In a small, retrospective study, Mayo Clinic researchers found that 8% of heart patients who did not wait to have teeth pulled suffered major adverse health outcomes, such as a heart attack, stroke, kidney failure or death.
"Guidelines from the American College of Cardiology and American Heart Association label dental extraction as a minor procedure, with the risk of death or non-fatal heart attack estimated to be less than 1%," study co-author Dr Mark Smith said in a statement. "Our results, however, documented a higher rate of major adverse outcomes [with the extractions]."
Understanding the risks
Such extractions are commonly done ahead of some types of heart surgery to lower the chances of infection during the procedure or avoid inflammation of the inner layer of the heart after the operation, the researchers noted.
However, the study didn't pinpoint what risks might be posed by postponing major dental care until after heart surgery. The study also didn't prove a cause-and-effect relationship.
Still, the finding "does help us to understand the risk we're exposing patients to when they get their teeth extracted before their heart surgery," said study co-author Dr Kendra Grim, an anaesthesiologist at the Mayo Clinic in Rochester, Minn. "It opens up a lot of different avenues for research and discussion."
At issue is what to do with patients who have both dental problems and heart issues. A combination of these two conditions isn't uncommon, explained Dr Ann Bolger, a professor of medicine at the University of California, San Francisco, and a spokeswoman for the American Heart Association.
"Given the frequency of risk factors that poor oral health and cardiovascular disease share, such as age, smoking and diabetes, the fact that they overlap is not a surprise," Bolger said.
But the combination can be dangerous.
Bacteria in the bloodstream
"We know that patients with poor dental health are at higher risk of having bacteria in the bloodstream, which can cause infections in the heart valve," Grim explained.
Previous research suggests that patients with infected artificial heart valves have a 38% higher risk of dying, according to background information in the study.
But the authors of the new study write that it's not clear whether it's a good idea to get dental treatment before heart surgery. To try to get closer to an answer, they examined the medical records of 205 patients who had teeth removed before undergoing cardiac surgery.
Of those patients, a total of 8% (16 people) experienced a heart attack, stroke, kidney failure or death. Twelve patients died within 30 days after their teeth were removed– including six people who died before their cardiac operation and six who died after heart surgery, the investigators found.
What's going on?
Risk of death higher than expected
The condition of the patients may have been so poor that they had trouble tolerating anaesthesia during a dental procedure, Grim said. As to whether things would have been different if patients hadn't undergone dental treatment, Grim said it's unclear.
Still, the risk of death and other medical problems was higher than the study authors expected, she noted.
"If a tooth is painful and obviously infected, it must be dealt with," Grim said. "The dental procedures discussed here, and that are most common, are prophylactic [preventive]. That is, the extraction of an infected tooth may not be an urgent dental issue, but when the patient has [scheduled] heart surgery – particularly valve replacement surgery – pre-emptive dental imaging and extractions are often performed."
For now, the study isn't prompting any new guidelines or rules. For one, researchers don't know exactly where the increased risk may originate. It's not easy to figure out what to do except carefully control pain or high blood pressure resulting from a dental procedure, Bolger said.
"This is an interesting study that identifies a gap in our understanding of the risks of this practice. But it does not prove that doing the opposite would improve outcomes," Bolger said. "This work will need to be followed by additional studies before we know with more certainty."
The study appears in the March issue of The Annals of Thoracic Surgery.