Blockage in hearts blood vessels is seen by angiography and the blockage is a measure of approximation which means having an exact 46% blockage is not practical ... It might be that what you are talking about is the hearts pumping function (ejection fraction) which is measured by echocardiography and can be measured exactly. Without a proper history it's difficult to answer your questions. But since he has a heart disease some things are important to follow.. Like..
Control your blood pressure/
sugar
Lower your cholesterol
Don't smoke
Get enough exercise
Take medication regularly and do not stop any medication without consulting your doctor
Check your health status with your doctor every 3-6months
Next Steps
Send detailed history and records for a more individualized advice