What connection: tachycardia dec2010, chest pain ever since, sudden illness jan11 followed by neuro symptoms, onset ms, chest pain most when fatigued?

Could be angina. Your symptoms of tachycardia may or may not be connected to the neurological condition. Thus, a prompt evaluation to look for blockages in the coronary arteries, or structural heart disease, such as problems with the valves or the heart muscle is warranted. Blood work is also important to check for anemia, thyroid, and renal(kidney) function.
Whew! Not enough information to form a connection. You may have heart issue separate from the neurological issue and need evaluation for both from cardiologist and neurologist. A good internist may find a connection (if there is one) as in lupus, lyme disease, medication side effects, heavy metal poisoning etc.