People with symptoms of a heart attack are less likely to visit the emergency room if they lack health insurance, studies have found.

So in 2014, when the Affordable Care Act allowed states to expand the number of residents eligible for Medicaid, that suggested a real-life experiment to a team of University of Pennsylvania researchers:

Would the increase in insurance coverage lead to a decline in deaths from heart attacks and other heart disease?

An analysis of seven years of death rates in people aged 45 to 64 suggests the answer is yes, the team reported Wednesday in the journal JAMA Cardiology.

At a glance, the decline may sound modest — 4.3 fewer deaths per 100,000 residents per year in 29 states that were the first to expand Medicaid, including Pennsylvania and New Jersey. But when that rate is multiplied by the population in those states, it translates to 2,000 fewer deaths per year, the study found.

The authors, who collaborated with researchers from Harvard Medical School, compared the heart-disease death rates in the four years before Medicaid was expanded in those states (2010 through 2013) with the death rates in the three years afterward.

Because the number of deaths from heart disease in younger adults has been on the rise nationwide, the researchers also analyzed deaths in states that did not expand Medicaid, so the broader trend could be taken into account, lead study author Sameed Khatana said.

That is, the decline of 2,000 deaths represents the projected difference between reality and what would have happened in those states had they not expanded Medicaid, said Khatana, a cardiovascular medicine fellow at Penn’s Perelman School of Medicine.

“In states that didn’t expand Medicaid, mortality kept going up,” he said. “But in states that did expand Medicaid, mortality stayed relatively stable.”

The findings come as Medicaid expansion is under fire in some states, with Republican lawmakers proposing that in order to qualify for the health insurance, people would need to prove that they are employed, among other requirements.

States expanded access to Medicaid in a variety of ways starting in 2014, generally by raising the income threshold at which people could qualify for the insurance, and also by removing other hurdles, such as requiring that the insured person have a disability.

Because the Penn study was observational, the researchers could not show that Medicaid expansion caused a decline in deaths from heart disease, only that the two trends went hand in hand.

But on a population level, it is plausible that expanding insurance coverage could prevent deaths from heart disease, Khatana said. Prompt treatment in an emergency room is essential for improving a person’s chance of surviving the kinds of cardiovascular problems included in the analysis: heart attack, stroke, and sudden cardiac arrest.

In addition to determining the statewide impact of Medicaid expansion, the study authors also drilled down to the county level, looking at the numbers of people who actually signed up for the insurance.

What they found reinforced the findings on the state level, Khatana said. Counties with the smallest increases in insurance coverage had the largest increases in deaths from cardiovascular disease, the study found.