The statement "I had a heart attack" is completely meaningless.
In general, this means there is some dead (necrotic) tissue, however the area of the "infarct", as well as the position, can vary greatly. Many people who have an infarct live long and productive lives.
"Pins and needles" in the left arm represent symptoms (potentially) of cardiac ischemia - that is to say the heart muscle may not be getting enough oxygen. Such a symptom should be reported promptly to a physician and warrants a trip by ambulance to an ER. This does not necessarily mean the problem is life-threatening.
It is commonly caused by a spasm of one of the two major blood vessels providing oxygen to the heart, and usually nitroglycerine is prescribed to open the vessel.
You need to have a long heart-to-heart talk with your cardiologist.
If you are experiencing angina, the use of nitroglycerine and immediate rest may be enough to ward off a serious, perhaps fatal outcome.
If these symtpoms occur again it warrants a call to 911.
I would certainly follow up with your doctor with these symptoms. Perhaps even go through the ER. Some symptoms you do not want to wait out. Take care, Ally