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People who have procedures to unclog their heart's arteries in the morning may do better than those who have them in the afternoon, according to a new study.
Those who had the artery-clearing procedure known as angioplasty done in the afternoon were more likely to need it repeated, and less likely to be alive in a year, than those who had it done in the morning, the study team reports in the American Heart Journal.
But it's hard to tell if this was because of health differences in patients who had angioplasties at different times of day, or because of what happened during the actual procedures.
"From this study alone we can't definitively determine what the cause of those worse outcomes was," Dr Warren Cantor, the lead author on the study and a cardiologist at Southlake Regional Health Centre in Newmarket, Ontario, told Reuters Health.
Blood flow diverted
In an angioplasty, a small balloon is used to clear a blocked coronary artery - the artery that supplies blood directly to the heart - and a stent is inserted to keep the artery clear.
Every year, more than 1 million people in the US undergo angioplasty, a procedure with a price tag in the thousands of dollars. Others can rely on medication to prevent heart attacks, while some get more invasive bypass surgery, in which blood flow is diverted around a blocked artery to feed the heart.
While some angioplasties are emergency procedures, others are scheduled in advance to stop patients with heart disease from getting worse, or to relieve their symptoms.
Cantor and his colleagues looked at what happened to almost 2 500 patients that had non-emergency angioplasties in Alberta, Canada. A little over half of those patients had the procedure between 7am and noon, while the others had it between noon and 6pm.
More advanced heart disease
Patients having an angioplasty in the afternoon tended to be worse off to begin with: they were sicker and had more advanced heart disease than patients who had angioplasty in the morning. It was unclear why the two groups had different characteristics, but patients who were already in the hospital - and therefore sicker, on average - were more likely to be scheduled in the afternoons.
They also were worse off after the procedure. Eighteen afternoon patients needed the angioplasty repeated or needed heart bypass surgery within the next month, versus 12 morning patients. After a year, 23 afternoon patients were dead, compared to 16 morning patients.
When they analysed their data, the researchers found that pre-treatment differences probably weren't the only reason for this difference. Other explanations could be that doctors and nurses are more rushed or tired in the afternoon or watching patients less closely overnight. Patients with morning procedures would likely be more stable, and thus less vulnerable to complications, by the time the overnight shift started.
Fatigue?
"It's not a crazy idea that this could potentially be due to fatigue," Dr Christopher Landrigan, who studies the effects of doctors' sleep deprivation on patient and doctor safety at Brigham and Women's Hospital in Boston, told Reuters Health. Landrigan was not involved in the study, which was funded by heart foundations and the government but also by some stent manufacturers.
Most people are sleepy for a while in the mid-afternoon because of the body's natural rhythms, he explained. Or, the doctors just could have been working for too long. Like truckers, he said, more time on the job for doctors is associated with worse performance.
Other studies have shown that angioplasties are more likely to go badly when they're done at night instead of during normal working hours. This effect has been shown for other procedures as well, including childbirth. But less is known about differences in treatment during the course of the work day, although one recent study suggested that morning colonoscopies caught more potentially cancerous polyps than those done in the afternoon.
While the results of the study are new and interesting, Cantor said, they're just a starting point for more research to come. The findings shouldn't force any changes to practice based on this study alone, he said.
Dr Harlan Krumholz, a professor at Yale University School of Medicine who was not involved in the study, also cautioned against reading too much into the findings. "It's way too early to say that this is really a problem," he told Reuters Health.
He said a bigger study at multiple hospitals would help researchers figure out why patients who had morning angioplasties fared better - if it was because of the patients themselves or something about their treatment. This study, he said, "gives us an alert to say that we should look more closely at this." - (Genevra Pittman, Reuters Health, June 2010)
