During a heart attack, does your blood pressure go up or down?
Blood pressure can go up or down, or remain normal during a cardiac event, so this is not helpful in making a diagnosis.
If a heart attack is suspected, low blood pressure could represent a serious problem because the heart is too weak to adequately maintain the pressure. The pressure may rise due to a large release of hormones that help deal with emergency situations (such as adrenaline) and likewise, could raise the pulse, cause sweating and other symptoms. And then again, the pressure may not be affected at all.
I hope this has been helpful. Here are some articles you might find of interest:
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Five Easy Ways to Help Your Heart