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Common anesthesia may raise long-term risk of heart attack

Kathleen Blanchard's picture
Heart attack

Nitrous oxide anesthesia may increase the chances of heart attack, even for those at low-risk.

Research suggests patients receiving the widely used anesthesia during surgery and at the dental office are at higher risk of suffering heart attack or myocardial infarction that persists years later, compared to nitrous-oxide free surgeries.

Scientists at the Royal Melbourne Hospital and colleagues who conducted a study as a follow-up to previous research found a 60 percent increased risk of heart attack among patients who received nitrous oxide, compared to a group not given the anesthesia.

The analysis, conducted by Dr. Kate Leslie of Royal Melbourne Hospital and colleagues, included 2,050 patients undergoing noncardiac surgery who were part of the ENIGMA trial that found higher rates of myocardial infarction in patient given nitrous oxide gas for anesthesia. As a follow-up, researchers found 19 percent of patients had died and 4.5 percent had a myocardial infarction 3.5 years later.

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The findings, published in the journal Anesthesia & Analgesia, also found more deaths in the group of patients given nitrous oxide. In the study there were nine deaths among those given the anesthetic, compared to 3 who did not. In the ENIGMA trial, 30 patients had heart attack compared to ten patients not given the gas.

The study authors write, "The exact relationship between nitrous oxide administration and serious long-term adverse outcomes requires investigation in an appropriately designed large randomized controlled trial."

Even after adjusting for other risk factors, researchers still found a 60 percent higher risk of heart attack associated with nitrous oxide anesthesia. Most of the patients studied were at low risk for myocardial infarction, leading the researchers with unanswered questions about the safety of the commonly used anesthesia.

Anesthesia & Analgesia: doi: 10.1213/​ANE.0b013e3181f7e2c4
"Nitrous Oxide and Long-Term Morbidity and Mortality in the ENIGMA Trial"