Americans’ hearts are the healthiest they’ve been in a long time, suggests a new study published this month in JAMA.

Researchers collected data from five different population studies conducted throughout the 1980s and 1990s. The studies collectively involved more than 28,000 healthy adults from the ages 40 to 79 with no prior history of cardiovascular disease,. Half of participants were followed over the course of 12 years starting in 1983, while the other half were followed starting in 1996. From 1983 to 2011, researchers found the incidence of any coronary heart disease had declined almost 20 percent among the newer generation of adults, which included heart attacks, intense chest pain, and coronary death.

“We have made progress in reducing incidence of coronary heart disease, but continued vigilance is needed to reduce the underlying causes of heart disease,” said the study's senior author Dr. Michael J. Pencina, director of biostatistics at Duke University’s Duke Clinical Research Institute, in a statement.

Importantly, they also found a similar drop in known risk factors of heart disease, such as smoking and high blood pressure. And though the rate of type 2 diabetes has generally increased over time, its connection to heart disease has steadily gotten weaker.

“The risk of heart disease in adults with diabetes declined over time, leading to a decrease in the fraction of heart disease attributable to diabetes,” Pencina explained. “But this progress may be offset in the future if the prevalence of diabetes in the population continues to increase.”

Elsewhere, other research has shown that deaths from heart disease have also taken a sharp drop over the decades, thanks in part not only to a decline in preventable risk factors, but better treatments available as well. However, a study earlier this year found that much of this drop has been concentrated in the northernmost parts of the country.

While Pencina and his colleagues are encouraged by their findings, they note there’s still lot more work to be done in fighting heart disease. Especially since the link between the risk factors they studied - with the exception of diabetes - and heart disease remained as strong as ever over the years.

“Risk factors still matter,” Pencina said. “While the event rates went down and it appears the interventions are working, that doesn’t mean we can ignore the risk factors. There are further gains that could be made if we were to prevent these conditions.”

Heart disease in general is still the leading cause of death among all Americans, men and women alike. An estimated 600,000 die every year from it, according to the Centers for Disease Control and Prevention. And about 370,000 die specifically from coronary heart disease, which involves a blockage of the arteries that supply blood to the heart from plaque buildup.

Source: Navar A, Peterson E, Wojdyla D, et al. Temporal Changes in the Association Between Modifiable Risk Factors and Coronary Heart Disease Incidence. JAMA. 2016.