People who take medications as prescribed are more than twice as likely to not have complications after heart procedures, according to a study released Monday.

The study — published in the American Heart Association journal Circulation — also found that heart bypass surgery patients appear to be more resistant to the negative effects of not taking prescribed medications than those who undergo percutaneous coronary interventions, also known as PCI or stenting.

Coronary artery bypass surgery redirects blood flow to the heart around clogged heart arteries. During PCI, doctors reopen blocked arteries by threading a catheter through the femoral artery in the groin or the radial artery in the wrist.

For the study, researchers collected data of 973 heart bypass patients and 2,255 stent patients who had procedures Feb. 1, 2004-July 31, 2004. They followed up after 12-18 months and in 2009 to monitor adherence to prescribed medication and report circulatory difficulties, including fatal and nonfatal heart attacks, or repeated bypass or angioplasty procedures.

Optimal medical therapy included blood thinners (aspirin or one year of double antiplatelet therapy for stent patients), statins to lower cholesterol and beta blockers for heart surgery patients. Blood thinners and statins appeared to have a profound impact on event-free, long-term survival of heart patients.

Researchers also found:

  • Bypass patients who weren’t adhering to medication therapy were 68 percent more likely to survive free from complications than non-compliant PCI patients.
  • There may not be a clinical benefit for bypass over PCI among patients adhering to recommended medication therapy.
  • Heart bypass and stent patients who left the hospital on aspirin and statins and were still on both medications at all follow-up checkups enjoyed better event-free survival rates than patients who at any point were not on their medication.

“Adherence can have a dramatic impact on the long-term outcome of both heart bypass and angioplasty patients, and that impact may be more compelling in angioplasty than in bypass patients,” said Paul Kurlansky, M.D., study lead author and assistant professor of surgery at Columbia University Medical Center and cardiac surgeon at New York-Presbyterian/Columbia University Medical Center in New York City.

Because heart bypass helps restore blood flow to the heart while stenting focuses on clearing blocked vessels, the benefits of heart bypass may rely less on appropriate medication therapy, researchers said.

“We know enough from this study to seriously ask the question: Are patients unwilling to adhere to medication schedules better off choosing heart bypass over angioplasty?” Kurlansky said. “But the answer needs to come from larger, more contemporary trials.”