It’s impossible to plan the time a heart attack will occur. Who wants to plan on having a cardiac arrest anyway? But the results of a recent study seem to indicate a much higher rate of survival for patients, already hospitalized, who suffer cardiac arrest during week days and weekday evenings.The study is likely to lead to improved focus on cardiac care for hospitalized patients throughout the night and on weekends.

In the study, led by Mary Ann Peberdy, MD, Virginia Commonwealth University in Richmond, a typical day was divided into hourly segments, with the weekdays and evenings defined as Monday through Friday from 7:00 AM until 11:00 PM, nights from 11:00 PM until 7:00 AM, and weekends from 11:00 PM on Friday until 7:00 AM on Monday.

Data from in-hospital cardiac events was collected from 507 medical and surgical facilities and included incidences involving 86,748 adult patients for the years of 2000 through 2007.

Of these cardiac events, 58,593 occurred during day or evening hours, including weekends, and the remaining 28,155 events occurred during the night, also including weekend nights.

The rate of survival to discharge, meaning the patient recovered well enough to go home, was measured for each of the three time segments.

The highest rate of survival was seen in patients who suffered cardiac arrest during weekday daytime and evening hours (20.6%) as compared to those who suffered cardiac arrest on weekends (17.4%) and those occurring during week nights (14.6%) and weekend nights (14.8%).

Many factors are thought to influence the rate of survival to discharge, including biological factors as well as staffing and operational factors. For complete details of the study, please see JAMA’s February 20 issue.