Heart attacks that occur between 6 a.m. and midday are more dangerous than those that occur at another time of the day, researchers have found.
The Spanish researchers, whose results were published in the journal Heart, said that the a.m. heart attacks left a larger amount of dead tissue in the heart. This is the first study that has examined the comparative seriousness between morning heart attacks and those at other times of day.
The 24-hour body clock we all have affects some of our cardiovascular physiological processes, including the incidence of heart attack. Those processes, the researchers said, are strongest when we wake up in the morning.
In a study of patients at Hospital San Carlos, Madrid, from 2003 to 2009, the researchers worked out how much dead tissue was stored in each patient’s heart, and they found a startling difference between different periods of the day.
The amount of dead tissue was 21 percent higher in people wh o had a morning heart attack, compared with those who suffered one between midnight and 6 a.m. The study focused on people who had a heart attack in which the the blood to the heart is blocked for a long time. This kind of attack is known as STEMI.
Unfortunately, most of the patients who were part of the survey had their heart attacks in the morning. Of 811 patients, 269 had morning heart attacks, 240 had them between noon and 6 p.m., 161 had them between 6 p.m. and midnight, and 141 suffered one between midnight and 6 a.m.
