Some research has found that people may be less likely to survive a heart attack if they are treated during hospital “off-hours.” But a new study suggests that is not the case - at least for people treated at larger medical centers well-equipped for handling heart attack victims.

Italian researchers found that of 3,000-plus patients who had a heart procedure done at their network of 28 hospitals, those treated during off-hours - at night, over the weekend or on holidays - fared just as well as those treated on weekdays.

Six percent of the off-hours patients died in the hospital, versus 7 percent of “regular-hours” patients. After one year, 8 percent of off-hours patients and 10 percent of those treated during regular hours had died.

When the researchers weighed other factors - like patients’ overall health and the severity of their heart disease - the timing of patients’ treatment remained unrelated to their survival odds.

All of the patients had suffered what is known as an ST-segment elevation heart attack - the more serious form of heart attack in which an artery supplying the heart with blood becomes completely blocked off.

And most were treated in the network’s nine intensive cardiac care units, which perform a high volume of so-called angioplasty procedures each year (at least 80).

During the procedure, a thin, balloon-tipped catheter is threaded into the blood vessels to move aside the blockage causing the heart attack. Then a metal mesh tube, or stent, is left behind to prop open the artery.

This treatment can be life-saving, but some studies over the years have found that they appear less effective for patients treated during off-hours.

Experts have pointed to factors like longer delays to care, hospital staff fatigue, and having less-experienced staff on duty during off-hours.

Dr. Gianni Casella, the lead researcher on the new study, said he believes that hospitals’ organizational structure is the key.

In past studies where off-hours patients fared more poorly, he told Reuters Health in an email, their time to treatment was generally significantly longer.

In the current study, there was a small difference in time to treatment between patients who got stents during off-hours or regular hours, said Casella, a cardiologist at Maggiore Hospital in Bologna.