MI outcomes may be worse when treated during off-hours

Patients who present with heart attacks during off-hours may have worse outcomes than patients who seek treatment during regular hours, according to an analysis published online Jan. 21 in BMJ. Patients with acute MI had higher mortality rates and STEMI patients had longer door-to-balloon times.

Investigators led by Atsushi Sorita, MD, of the Mayo Clinic in Rochester, Minn., analyzed 48 studies from around the world involving 1,896,859 patients that assessed the association between the time patients presented with acute MI and mortality or door-to-balloon times. They defined off-hours as weekends and nighttime. Regular hours were weekdays and daytime. Presentation time was considered time of hospital arrival, admission to hospital or start of PCI. Mortality was either in-hospital or 30-day mortality.

Presentation with acute MI during off-hours was associated with higher short-term mortality (odds ratio [OR] 1.06). STEMI patients presenting during off-hours were not as likely as patients presenting during regular hours to undergo PCI within 90 minutes (OR 0.4). Door-to-balloon times were 14.8 minutes longer as well. STEMI patients outside North America were at higher mortality risk during off-hours. Their analysis also found that mortality differences between off-hours and regular hours have increased over the past few years.

Sorita and colleagues wrote that possible reasons for the associations include the availability of skilled cardiac care staff, availability of diagnostic testing, fewer patient care staff and sleep deprivation. There also may not be 24-hour PCI availability, which could account for the differences in door-to-balloon times. Other studies, they continued, found that patients who presented during off-hours tended to be sicker.

The authors explained that their findings potentially have enormous implications. About 900,000 patients seek treatment at U.S. hospitals for acute MI every year, and two-thirds of them present during off-hours.

“[A]nnual excess deaths in acute myocardial infarction due to off-hour presentation would be about 2,300 for in-hospital deaths and 3,800 for deaths within 30 days,” they wrote.

“Efforts to improve systems of care should ensure that comparable outcomes are achieved for patients regardless of the time of day or day of the week that patients present to the healthcare system,” they continued.