NEW ORLEANS – In children, ambulatory systolic daytime blood pressure load – the amount of time spent above the 95th blood pressure percentile for age and height – predicts cardiovascular target-organ damage, specifically diastolic dysfunction and arterial stiffness, according to an investigation from the American Heart Association Strategically Focused Research Network.
M. Alexander Otto/MDedge News
Dr. Elaine Urbina
Blood pressure load is considered in the 2017 American Academy of Pediatrics BP guideline, but the new findings add granularity on how to use it in practice. It’s part of an effort “to supply data to guide future guidelines, rather than arbitrarily picking a number – the 95th percentile – out of the sky,” said lead investigator and pediatric cardiologist Elaine Urbina, MD, director of preventative cardiology at the Cincinnati Children’s Hospital Medical Center, and senior author on the 2017 guideline.
In the absence of data linking specific BP levels to hard cardiovascular outcomes, as in adults, “we feel that load is helpful in determining risk categories for kids as we make decisions about who should get lifestyle counseling and who should get medication. It gets a little bit at blood pressure variability” and supplements the arbitrary 95th-percentile threshold, she said.
“If I saw a child with only a mild elevation of mean ambulatory blood pressure but they had increased load, it would prompt me to order an echocardiogram to look for target organ damage, which may then change my therapy from lifestyle to medication,” Dr. Urbina said at the joint scientific sessions of the American Heart Association Council on Hypertension, AHA Council on Kidney in Cardiovascular Disease, and American Society of Hypertension.
These conclusions come from an investigation of 339 healthy adolescents with a mean age of 15.6 years at six sites across the United States. Office BP was averaged over six readings during two visits, and ambulatory pressure was taken every 20 minutes over 26 hours. BP load was correlated with measures of left ventricular mass index (LVMI), systolic and diastolic function (E/e’ ratio), and pulse wave velocity (PWV), a gauge of arterial stiffness.
Overall, 215 subjects spent less than 25% of their time above the 95th percentile and were classified as the low-load group, 62 were above that mark 25%-49% of the time (mid-load group), and 62 were over it at least half of the time (high-load group).
Both load category and load as a continuous variable were significant predictors of arterial stiffness and diastolic dysfunction even after adjustment for age, sex, body mass index, and mean daytime ambulatory systolic blood pressure (P less than 0.0001).
Subjects in the high-load group, for instance, had a PWV above 5.5 m/sec, versus about 5.2 m/sec and less than 5 m/sec in the mid- and low-load groups, respectively. The high-load group had an E/e’ ratio above 7, versus 6 or less in the other groups. There was a trend for higher LVMI and reduced strain as well in the low- versus high-load groups.
Although the findings don’t indicate clinically relevant cardiovascular damage, children with higher loads seem to be “on the road to getting it,” Dr. Urbina said. Greater arterial stiffness means that high pulsatile pressures are transmitted to the microvasculature. Meanwhile, “the strength of the relationship with diastolic dysfunction worries me. It’s a precursor of heart failure with preserved ejection fraction, for which there are no effective therapies. We have to identify the precursors early and treat them so these kids don’t get heart failure later in life.”
Almost two-thirds of the subjects were white, most of the remainder were black, and 58% were boys. There were no statistically significant differences in age, race, sex, or body mass index across the groups, but overall, the children were overweight, and those with high BP load were more insulin resistant and had higher clinic and ambulatory BPs.
The team is assessing cognitive performance as a function of BP load.
Ambulatory pressures were taken by the Spacelabs OnTrak monitor.
The work was funded by the AHA and the National Institutes of Health. The investigators had no commercial disclosures.
SOURCE: Urbina E. Joint Hypertension 2019, Abstract P2056.