Hello, My Husband In The Past Couple Of Weeks (2

Hello, my husband in the past couple of weeks (2 to be exact) has been having issues with low heart rate and breathing. He is an athlete but not a professional, he's 37yrs old, no history of heart issues; specifically to his issues 2 weeks ago he had a black out, 33/100 heart rate and was taken to the ER. From that point it was discovered that his left carotid artery was 50% blocked; he was prescribed statin and an aspirin and both only increased his symptoms of dizziness etc. He doesn't take any illegal substances only a multivitamin pack which he has stopped since the incident. Since the incident he has episodes of dizziness, cloudiness, light-headiness, clammy hands, left side chest pain on the left pectoral area and feels as though he is forcing himself to breath at times b/c his heart rate has dropped so low. He's had numerous EKGs worn a halter monitor and the doc's still cant seem to exactly pin point it. My question is -is it safe to say that this is all related to his carotid arteries? Or could it be more then that?