January 7th, 2013
After Hurricane Katrina, Timing of Heart Attacks Shifted in New Orleans
Larry Husten, PHD
Prior to Hurricane Katrina, myocardial infarctions (MIs) in New Orleans followed a well-known circadian and septadian (today’s word of the day, meaning day of the week) pattern, with predictable increases on Mondays and in the morning hours. Now a new study from the American Journal of Cardiology finds that the notorious 2005 hurricane dramatically altered that pattern for at least three years, shifting the pattern to a much greater than expected occurrence over nights and weekends.
Researchers analyzed data from MI patients treated at Tulane University Health Sciences Center (TUHSC) and found startling differences in the timing of MI before and after Katrina. On a daily basis, they found a significant decrease in morning MIs but a twofold increase in evening MIs. On a weekly basis, they found a greater than twofold decrease in Monday MIs, balanced by an increase on weekends, especially Saturdays.
There were other differences in the patient population, undoubtedly reflecting the changes to New Orleans caused by Katrina. After Katrina, MI patients were more likely to be smokers, unemployed, and uninsured. MI patients were also two years younger after the hurricane. As stress is an acknowledged trigger for MI, this may help explain some of the demographic changes.
The tremendous amount of stress after the hurricane may help explain the time shifts as well. The stress associated with waking up in the morning, and in particular waking up on Monday morning, is known to provoke the biological changes that underlie the established daily and weekly variations. The investigators speculated that, after Katrina, waking up and going to a job may actually have functioned as “a distraction from stresses associated with homelessness and other life alterations” caused by the hurricane.
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