Rapid drop in air pressure may trigger heart attack

By Anthony J. Brown, MD

NEW YORK (Reuters Health) – A rapid drop in air pressure —
as opposed to cold weather — may trigger some heart attacks,
research shows. According to a study published this month, the
incidence of heart attack, but not stroke, is increased in the
24 hours after a rapid fall in barometric pressure.

“Previous reports have shown that there are more (heart
attacks) in the wintertime,” lead author Dr. Philip D. Houck,
from The Scott & White Hospital and Clinic in Temple, Texas,
told Reuters Health. But, this does not seem to relate to cold
temperatures because even warm locations, such as Hawaii, have
shown an increase in heart attacks during the winter, he

Houck and others correlated atmospheric pressure data with
the occurrence of heart attack and stroke in central Texas
between 1993 and 1996. A total of 1327 heart attack patients
and 839 stroke patients were identified.

The fall and winter showed the greatest variability in
atmospheric pressure readings, the report indicates. As noted,
an increased risk of heart attack, but not stroke, was seen in
the day following a drop in air pressure.

“My experience taking care of patients over the years told
me that the day after a major weather event, like a
thunderstorm, we would see a cluster of heart attacks,” Houck
said. “Our study now shows that a relationship does exist. The
more the pressure falls, the greater the chance someone has of
having a heart attack the next day.”

Changes in atmospheric pressure don’t explain all heart
attacks, the researchers say, and the risk is likely highest in
individuals with heart disease.

“An atherosclerotic plaque may be a lot like a
bathysphere,” Houck said. As a bathysphere descends in the
water, pressure accumulates. When they fail, however, it
typically occurs during ascent when pressure drops. In a
similar way, changes in barometric pressure may cause plaque
rupture, resulting in an MI (heart attack).”

SOURCE: American Journal of Cardiology July 1, 2005.