Circulation: Off-hour MI presentation did not affect mortality rate

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Despite slightly fewer primary PCIs, overall revascularizations and significantly longer door-to-balloon times, patients presenting with acute MI (AMI) during off-hours had in-hospital mortality similar to those presenting during regular hours, according a study published online ahead of the May 13 print issue of Circulation.

Using a contemporary national clinical registry, Hani Jneid, MD, from Massachusetts General Hospital and Harvard Medical School in Boston, and colleagues examined the differences in medical care and in-hospital mortality among AMI patients admitted during regular hours (weekdays 7 a.m. to 7 p.m.) versus off-hours (weekends, holidays and 7 p.m. to 7 a.m. weeknights).

The study cohort included 62,814 AMI patients from the Get With the Guidelines–Coronary Artery Disease database admitted to 379 hospitals throughout the U.S. from July 2000 through September 2005, according to the researchers.

Overall, the investigators said that 33,982 patients (54.1 percent) arrived during off-hours. Compared with those arriving during regular hours, eligible off-hour patients were slightly less likely to receive primary PCI, had longer door-to-balloon times (median, 110 vs. 85 minutes) and were less likely to achieve door-to-balloon ≤90 minutes, the authors wrote. Arrival during off-hours was associated with slightly lower overall revascularization rates, according to the researchers.

Jneid and colleagues found that off-hours STEMI patients had a 66 percent reduced chance of having a door-to-balloon time of 90 minutes or less.

However, the investigators found no measurable differences in in-hospital mortality between regular hours and off-hours in the overall AMI, STEMI and non–STEMI cohorts.

The researchers noted similar observations across most age and sex subgroups, as well as with an alternative definition for arrival time (weekends/holidays versus weekdays).

"We thus argue that, although … campaigns to reduce time to reperfusion are laudable, improvements in [door-to-balloon] times should be complemented by multifaceted approaches to optimize multiple levels of medical care in parallel and thus impart the largest influence on national [acute MI] mortality,” the authors wrote.

The authors noted the study’s limitations: the hospitals included were self-selected and may not represent national care patterns and clinical outcomes; the researchers did not have pre-hospital or post-discharge data; eligibility for treatment was dependent on the accuracy of the medical records; and there may have been unmeasured confounders.