Mortality Following Stroke as an Example of the Importance of Raised Blood Pressure as a Mediating Mechanism of Aging

Raised blood pressure, hypertension, is an important mechanism involved in the transmission of age-related damage from low-level biochemical changes to high level structural damage and organ failure. The importance of blood pressure in this context is why significant reductions in mortality rate can be achieved by means of lowering blood pressure, by overriding cellular reactions or cell signaling, that fail to address any of the underlying root causes of hypertension. These root causes are largely the set of biochemical changes that act to stiffen blood vessels, as hypertension appears to be near entirely a consequence of loss of elasticity in the vascular system. They include cross-linking, cellular senescence, and a range of less well understood shifts in the capabilities and behavior of vascular smooth muscle cells. If reductions in blood pressure now can achieve useful results, imagine the far greater benefits that will result once rejuvenation therapies exist capable of repairing the low-level damage that causes vascular stiffness. Not only hypertension will be addressed, but also all of the other issues that this damage in cells and tissues gives rise to.

Treating high blood pressure in stroke survivors more aggressively, could cut deaths by one-third, according to new research. "The potential to reduce mortality and recurrent stroke is immense, because more than half of all strokes are attributable to uncontrolled high blood pressure." In the AHA/ACC guideline for hypertension, released in 2017, the threshold for stage 1 hypertension, or high blood pressure was changed to at or above 130 mmHg for the top number or 80 mmHg for the bottom number. The previous threshold for high blood pressure was, at or above 140/90 mmHg.

Overall, while many more people will be diagnosed with hypertension under the new guideline, there will be only a small increase in the percentage of people who require medication. However, blood pressure-lowering medications are recommended for all stroke survivors with blood pressures of 130/80 mmHg or higher, and additional drugs if needed to reduce blood pressure below that threshold.

In the new study, researchers used data from the National Health and Nutrition Examination Surveys to estimate the nationwide impact of applying that approach. The surveys, conducted between 2003 and 2014, included blood pressure measurement and asked participants about their stroke history and blood pressure treatment. If clinicians fully shift from the previous guidelines to the new ones, the researchers calculated the impact on stroke would be: (a) a 66.7 percent increase in the proportion of stroke survivors diagnosed with hypertension and recommended for pressure-lowering medication (from 29.9 percent to 49.8 percent); (2) a 53.9 percent increase in the proportion of stroke survivors already taking pressure-lowering drugs who will be prescribed additional medication to reach their target blood pressure (from 36.3 percent to 56 percent); and (3) a 32.7 percent reduction in deaths, based on the difference in death rates in stroke survivors above and below the 130/80 mmHg target blood pressure (8.3 percent vs. 5.6 percent).



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