Wannabe With Irregular Heartbeat

Last month I went to a local doctor and had a DOT Physical for my Class D CDL (only issued by a handful of states). I passed the physical and the computerized test at the highway patrol and was issued the license. I told the doctor that I became aware that I had an irregular heartbeat about 15 years ago and had seen two physicians who said that my heart was healthy and it should not be a problem. The doctor listened again and said that he could not hear it. My wife listened a couple of nights ago and immediately heard the irregular beat. I have since decided that I want to get Class A license and plan on attending a commercial truck driving school relatively close to my home. Since I don't qualify for financial aid for this particular program, I will have to pay my tuition myself. The school told me that I can attend with my current medical card since it is recent. I fear getting my Class A CDL and failing a physical for a particular company. Should I get referred to a cardiologist and have them to document that this should not cause an issue beforehand? How is irregular heartbeat issues handled with these companies?