Hello,You have posed a very interesting question.Your doctor and cardiologist were right in reassuring you since you are young and no medical conditions you need not worry.
In the elderly therere is reason to keep the diastolic higher while controlling the systolic hypertension.Due to stiffening if the aorta and atherosclerosis,there risk perdictor, is the wide pulse pressure. ie increased systolic and lowered or normal diastolic.The diastolic mainly drives the coronary flow and the systolic,the predictive factor in stroke,congestive cardiac failure and increased left ventricular mass.
Thus in coronary heart disease and in elderly with systolic hypertension there is reason to reduce the systolic BP without compromising the diastolic.
Dr.M.Jagesh kamath MBBS. Dvd Consultant dermatologist