WordNet (r) 3.0 (2006):

heart attack
    n 1: a sudden severe instance of abnormal heart function

Moby Thesaurus II by Grady Ward, 1.0:

71 Moby Thesaurus words for "heart attack":
   angina, angina pectoris, aortic insufficiency, aortic stenosis,
   apoplectic stroke, apoplexy, arrhythmia, arteriosclerosis,
   atherosclerosis, atrial fibrillation, auricular fibrillation,
   beriberi heart, cardiac arrest, cardiac insufficiency,
   cardiac shock, cardiac stenosis, cardiac thrombosis, carditis,
   congenital heart disease, cor biloculare, cor juvenum,
   cor triatriatum, coronary, coronary insufficiency,
   coronary thrombosis, diastolic hypertension, encased heart,
   endocarditis, extrasystole, fatty heart, fibroid heart,
   flask-shaped heart, frosted heart, hairy heart, heart block,
   heart condition, heart disease, heart failure, high blood pressure,
   hypertension, hypertensive heart disease, ischemic heart disease,
   mitral insufficiency, mitral stenosis, myocardial infarction,
   myocardial insufficiency, myocarditis, myovascular insufficiency,
   ox heart, palpitation, paralytic stroke, paroxysmal tachycardia,
   pericarditis, pile, premature beat, pseudoaortic insufficiency,
   pulmonary insufficiency, pulmonary stenosis,
   rheumatic heart disease, round heart, sclerosis, stony heart,
   stroke, tachycardia, thrombosis, tricuspid insufficiency,
   tricuspid stenosis, turtle heart, varicose veins, varix,
   ventricular fibrillation