How high does blood pressure get before a heart attack?

It doesn't: Although high blood pressure is a risk factor for coronary heart disease, there is no evidence that there is an acute rise in blood pressure prior to a heart attack.

Not a direct cause: No number is the "magic number" but very high pressures (for example >200/>110) when associated with angina are considered a "hypertensive emergency" and should be promptly treated. Symptoms of stroke, heart failure, kidney failure, or encephalopathy (confusion) are the key symptoms of a hypertensive crisis.

Varies: High blood pressure over years damages blood vessels leading to things like stroke & heart attack. BP > 140/90 over time increases the risk for these problems. The longer the time and the higher the blood pressure, the > risk. No hard and fast cut off. If the blood pressure goes up quickly to very high levels (> 180/110 or so) can cause problems like heat failure, stroke more suddenly, .