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Cardiac stress test - Wiki

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        12:35 PM, March 23, 2006
      
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        Look at "Further Research" section at bottom of Wiki article.  Excellent and state of the 
        art.
      
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        Stress testing methods, though more effective than a resting EKG, only detect medium to 
        high grade flow limitations; this assuming the testing is fully and aggressively 
        performed. However, most acute artery flow disrupting events leading to heart attacks are 
        due to rupture of "vulnerable plaques". Most of the "vulnerable plaques" cause less than 
        40% 
      
      
        <u>lumen </wiki/Lumen></u>
      
      
         narrowing, a degree of 
      
      
        <u>stenosis </wiki/Stenosis></u>
      
      
         too small for most stress testing methods to detect
      
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        Historically, through the mid-1980s, it was believed that detecting these high grade 
        stenoses was the key to recognizing people who would have 
      
      
        <u>heart attacks </wiki/Myocardial_infarction></u>
      
      
         in the future. However, there was also long-standing experience that some people could 
        exercise all the way to maximum predicted heart rate, have no abnormal symptoms and 
        completely normal stress test results, only to die of a massive 
      
      
        <u>heart attack </wiki/Myocardial_infarction></u>
      
      
         within a few days to weeks. From the 1960s to 1990s, despite the success of stress 
        testing identifying many who were at high risk for 
      
      
        <u>heart attack </wiki/Myocardial_infarction></u>
      
      
        , its failure to correctly identify many others was a conundrum, discussed in medical 
        circles but 
      
      
        <i>unexplained</i>
      
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        By the early to mid-1990s, it became more widely recognized that rupture of more rapidly 
        evolving and unstable 
      
      
        <u>atheroma </wiki/Atheroma></u>
      
      
        , 
      
      
        <i>hidden</i>
      
      
         within the walls of the coronary arteries, called "vulnerable plaques", even though they 
        often produce little or no 
      
      
        <u>stenosis </wiki/Stenosis></u>
      
      
         of the coronary lumen, is the primary event which produces most 
      
      
        <u>heart attacks </wiki/Myocardial_infarction></u>
      
      
        
      
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        Two clinical trials published in the late 1990's, focusing on the relation between plaque 
        structure, lumen stenosis and 
      
      
        <u>myocardial infarction </wiki/Myocardial_infarction></u>
      
      
        , in which each individuals coronary anatomy was tracked with both 
      
      
        <u>angiography </wiki/Angiography></u>
      
      
         and 
      
      
        <u>IVUS </wiki/IVUS></u>
      
      
         found that 75% or greater stenotic areas were responsible for only about 14% of heart 
        attacks. The typical heart attack occurred at an artery location with extensive, eccentric 
        plaque within the wall but a luminal stenosis of only 20%. This finding added further 
        evidence to the importance of the concept of vulnerable plaques. The detection of these 
        vulnerable plaques using high resolution CT, MRI, IVUS, OCT (Optical Coherence 
        Tomography), and molecular imaging is currently hotly researched. For CT, as of 2005, 
        64-slice multidetector machines are providing the best artery and lumen images, yet still 
        do not clearly reveal which plaques are vulnerable. 
      
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        Unfortunately, cardiac stress tests are only capable of detecting medium to high grade 
        limitations of blood flow to the left ventricular heart muscle which may produce recurring 
      
      
        <u>angina </wiki/Angina></u>
      
      
        , not the 
      
      
        <u>atheroma </wiki/Atheroma></u>
      
      
         which produce 
      
      
        <u>heart attacks </wiki/Myocardial_infarction></u>
      
      
        . 
      
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        <i></i>
      
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