High blood pressure found to hike heart attack risk when it's cold

MUNICH, Germany -- People with high blood pressure seem to be morevulnerable to heart attacks when the temperature drops, new researchshows.

The findings, presented Monday at a conference of the EuropeanSociety of Cardiology, are not surprising because cold weather makesthe blood vessels constrict, making it harder for blood to movethrough. But the study is the first to document that variations inthe weather increase heart attack occurrence in people with highblood pressure.

The two-year study, conducted by scientists at the University ofBurgundy in France, examined 748 people with heart attacks admittedto local hospitals. The researchers matched the hospital admissionwith weather information covering the same period.

Of those in the study, 50 percent were being treated for highblood pressure or had at some time suffered from the condition.

Overall, heart attacks were more frequent when the temperaturedropped below 39.2 degrees Fahrenheit. But a closer analysis revealedthis was only true for people with high blood pressure. There weredouble the number of heart attacks among them when the temperaturedropped below the threshold.

Heart attacks also went up in hypertensive people when thetemperature dropped by more than nine degrees on the day of theirattack, regardless of how cold it was.

Blood pressure rises when it gets colder because the blood vesselsnarrow to preserve body heat. Those with hypertension start at ahigher blood pressure, which is more strenuous for the heart.

The study highlights the special vulnerability that people withhigh blood pressure have to cold weather and underlines theimportance of getting their blood pressure down to normal levels,said Dr. David Faxon, chief of cardiology at the University ofChicago and a former president of the American Heart Association.

AP