High-Sensitivity Version of Common Blood Test May Predict Early Onset of Hypertension

A study analyzing blood samples from over 5,000 people suggests that a more sensitive version of the standard blood test for cardiac troponin T (CT-T)—long used to verify heart muscle damage from heart attacks—could help identify people on the verge of developing hypertension well before it can be detected with a blood pressure machine.

High blood pressure’s stealthy onset, its variability over time, and the need to re-check over multiple visits before making a diagnosis, have hampered efforts to treat and prevent this disease. Results of the new study using a high-sensitivity CT-T test, led by Johns Hopkins University (Baltimore, MD, USA) investigators, showed that people with subtle elevations in CT-T — below levels detectable with the standard test — were more likely to be diagnosed with hypertension within a few years. The test could also identify those at risk for left ventricular hypertrophy, the abnormal thickening of the lower left chamber of the heart, a common consequence of untreated high blood pressure. Therefore, subtle increase in CT-T levels may have value as a marker predicting high blood pressure and subclinical heart damage.

“Identifying those at risk for hypertension as well as those in the earliest stages of the disease would allow us to intervene much sooner, either with lifestyle changes or medication, before the condition develops fully and has had a chance to damage organs,” said first author Bill McEvoy, MBBCh, MHS, assistant professor at the Johns Hopkins University School of Medicine.

The standard CT-T test is relatively inexpensive (USD 10–20) and is the gold-standard test for cardiac muscle damage from recent or ongoing heart attacks, indicating whether someone with chest pain or other cardiac symptoms is having a heart attack. However results are often “normal” for many with other forms of cardiac damage unrelated to heart attacks. The new version is calibrated to detect far lower CT-T levels, even trace amounts released by heart cells injured by spikes in blood pressure that come and go unnoticed, often for years. It is currently used across Europe, but not yet available for clinical use in the USA.

“Our data suggest that the high-sensitivity CT-T test could flag people with normal blood pressure in the doctor’s office who are at high risk for hypertension and other poor outcomes,” said senior study investigator Elizabeth Selvin, PhD, MPH, professor at Johns Hopkins Bloomberg School of Public Health. For example, people whose blood pressures yo-yo during the day or those whose pressures don’t decrease as normal during sleep, can be missed during regular blood pressure checks. Such people are prone to developing silent heart damage from erratic blood pressure and often progress to hypertension within a few years. “That group may benefit from more aggressive monitoring, including a 24-hour blood pressure monitor,” said Prof. Selvin.

If further clinical trials affirm the reliability of the high-sensitivity CT-T test as a screening tool for subclinical or future hypertension, it could also help clinicians ward off other devastating complications, including kidney brain and eye damage.

The summary of the findings, by McEvoy JW et al., were published online ahead of print July 7, 2015, in the journal Circulation.

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