Just had heart cath. Doc said that there were areas that shows lack of oxygen in heart. What could that mean?

Blockage. You have blockages (stenoses) in your coronary arteries, the arteries that carry oxygen to your heart muscle. If your doctor didn't recommend intervention (surgery or balloon), they must be relatively mild. In that case, life style changes with improved diet, more exercise, aspirin, metoprolol, and a statin are indicated. (and, of course, no smoking, if you do/did that).