8. Fatigue - Unusual fatigue is one of the main symptoms that indicates an impending heart attack. Women are more likely to report this type of symptom than men.7. Abdominal pain - Abdominal pains before a heart attack have an episodic nature, easing and then returning for short periods of time. Physical tension might worsen upset stomach pains. 6. Insomnia - Description: Symptoms include difficulty initiating sleep, difficulty maintaining sleep, and early-morning awakening.