Researchers evaluated data on more than 132,000 white heart attack patients and almost 9,000 black patients covered by Medicare, the government health program for the elderly and disabled. They used postal codes to assess income levels in patients' communities.
After 17 years of follow-up, the overall survival rate was 7.4 percent for white patients and 5.7 percent for black patients, according to the results published in Circulation, the journal of the American Heart Association.
On average, across all ages, white patients in low-income areas lived longer after a heart attack - about 5.6 years compared with 5.4 years for black patients. But in high-income communities, the gap widened to a life expectancy of seven years for white people and 6.3 years for black individuals.
"We found that socioeconomic status did not explain the racial disparities in life expectancy after a heart attack," lead study author Dr. Emily Bucholz of Boston Children's Hospital said by email.
"Contrary to common belief, this suggests that improving socioeconomic standing may improve outcomes for black and white patients globally but is unlikely to eliminate racial disparities in health," Bucholz added.
To see how race and class impact heart attack outcomes, Bucholz and colleagues reviewed health records collected from 1994 to 1996 for patients aged 65 to 90 years.
Just 6.3 percent of the patients were black, and only 6.8 percent lived in low-income communities, based on the typical household income in their postal codes.
Among white patients under 80, life expectancy was longest for patients in the most affluent neighborhoods and it got progressively shorter for middle-income and poor communities, the study found.
By contrast, life expectancy was similar for black patients residing in poor and middle-income communities across all ages. Only black patients under age 75 living in affluent areas had a survival advantage compared with their peers in less wealthy neighborhoods.
One shortcoming of the study is that it included a small proportion of black and poor patients, the authors acknowledge. It's also possible that using postal codes to assess income may have led to some instances where income levels were inflated or underestimated, the authors note.
It's possible that black patients living in affluent areas don't fare as well as white patients because they don't have the same amount of social support from their peers, said Dr. Joaquin Cigarroa, a cardiovascular medicine researcher at Oregon Health & Science University in Portland.
In poor neighborhoods, black patients may face additional challenges to surviving a heart attack, added Cigarroa, who wasn't involved in the study.
"They more often live in low socioeconomic segments of our community that often have less access to health care resources and less access to stores with good nutrition," Cigarroa said by email. "In addition, these segments of our community are often not ideally configured for promoting physical activity with parks, sidewalks, bike lanes, etc."
The study findings highlight a need to improve outcomes among poor and black patients and suggest some differences in heart attack survival may come down to disparities in quality of care, said senior study author Dr. Harlan Krumholz of Yale University School of Medicine in New Haven, Connecticut.
Because black patients have a greater burden of heart disease than white people, doctors may also need to focus more on prevention in this community, Krumholz said by email.
"Healthy heart habits may be even more important for African-Americans, for whom avoiding a heart attack is even more important given their worse outcomes after the event," Krumholz said.