Why do some people still get heart attacks after being told to have a normal stress test ?

Atherosclerotic plaques are like “pimples” inside the lining of the arteries causing blockages and this process starts in ones body from teenage. Such “pimples” can grow over period of time and block the artery completely. A small pimple can also block the artery suddenly when it breaks open. The release of the pimple’s paste like contents causes the blood flowing through the artery to clot and block the flow completely. Properly conducted stress test can detect presence of blood flow limiting blockages (typically >70% narrowing) in the coronary arteries with an overall accuracy of approximately 90%. Hence a stress test cannot rule out minor blockages, which can potentially break open and cause heart attack. But the good news is that if a properly conducted stress test shows no evidence of tight blockages, the risk of heart attack in the succeeding year is less than 1%.

What are Stents ?

Most stents are metal scaffoldings inserted inside blood vessels, to keep it open after opening up the blockages. Over period of time, in some people new tissue material grows inside the stents resulting in re narrowing. Such re narrowing occurs less often with medicated stents.

Why is it important to take certain blood thinners after receiving stents ?

Lining of blood vessel (called endothelium) is usually smooth “like glass”, keeping blood flowing over it in its fluid form. When stents are inserted, there is injury to this lining. The blood flowing inside the metal stents and the injured lining has a tendency to clot formation. To prevent this, based on current scientific evidence, two blood thinners typically aspirin and plavix (clopidogrel) are prescribed for a certain period of time. During this time, it is expected that the stents are incorporated onto the blood vessel wall and the lining of blood vessels grows back. So it is absolutely essential that patients who receive stents should take these medications without defaulting even a day until your doctor recommends to stop it.

What is an arrhythmia (dysrhythmia) ?

Normally human heart beats like the ticking of a clock (at very regular intervals). Any irregularity in this is called an arrhythmia, also sometimes called dysrhythmia. Each normal beating of heart involves two cycles of activity. First is an electrical activity and the second is a mechanical activity. These cycles originate from the upper chambers (atria) and spread to the lower chambers (ventricles).

What is atrial fibrillation ?

Atrial fibrillation is a type of arrhythmia where the upper chambers of the heart give out electrical impulses rates at very fast rates. Many times, the lower chamber also beats at a faster rate as a consequence of high electrical impulses coming from upper chambers (though some of them gets stopped in the region between the upper and lower chambers).

Why do you have to take blood thinners for atrial fibrillation ?

When upper chambers give electrical activity at very fast rate, there won’t be enough time for effective mechanical pumping activity in the upper chambers. As a consequence, the blood flowing through the upper chambers can stagnate resulting in clot formation. Such clots can break off and go to different portions of the body including brain, causing strokes. In order to prevent or reduce this chance, blood thinners are often prescribed.