Despite proven survival benefits, roughly two-thirds of heart attack patients forego cardiac rehabilitation, according to a report from the Centers for Disease Control and Prevention (CDC).

Each year, approximately 790,000 adults in the U.S. suffer MI, including 210,000 that are recurrent heart attacks. A previous review has shown that after a heart attack, patients using cardiac rehab are 57 percent less likely to experience cardiac-related mortality than those not attending rehab.

But an analysis of telephone survey reports from 2013 and 2015 showed that only about one-third of patients are utilizing rehab, which includes exercise counseling and training, heart-health education and counseling to reduce stress. In 2013 surveys, 33.7 percent of adults who had a heart attack reported the subsequent use of the outpatient therapy. In 2015, the percentage increased marginally to 35.5.

“These estimates highlight missed opportunities to access an evidenced-based intervention that has been documented to improve patient survival, quality of life, functional status, and cardiovascular risk profile following a significant health event, as well as reduce risk for a recurrent heart attack and psychological disorders,” wrote corresponding author Jim Fang, MD, of the National Center for Chronic Disease Prevention and Health Promotion.

The CDC drew survey data from 20 states and the District of Columbia for 2013. Reporting from four states was included in the 2015 analysis.

With a small sampling of states, Fang and colleagues noted, the data may not be nationally representative. The survey responses were also subject to recall bias, which may have led to an underestimation of either heart attack or use of rehab. In addition, the survey didn’t account for respondents’ reasoning for skipping cardiac rehab, or whether they had attended the recommended number of rehab sessions.

Despite those limitations, the findings were robust enough for Fang and colleagues to conclude cardiac rehab programs are being vastly underutilized—especially by younger people, women, minorities and those with less than a college education.

“Some strategies that might improve use of cardiac rehab include higher payment for rehab by insurers, eliminating or reducing copays for patients, extending cardiac rehab clinic hours to improve access, as well as providing standardized referrals coupled with linkage to cardiac rehab staff member liaisons at hospital discharge or by primary care providers and cardiologists,” Fang and colleagues wrote. “In addition, patients who have experienced a heart attack should be made aware of the availability of alternative models of cardiac rehab, such as telehealth and home-based rehab, to reduce the barriers related to transportation and responsibilities at home or work.”