My father has cardiomegaly with pulmonary congestion Yesterd

Patient: My father has cardiomegaly with pulmonary congestion. Yesterday, he was rushed to the hospital after having shortness of breath while driving. He has cough, and the doctors found out that the phlegm blocked the air way from his lungs that’s why he had a hard time breathing. He was discharged from the hospital 3 hours later, and they let him go home. My question is, was it risky? Is it possible to happen again even when he doesn’t have cough anymore? And what should be performed (as a first aid) in case it happened again? thank you.

Doctor: