Footslogger:
It's good to hear that you are doing okay. As a cardiologist and technical diving instructor, while limiting your depths is reasonable that is not really the main issue in diving after a heart attack. The main issue is the potential workloads involved. It is recommended that patients after a heart attack be able to exercise to 13 mets (about 12 minutes on a standard treadmill) before returning to diving and that they have normal heart muscle function (left ventricular ejection fraction above 50%). Additionally, they should have no evidence of a limitation to blood flow to their heart on stress testing.
The reason for these recommendations is that even the warmest, calmest, shallow Carribbean dive can turn into a lot of work if the seas pick up, currents develop, the diver surfaces a long way from the boat and has to make a long surface swim, or if he or she has to assist a buddy in trouble. All of these things are unpredictable and put both the diver and their buddy in jeopardy.
Another issue is the risk of dangerous heart rhythms with loss of consciousness after a heart attack. These are most often associated with weakened heart muscles or ischemia (limited blood flow to the heart). While a loss of consciousness topside can be dangerous and life-threatening, loss of consciousness under water is usually fatal.
It is not my intent to scare you or tell you not to dive. I just think you should understand the risks you are taking. Also, does your cardiologist know anything about diving? Most do not.
Life is all about weighing the risks and benefits of activities. If you and your (informed) cardiologist feel the risk of diving to you is low and your enjoyment from it is high, then if you and your buddy are willing to accept the risks, I would say return to diving.
Just my 2 cents.
Doug