Heart attacks?

  What are the main causes of heart attacks ?  I thought the only way you could get one is from blocked arteries?   Can Cardoimyopathy cause one also ,if theEf% is too low?       Thanks for information and help.  Brenda

[CCF Cardio MD - MTR]

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Dear Brenda, thank you for your question.   A heart attack (myocardial infarction - MI) is caused by a blocked coronary artery.  This process usually occurs when an atherosclerotic plaque ruptures and a clot forms which occludes the vessel and prevents blood from supplying the heart muscle distal to the blockage.  If the blockage isn't relieved promptly (within 3-6 hrs), irreversible damage occurs to the heart muscle which may never recover function again.  Treatment strategies for MI are designed to rapidly restore coronary blood flow by dissolving the clot with thrombolytic medications or opening the artery with angioplasty.   If a large MI occurs and the blockage is not treated quickly enough, a portion of the heart muscle may die and the pumping function of the heart can be severely decreased thereafter.  When this happens, the condition is termed ischemic cardiomyopathy and the ejection fraction (a measure of left ventricular performance) is dramatically decreased.  Other causes of heart attacks are drugs like cocaine which constrict the coronary arteries when there may be no plaque at all.  Dilated cardiomyopathy is a condition where there is a primary dysfunction of the heart muscle with normal coronary arteries.  The heart muscle may be scarred from whatever condition caused the cardiomyopathy to occur, but a heart attack technically did not occur.  Perfusion imaging studies identify areas of scar in the heart muscle that indicated dead heart muscle.  These studies can show scar both in patients with ischemic and dilated cardiomyopathies, but only patients with ischemic cardiomyopathy will have had a heart attack from a blocked coronary artery that caused the scarring.  
I hope you find this information useful.  Information provided in the heart forum is for general purposes only.  Only your physician can provide specific diagnoses and therapies. Please feel free to write back with additional questions.
If you would like to make an appointment at the Cleveland Clinic Heart Center, please call 1-800-CCF-CARE or inquire online by using the Heart Center website at www.ccf.org/heartcenter.   The Heart Center website contains a directory of the cardiology staff that can be used to select the physician best suited to address your cardiac problem.