My brother is 27 years old and had an echo due to family history of HCM on my father s side. However, my father (56 years old), myself (29) and my brother have all had echo and ecg recently without any sign of HCM. My brother had a yearly follow up echo and his IVSd a year ago was 0.9cm, and this year 0.78cm. His ejection fraction last year was 60% and this year 76%. Doctor said everything is normal and his heart function is very good without sign of HCM. However, his high ejection fraction this year worries me ? I read that high EF could be a sign of HCM, but his septal thickness was normal. What could cause this increase then ?