As noted by many others you are not close to requiring surgery. It seems that is when you go to 5 cm or over. I am also at 4.2 and found out at 4.0 cm 2-1/2 years ago. I also got very worried when I found out but after seeing heart specialists who have experience in treating the condition, I found out it is important to be checked at least annually to monitor the rate of increase, keeping heart rate low, blood pressure below 120 and no heavy lifting or strenuous activities. A lot of good information in this blog by many others.