STREAMING NOW: Watch Now

Both the "top" and "bottom" blood pressure numbers can increase your risk of heart attack and stroke, study says

People who forget to look at the bottom number in a blood pressure reading may want to check again. When uncontrolled, both measures of blood pressure can in...

Posted: Jul 18, 2019 5:36 PM

People who forget to look at the bottom number in a blood pressure reading may want to check again. When uncontrolled, both measures of blood pressure can increase the risk of heart attack and stroke, according to a study published Wednesday in the New England Journal of Medicine.

Blood pressure is the force of blood flow in arteries, veins and capillaries. When that force is too high, it's considered hypertension, defined as having a consistent blood pressure reading greater than 130/80. The top number, called systolic pressure, is the pressure of vessels when the heart beats and pumps out blood, while the bottom number, called diastolic pressure, is the pressure in blood vessels when the heart is at rest and filling up with blood.

Researchers in this study found that high systolic pressure placed patients at greater risk of heart attack and stroke, but that uncontrolled diastolic pressure could also adversely affect cardiovascular health. On average, patients with systolic blood pressure of 160 had a 4.8% risk of having a heart attack or stroke, while patients with a diastolic blood pressure of 96 had a 3.6% risk.

"There has been a pendulum-swing over the years toward the view that systolic hypertension is the only thing that matters," said Dr. Alexander Flint, the study's lead author and a stroke specialist at Kaiser Permanente, in an email. "Doctors and patients should make sure that both systolic blood pressure and diastolic blood pressure get attention when it comes to diagnosing and treating hypertension."

The findings don't come as a surprise to hypertension experts like Dr. Karol Watson, co-director of the UCLA Program in Preventive Cardiology.

"Fifty years ago, most people thought diastolic BP was more important than systolic BP," Watson, who was not involved in the study, said in an email. "But diastolic BP has always been important, and increasing levels do confer increased risk. This study verified that."

The study analyzed existing data on 36 million outpatient blood pressure readings from 1.3 million adults, listed in an electronic medical record. Over the course of eight years, from 2009 and 2016, the researchers determined risk based on whether patients had their first episode of a heart attack or stroke during that time. Researchers also classified people with hypertension using two thresholds -- greater than 140/90 or greater than 130/80 -- to see if the risk of cardiovascular events changed based on the threshold used.

In 2017, the US guidelines for high blood pressure changed, dropping the threshold from 140/90 to 130/80 -- a move considered controversial in the medical community.

Almost 19% of blood pressure measurements met the 140/90 threshold, while 44% of measurements met the 130/80 threshold. The risk of a heart attack or stroke was similar across both thresholds, the researchers found.

"People spent a lot of time debating whether the lower threshold made sense," Watson said. "This study validates the lower threshold."

But blood pressure that's too low can be just as dangerous. In the study, people categorized with the highest and lowest diastolic blood pressures were the ones who had the highest risk of heart attack and stroke. Systolic blood pressures of less than 90 are also harmful and can put people into shock, a state of low blood flow and oxygen delivery to vital organs including the brain.

"Nothing magic happens at 140/90 or at 130/80. Higher [blood pressure] is worse, and lower is better, until you get too low," David Goff, Director of Cardiovascular Sciences for the National Heart, Lung, and Blood Institute, said in an email. Goff was not involved in the study. "These results confirm previous findings over the past several decades that the relationship of blood pressure with heart disease risk is graded."

The bottom line: Systolic and diastolic blood pressures should be "tightly controlled" and follow the 2017 guidelines, Flint said.

The study was observational and could only evaluate the relationship, not the cause, between blood pressure and cardiovascular events.

It also doesn't directly address the benefit of treating hypertension, Goff said.

There are medicines that can treat both types of hypertension, but lifestyle factors are also important in keeping blood pressure in a healthy range. These include avoiding smoking, eating healthy, limiting alcohol use and exercising.

In the US, about one third of adults have hypertension according to the US Centers for Disease Control and Prevention. Heat disease is the leading cause of death worldwide.

"At present, only about half the people in the US with hypertension are controlled." Goff said. "A major focus for us should be on improving blood pressure control to reduce risk of heart disease and stroke."

Huntsville
Mostly Cloudy
58° wxIcon
Hi: 72° Lo: 52°
Feels Like: 58°
Florence
Partly Cloudy
60° wxIcon
Hi: 68° Lo: 51°
Feels Like: 60°
Fayetteville
Partly Cloudy
60° wxIcon
Hi: 70° Lo: 48°
Feels Like: 60°
Decatur
Partly Cloudy
58° wxIcon
Hi: 70° Lo: 53°
Feels Like: 58°
Scottsboro
Partly Cloudy
60° wxIcon
Hi: 73° Lo: 54°
Feels Like: 60°
WAAY Radar
WAAY WAAY-TV Cam
WAAY Temperatures

 

Alabama Coronavirus Cases

Cases: 531094

Reported Deaths: 10978
CountyCasesDeaths
Jefferson765441522
Mobile40979804
Madison34763503
Tuscaloosa25781452
Montgomery24331589
Shelby23431249
Baldwin21135308
Lee15886171
Calhoun14505314
Morgan14300279
Etowah13834353
Marshall12222223
Houston10571281
Elmore10061205
Limestone9964151
Cullman9670193
St. Clair9657243
Lauderdale9428241
DeKalb8831186
Talladega8223176
Walker7236277
Autauga6920108
Jackson6813112
Blount6661137
Colbert6301134
Coffee5512119
Dale4831111
Russell441238
Chilton4294112
Franklin425682
Covington4121118
Tallapoosa4029152
Escambia393476
Chambers3563123
Dallas3551151
Clarke351061
Marion3119101
Pike310877
Lawrence300298
Winston274472
Bibb260764
Geneva250077
Marengo249764
Pickens234461
Barbour230857
Hale222977
Butler215969
Fayette212462
Henry188744
Cherokee184945
Randolph180241
Monroe177440
Washington167339
Macon159250
Clay156256
Crenshaw152357
Cleburne148941
Lamar142535
Lowndes138853
Wilcox127130
Bullock123041
Conecuh110529
Perry107726
Coosa107228
Sumter104532
Greene92334
Choctaw60624
Out of AL00
Unassigned00

Tennessee Coronavirus Cases

Cases: 854360

Reported Deaths: 12276
CountyCasesDeaths
Shelby959681622
Davidson89465938
Knox50796635
Hamilton44378495
Rutherford43100435
Williamson28040217
Sumner24052349
Montgomery20315227
Wilson18838235
Out of TN1842298
Unassigned17005134
Sullivan16846295
Blount15513193
Bradley15062150
Washington14623245
Maury13517172
Sevier13408175
Putnam11398175
Madison11185242
Robertson9768131
Anderson8768172
Hamblen8616173
Greene7889156
Tipton7371102
Coffee6911122
Dickson6841112
Cumberland6748133
Carter6639158
Gibson6533146
McMinn651898
Bedford6512129
Roane6302105
Jefferson6222124
Loudon614069
Hawkins6110107
Lawrence595387
Monroe585595
Warren554681
Dyer5429106
Franklin515490
Fayette509076
Cheatham455856
Obion454196
Cocke451199
Lincoln436663
Rhea435375
Marshall419958
Campbell415763
Weakley414765
Giles3999100
Henderson379576
White366070
Carroll362283
Macon362278
Hardin357868
Hardeman352964
Lauderdale319644
Henry319376
Claiborne318173
Scott313645
Marion312847
Overton301661
Wayne296234
Hickman284446
McNairy282554
DeKalb280354
Smith277939
Haywood271462
Grainger263050
Morgan250239
Trousdale250222
Fentress242347
Johnson240939
Chester214851
Bledsoe214611
Polk208224
Unicoi204249
Crockett203248
Cannon192331
Union190734
Humphreys180327
Grundy179334
Lake170426
Sequatchie170229
Benton166740
Decatur158939
Lewis158226
Meigs139025
Stewart132528
Jackson132336
Clay110331
Houston109533
Perry106728
Moore101217
Van Buren84823
Pickett76024
Hancock59112

Community Events