Air Pollution Takes Greater Toll on the Hearts of Black Americans Than Whites

by Steven Reinberg

A new study reports that air pollution takes a greater toll on the hearts of black Americans than whites, in part because they often live in poorer areas with more pollution.

"The greater risk of death from heart disease among blacks, compared with whites, is partially explained by higher exposure to air pollution," said lead researcher Dr. Sebhat Erqou, a fellow in cardiovascular disease at the University of Pittsburgh.

The western Pennsylvania study looked at the relationship between heart disease and a component of air pollution known as fine particulate matter. Fine particulate matter (called PM2.5, which is about 40 times smaller than the width of a human hair) stems from factories, vehicles, power plants, fires and secondhand smoke.

Researchers found that blacks living in areas where this type of pollution is high have a 45 percent higher risk of heart disease and death from any cause than whites, even after taking into account other common risk factors.

But about one-quarter of that elevated risk was attributed to their greater exposure to dirty air, which correlated with poverty, Erqou said.

Blacks and other minorities more often live close to sources of environmental pollution, such as highways, the researchers said in background notes. As income and education increased, the impact of air pollution decreased, Erqou said.

Chronic exposure to air pollution has been associated with numerous ill effects, included elevated blood sugar, poorly functioning blood vessels, heart disease and death, he noted.

This study reflects, again, racial disparities that exist in medical outcomes, said Dr. Rachel Bond, associate director for women's heart health at Lenox Hill Hospital in New York City.

"Air pollution clearly has a detrimental effect on the black community disproportionate to the white community with respect to cardiac disease outcomes," said Bond, who was not part of the study.

Another New York specialist who was not involved with the research pointed to the broad role economic differences can play.

"Exposure to air pollution may be more of a factor of socioeconomic status than race itself, and there may be confounders such as smoking history, home environment and occupation, which can affect health," said Dr. Walter Chua. He's a senior pulmonary attending physician at Long Island Jewish Forest Hills.

For the study, Erqou and colleagues reviewed data on PM2.5 and black carbon, which is an ultrafine component of PM2.5, from a Pittsburgh-area air monitoring campaign.

The researchers combined that with information from an ongoing heart study involving more than 1,700 residents (average age 59) of western Pennsylvania.

Each year, participants complete questionnaires that ask about heart-related hospitalizations, heart attacks, acute coronary syndrome, stroke, angioplasty or death from heart disease.

Erqou's team found that greater PM2.5 exposure was associated with increased blood sugar, worse blood vessel function, and higher odds for problems such as heart attack and stroke, and death from all causes.

The investigators also found that compared with whites, blacks had significantly higher average exposures to PM2.5 and black carbon.

A weakness of the study is that it's limited to one city, so the findings might be different in other locales, Erqou said. Also, the study only found an association rather than a cause-and-effect link.

Chua said it would be interesting to look at other major cities, including New York and San Francisco, to see if these disparities still exist, given that those cities are more diverse, he said.

Meanwhile, "the push to maintain good air quality should still continue," Chua said.

Cigarette Smoking Raises Heart Failure Risk in African-Americans

by Anne Harding

Cigarette smoking sharply increases the risk of heart failure in black men and women in the U.S., according to a new study by senior author, Dr. Michael E. Hall, an associate professor of medicine at the University of Mississippi Medical Center in Jackson.

“These findings suggest if you have heart failure or you have risk factors for heart failure such as early markers for heart damage like a thicker heart or a weak heart, you should specifically be targeted for smoking cessation strategies,” said the study’s senior author Dr. Hall.

In heart failure, the muscles of the heart weaken and enlarge so the organ can no longer pump blood efficiently, leading to shortness of breath and water retention. Heart failure is most often the result of damage from coronary artery disease, a buildup of fatty material within the heart arteries associated with heart attack and stroke. High blood pressure, excess weight, infection and several other factors can also contribute to heart failure.

Cigarette smoking is clearly associated with coronary artery disease, but its relationship with heart failure is not as well known, especially among African Americans, Hall’s team writes in the journal Circulation.

Blacks in the U.S. have double the incidence of heart failure as other groups, the researchers note. While smoking in this community has declined, it is still at 18 percent of adults, they add.

To investigate the potential role of smoking in heart failure risk, the researchers analyzed data on 4,129 black adults in Mississippi who participated in the Jackson Heart Study. Their average age was 54, and all were free of heart disease when they enrolled. Twelve percent reported being smokers, 18 percent were ex-smokers and 70 percent had never smoked.

Compared to never-smokers, the smokers had more enlargement of the left ventricle, the heart’s main pumping chamber, and worse left ventricular function. Levels of a hormone released by the heart that indicates heart failure, called brain natriuretic peptide (BNP), were higher in smokers than never-smokers, and those levels increased with the intensity and duration of smoking.

Once the authors took factors associated with both smoking and heart failure, such as coronary artery disease, into account, they found that smokers were almost three times more likely than non-smokers to be hospitalized for heart failure during eight years of follow-up.

People who smoked at least 20 cigarettes a day saw their risk increase about 3.5-fold. Those who had smoked the equivalent of a pack or more a day for 15 or more years were twice as likely as never-smokers to be hospitalized for heart failure.

Physicians will typically ask patients with coronary artery disease about smoking, and urge them to quit if they do, Hall said in a telephone interview. But heart failure seems to be a less obvious cue to many doctors.

“We probably in the health community need to do a better job of recommending cessation strategies for people who have risk factors for heart failure,” Hall said. “If they have risk factors, they should be strongly counseled to quit, that should be a no-brainer.”

He acknowledged that lack of health insurance and other factors can be barriers to effective smoking cessation treatment. But the costs of drugs proven to help people quit have declined, Hall noted, and many are now available for less than a pack-a-day smoker spends in a month on cigarettes.

In future research, he and his colleagues plan to examine whether newer nicotine delivery devices, like e-cigarettes, have similar effects on the heart.