Study finds morning heart attacks can cause more damage By Pure
Matters In fact, if the heart attack happens between 6 a.m. and
noon, it is likely to damage about 20 percent more heart muscle
than a heart attack occurring in the afternoon or evening, the
researchers added. "It is well-known for several decades that
the incidence of heart attack is variable across the time of the
day, with higher incidence in the early morning hours," said
lead researcher Dr. Borja Ibanez, from the National Center for
Cardiovascular Research in Madrid. It has been speculated,
though not proven, that the body's circadian clock triggers the
release of substances into the bloodstream that make the heart
more prone to a heart attack at certain times of the day, he
added. "What was completely unexplored was the effect of the
time of the day of onset of the heart attack on the extent of
heart muscle death," Ibanez said. "This is the very first
examination showing that the human heart has a variable
tolerance to ischemia according to