New blood pressure guidelines
Two days ago the American Heart Association and American College of Cardiology (AHA/ACC) released new guidelines for high blood pressure. Many news agencies covered this story and several of you have reached out for my opinion.
The most important change is the lowering of blood pressure goals in some patients to 130/80. To determine if you are one of those affected you must start by determining your 10-year risk of having a cardiovascular event. There calculators are available on-line, here is one from the AHA/ACC.
If your 10-year risk of a heart attack or stroke is <10%, your blood pressure should not exceed 140/90. If your 10-year risk of a heart attack or stroke is >10%, your blood pressure should not exceed 130/80.
However, when using a 10-year risk calculator everyone over the age of 65 has a >10% risk. This would recategorize a huge proportion of the population (tens of millions) as “hypertensive” requiring treatment.
Guidelines are created by a committee of experts that review evidence. This process has been criticized because there is often conflict of interest. Up to
on these panels have ties to industry. On the other hand, when it comes to high blood pressure almost all drugs are now generic and inexpensive so one could argue industry does not have much to gain at this point.
Why the sudden turn in recommendations? It all comes down to a new trial, the Sprint trial from 2015. This was a very large NIH funded trial in 9000 high risk subjects that showed dramatic prevention of strokes and heart attacks when systolic blood pressure was targeted to 120 compared with 140. However, there exists 3 decades of trials prior to Sprint that demonstrated different results. Most showed that there are tremendous benefits to bringing blood pressure from very high numbers (>200) to moderate numbers (160-180) but as one approaches 120 there are diminished returns and more side effects from the multiple medications required. For instance, If blood pressure is brought to 120/80 with medication at times it may dip as low as 100/60. If you are 75 years old with poor balance, an episode of lightheadedness from low blood pressure may cause a fall and fracture.
So what evidence should prevail? The single recent well done trail or the pile of trials that preceded it? It’s hard to say. I am personally uncomfortable putting all my eggs in one basket. A trial of this importance that conflicts with the results of other trails needs to be repeated.
There are many societies and groups other than the AHA/ACC that offer blood pressure guidelines. These include JNC, USPTF ACP, and ASH. It will be interesting to see if they also follow suite. If any of you have served on a committee you may have noticed that it is often the strongest and loudest voice that prevails, not necessarily the truth.