Many patients who survive myocardial infarction (MI) don’t consistently take medications prescribed to prevent a second MI, a large U.S. study suggests.¹

Researchers asked 7,425 patients how often they took all the drugs physicians prescribed shortly after their heart attack, and about 2,150 of them confessed to following doctors’ orders only some of the time.

While each patient may have unique motivations for deciding whether or not to take medications, it’s not uncommon for people who skip doses or fail to fill prescriptions to do so because they misunderstand the role of the medications in preventing another heart attack, fear side effects, or lack funds to pay for drugs, lead author Robin Mathews, MD, told Reuters Health in an email.

“Ultimately, regardless of the reason, patient non-adherence to medications after a heart attack has been associated with poor outcomes—these can include repeat hospitalization, progression of their underlying disease, or even reduced survival,” said Dr. Mathews, a cardiologist and researcher at Duke University Medical Center in Durham, North Carolina.

Dr. Mathews and colleagues reviewed drug compliance for MI patients treated at 216 U.S. hospitals between April 2010 and May 2012. During their hospital stay, all of the patients had percutaneous coronary intervention (PCI) and were prescribed antiplatelet therapy.

Six weeks after their MI, 71 percent of study participants said they consistently took their medications as prescribed. But 25 percent said they did so only occasionally, and another 4 percent said they used medications rarely.

Among the people least likely to take their medicine, most cited forgetfulness and about 20 percent said they didn’t tell their doctor when they stopped taking drugs due to side effects.

While the patients who were least compliant with medication were more likely to die or be hospitalized again within two months of their heart attack, the difference wasn’t large enough to rule out the possibility that this was due to chance.

Because researchers didn’t use data from patients who died within six weeks of their MI, it’s possible that early medication non-compliance was underreported, the authors acknowledge in the article.

In addition, they only checked medication adherence at one point in time, and they relied on patients to truthfully report how often they took prescribed drugs.

“There’s a lot going on in the days following a heart attack and often times the discussions about why each medication is important gets diluted by all of the other issues occurring in the hospital at the same time,” said Steven Baroletti, director of pharmacy at MetroWest Medical Center in Framingham, Massachusetts.