There are no absolute signs of impending heart attack in women or men for that matter. Signs and symptoms of an MI ( myocardial infarction) vary from person to person, however the 1st things that would raise my suspicion of possible MI in a woman would be, over age 40, nausea and possibly vomiting, dyspnea, diaphoresis, followed by chest pain with possible radiation to jaw, upper back and left arm.
Allways cause for suspicion and the need for a 12 lead EKG. Women are less likely to have an MI, but more likely to die from one because the symptoms are easier to to ignore or pass off as indigestion, gas, ect.
Asystole is the best sign of impending death, although if it is a witnessed arrest, with quick CPR your outcome is much more favorable
Inferior MI's seem to be the most troublesome, followed by anterior MI's