A skinny frame may make it harder to survive a heart attack, suggests a new study published Tuesday in PLOS-Medicine.

The researchers analyzed data from the Cooperative Cardiovascular Project, which kept track of older adults on Medicare who had been hospitalized for a heart attack for an average of 17 years after their release. From 1994 to 1996, that included 57,574 adults, 9.8 percent of whom were underweight, and the rest of whom were normal weight. Whether it was 30 days or 17 years after the initial heart attack, underweight people were more likely to die, having a 61 to 73 percent greater risk of death than their stockier counterparts.

“The survival curves for underweight and normal weight patients diverged early and remained separate over all 17 years of follow-up, suggesting that underweight patients accrued a survival disadvantage over time,” the researchers wrote.

Though having a low Body Mass Index (BMI) of under 18.5 has long been linked to poor health outcomes, including heart attack survival, the researchers wanted to tease out other possible reasons for the link. For instance, severe chronic illness often causes a gradual wasting away of the body known as cachexia; and unintentional weight loss is one of the main symptoms of frailty.

But while underweight people were certainly more likely to have other health conditions and be more frail, a small but increased mortality risk still existed after these factors were taken into account. The same was true when looking at people who had no underlying health conditions, though only over the long term. That indicates that being underweight carries its own unique dangers following a heart attack.

Just as importantly, it also means there could be specific steps doctors can take to help mitigate that added risk.

“Clinically, our findings imply that underweight patients may benefit from treatment strategies that focus on promoting nutritional status and weight gain, regardless of the reason for their low BMI,” the authors wrote. That could include anything from providing patients high-calorie supplements à la Ensure while in the hospital to prescribing nutritionist-led consultations or medications once they return home. And indeed, the authors cite research showing that patients with cachexia as a result of cancer or cardiac disease have had improved survival rates following weight gain therapy.

Finding out whether the same holds true for underweight heart attack patients, with or without cachexia, however, will require dedicated trials, the authors cautioned.

Source: Bucholz E, Krumholz H, Krumholz H, et al. Underweight, Markers of Cachexia, and Mortality in Acute Myocardial Infarction: A Prospective Cohort Study of Elderly Medicare Beneficiaries. PLOS Medicine. 2016.