High blood pressure is a symptom, not a disease itself, though it can be a sign of various diseases, as well as being a result of stress, maybe just caused by having your blood pressure taken (known as 'white coat syndrome'. So the medical would be signalled for the abnormal bp, and referred to the MAs, who would want to know what was the cause of it in your particular case.
The MAs will not declare that you have ASH (acceptable standard of health) until they've got a report from a doctor or specialist, either saying the high reading was temporary, and showing another test within the normal range, or saying that you turn out to have (whatever) condition, it is now being treated, and the treatment is expected to keep the bp under control in the future. And the CO can't issue a visa without being told by the MA that you have ASH.
Apart from that, for your own sake, you need to get checked out thoroughly by your own doctor, because you need treatment if this turns out to be caused by a disease - the body can't continue to function properly for long in that state.
You don't have to submit the medical WITH the EOI. If your EOI is selected, you are sent an ITA to fill in and return with all kinds of evidence, including the medical, and you have three months to do it. You could see your doctor now, and start any treatment recommended. There could be a big difference before you have to submit the medical.
Otherwise, if you meant that you are about ready to submit the ITA, you could send in this existing medical, knowing it will be referred to the MAs, and then send in a report from your doctor about treatment and prognosis, hoping for it to catch up with the medical before it gets its turn with an MA, and that it will pre-empt whatever questions the MA would otherwise have asked. (The point of this is to cut down the time that would be spent with the MA sending requirements for reports, and you having to go and get them done, then another wait while the doctor's letter got seen, etc., etc..)
Take care of yourself.