Patients who took a high dose of omega-3 fatty acids from fish oil daily for six months after a heart attack improved their hearts’ function and reduced scarring in the undamaged muscle, according to a new study.

The heart’s shape and function can be altered after a heart attack, a condition known as post-heart attack remodeling that could lead to poor outcomes and heart failure. Therapies to heal the heart or prevent adverse remodeling remain scarce.

A previous study found that omega-3 fatty acids from fish oil were associated with improved survival for heart attack patients. But the role of omega-3 fatty acids in improving the structure and tissue of the heart in patients receiving guideline-based therapy after a heart attack was unknown.

In the new randomized clinical trial, patients taking a dose of 4 grams of omega-3 fatty acids daily for six months compared to those taking a placebo:

  • Experienced a 5.8 percent reduction in left ventricular end-systolic volume index, a clinical marker that can predict patient outcome after a heart attack.
  • Had a 5.6 percent reduction in a measurement of scarred connective tissue (fibrosis) formation in the non-damaged heart muscle.

“Heart failure is still a major problem after a heart attack despite all the therapy we have and the advances in interventional care,” said Raymond Y. Kwong, M.D., M.P.H., director of Cardiac Magnetic Resonance Imaging at Brigham and Women’s Hospital and an associate professor of medicine at Harvard Medical School in Boston, Massachusetts.

“Our findings show that omega-3 fatty acids are a safe and effective treatment in improving cardiac remodeling, so it may be promising in reducing the incidence of heart failure or death, which are still major healthcare burdens to patients who suffer a heart attack.”

The results suggest that omega-3 fatty acids allow the heart to contract better and reduces the fibrosis in the region that’s not damaged, Kwong said.

The researchers also observed a reduction in biomarkers for inflammation, suggesting that omega-3 fatty acids have some anti-inflammatory properties.

Both groups in the study received treatment based on American College of Cardiology Foundation and American Heart Association guidelines.

The study is published in the American Heart Association journal Circulation.