original Article

Severity classification of Fractional Area Change (FAC) in the left ventricle: A pilot study for evaluating systemic ventricular function by using FAC

• Naoko Ichikawa^1）,
• Yumi Shiina, MD, PhD^2）,
• Yasufumi Kijima^2）,
• Nobuyuki Komiyama^2）,
• Koichiro Niwa^2）

1. Clinical Laboratory, St. Luke’s International Hospital
2. Department of Cardiovascular Medicine, St. Luke’s International Hospital

doi: 10.34376/jsachd.O-2021-0005　PDF

早期公開日：2022年3月25日

Purpose: The disk summation method cannot assess systemic right ventricular function and single ventricular function because of its unique shape. Fractional area change (FAC) and eyeball ejection fraction (EF) methods are often used in such cases; however, the FAC cutoff value is vague. Estimation of left ventricular (LV) EF is classified into four stages; however, a severity classification system using the FAC method is lacking. This study aimed to assess LVFAC cutoff values based on systemic LVEF for evaluating systemic ventricle with complicated shape using FAC. We also evaluated the accuracy of the eyeball FAC method in the left ventricle because we are generally accustomed to evaluating eyeball right ventricle FAC, not LVFAC.
Methods: A total of 320 consecutive patients who underwent echocardiography were retrospectively enrolled. Eyeball LVFAC was estimated by well-trained sonographers. LVFAC was assessed simultaneously at the time of LVEF measurement.
Results: A total of 303 patients were classified as follows: 115 patients with normal contraction (LVEF>52%), 78 patients with mild dysfunction (40%<LVEF<51%), 62 patients with moderate dysfunction (30%<LVEF<40%), and 48 patients with severe dysfunction (LVEF<30%). The cutoff value of actual LVFAC measurements calculated from the receiver operating characteristic curve was 33% for mild dysfunction, 25% for moderate dysfunction, and 20.8% for severe dysfunction. The correlation between measured LVFAC and eyeball LVFAC was strong (r=0.94).
Conclusion: We classified LVFAC into four severity stages. LVFAC may be used as a simplified screening tool for any LV shape in local hospitals and emergency rooms, but further studies are needed.