Usually, high blood pressure is because there is low cardiac and that condition is picked up by the endothelium cells of the vessel. The system responds as if there is blood loss from an injury, etc. The vessels constrict (to reseerve blood supply), heart rate increases, kidneys increase blood volume, etc.
Your high blood pressure is not the result of a physiological response to danger, but likely due to a renal disorder, etc. or an unknown causes. Essential hypertension indicates the cause is unknown, and be the fact the cause is unknown takes away a low heart rate to be the cause.
There can be two separate and unrelated conditions that could give a low heart rate and high blood pressure.