Recently in heartwire an article summarizing data regarding blood pressure control in chronic kidney disease patients indicates higher mortality when treated to what are current recommended blood pressure goals. This is observational data and a more definitive trial titled SPRINT (Systolic Blood Pressure Intervention Trial) will not be concluded for another 5 years. The SPRINT trial is a treatment trial looking at this issue.
This is a second data set suggesting doctors and patients shouldn’t be firmly dogmatic in managing blood pressure. An earlier trial indicated that if we treat blood pressure levels to 120 systolic or lower in hypertensive patients we have lower rates of stroke but we observe an increase in the incidence of heart attacks (2 heart attacks for one less stroke). Blood pressure guidelines have recommended doctors and patient to be aggressive about blood pressure lowering in order to prevent kidney disease and other end organ damage from elevated blood pressure. These recommendations have been made based upon the clear understanding that high blood pressure is the number one reason for kidney disease.
Lowering blood pressure especially with certain blood pressure lowering classes of medications such as ace-inhibitors and angiotensin renin blockers help preserve kidney function. This latest study shows that meeting goals presently recommended were associated with higher mortality rates than if patients were allowed a more modest level of control. It is postulated that this is because average blood pressure matters for overall optimal blood circulation. Average blood pressure is known as mean arterial blood pressure. This number is calculated from using both the upper and lower blood pressure results. Often the lower blood pressure is low in persons with high upper (systolic) hypertension (high blood pressure). Dogma for treatment is to ignore that lower number. This data suggests perhaps it shouldn’t be ignored but rather incorporated into the individual patients profile for treatment goals. Calculating the Mean Arterial Blood Pressure will confirm that a person’s average blood pressure isn’t too low for normal tissue/organ function. Diastole counts twice as much as systole because 2/3 of the cardiac cycle is spent in diastole. An MAP of about 60 is necessary to perfuse coronary arteries, brain, kidneys. The normal/usual range is 70-110 mm/Hg.
In my practice I find following kidney function and the excretion of protein/albumin in the urine, along with combining more home blood pressure measurements allows me to confirm proper blood pressure control. I also perform 24 hour home blood pressure monitoring in selected patients to assure that I am not over or under treating my patients. I recommend all patients with a diagnosis of hypertension (high blood pressure) invest in a home blood pressure monitor and measure their blood pressures from time to time. I recommend these patients bring their recordings to their regular appointments as this lends better overall information about blood pressure control. If the doctor only has office numbers to decide on blood pressure control, they will often over medicate the patient. This is because office blood pressures are usually higher than numbers collected at home. We live at home but only visit the doctor. It stands to reason that your home measurements are more “real world” than the 15 minute office visit. 24 hour ambulatory monitoring well help “settle” any concerns if there is wide variance in the office data versus the patients recordings. It serves as the judge, if you will, in the event of conflicting information.