A heartburn medicine for acid reflux used by a considerable portion of the U.S. population has been implicated with a higher risk of heart attack, according to a recent study. Prilosec, also known by its generic name omeprazole, is a well-known example of this class of medications known as proton pump inhibitors, or PPIs, used to reduce the acidity inside the stomach. PPIs are commonly used to treat symptoms like heartburn as well as acid reflux or gastroesophageal reflux disease.

Researchers Study Heartburn Treatment and Heart Attack Risk

The acid reflux study was conducted by researchers from the Stanford University School of Medicine. Researchers data-mined the electronic health records from two large databases of clinical records of almost 3 million persons, looking for previously unrevealed correlations.

They compared the rates of heart attack in patients taking PPIs or acid reflux medication to that of patients who had heartburn but did not take a PPI like Prilosec. Researchers were able to determine an association between the use of PPIs like Prilosec and an increased incidence of heart attack. Adults who took PPIs were about 20 percent more likely to suffer heart attack than those who did not take PPIs. The study also found no elevation of heart attack risk in patients who took an older type of heartburn treatment medication called H2 blockers.

In a separate body of evidence, the researchers also found a link between Prilosec and other adverse cardiovascular events. They considered current results from an ongoing study of 1,500 patients with certain potentially cardiac symptoms. Within this patient population, the researchers searched these results for instances of several different types of adverse cardiac events, not just heart attack. The researchers found that with PPI heartburn treatment, patients had more than double the incidence of major adverse cardiovascular events.

Despite the impressive sample size, the researchers cautioned that the evidence still does not prove a causal relationship between Prilosec and heart attack. They discouraged persons now taking heartburn treatment from discontinuing their medication without first talking to their physicians about other options.

Prilosec and Heart Attack

What causes this correlation between Prilosec use and heart attack is not known. A few theories have been put forward, but none of them has won general acceptance.

More recently, a study published in the journal Circulation in 2013 proposed that PPIs might cause a swath of biochemical effects that could ultimately cause a reduction in levels of nitric oxide in endothelial tissue, such as blood vessels.

That study led to the current medical record study at Stanford. In combing millions of medical records, the Stanford researchers sought evidence of a relationship between a decrease in nitric oxide and an increase in heart attack rates. And in fact, the Stanford researchers found in acid reflux medication users a parallel between the higher instance of heart attack and the reduced levels of nitric oxide.

No fewer than 20 million Americans treat reflux symptoms and conditions with PPIs like Prilosec. In an average year, PPIs are prescribed 100 million times in the U.S. And now that PPIs are sold over the counter, they are more readily available to consumers than ever before.

Researchers say the results of their studies raise the possibility that an increased risk of heart attack is an inherent characteristic of Prilosec, possibly exposing millions of Prilosec patients to that risk.