Blunted morning blood pressure (BP) surges, not excessive surges as previous research has suggested, predict an increased risk of cardiovascular (CV) events among hypertensive patients, a new study found.
Italian investigators who studied 3,102 initially untreated subjects with essential hypertension found that those with a pre-awakening systolic BP surge in the first quartile (below 9.5 mm Hg) had a 71% increased risk of major CV events compared with subjects in the highest quartile (greater than 27.5 mm Hg), after adjusting for numerous variables, including left ventricular hypertrophy and estimated glomerular filtration rate. In addition, subjects in the bottom quartile of sleep-trough systolic BP surge (19.5 mm Hg or less) had a 66% increased risk of events compared with those in the top quartile (greater than 36.0 mm Hg).
A blunted day-night BP dip was associated with a blunted morning BP surge and vice versa.
The researchers, led by Paolo Verdechhia, MD, of the Hospital of Assisi in Assisi, Italy, reported their findings in Hypertension (2012;60:34-42).
They noted that none of the studies looking at morning BP surge were specifically conducted in large cohorts of hypertensive patients who were untreated at the time of 24-hour ambulatory BP monitoring, “thus avoiding the potential interference of anti-hypertensive treatment and time of administration.”
Dr. Verdechhia and his colleagues stated that contrary to their expectations, the magnitude of the early morning BP surge did not contribute to improvement in cardiovascular risk stratification.
With respect to study limitations, the researchers noted that their investigation was conducted in a white population, so results should not be extended to different ethnic groups.
For the study, the researchers determined the pre-awakening morning BP surge as the difference between the average BP during the two hours after awakening and the average BP during the two hours before awakening. They determined the sleep-trough BP surge as the difference between the average BP during the two hours after awakening and the lowest nighttime BP.
They considered major CV events to be a composite of cardiovascular death, nonfatal myocardial infarction, nonfatal stroke, and heart failure requiring hospitalization.