Heart failure patients who generally managed their disease well were still more likely to end up in the hospital days after high pollution levels, according to a joint study by Intermountain Medical Center and Brigham Young University.

The research is being presented today by Benjamin Horne, Ph.D., director of cardiovascular and genetic epidemiology at IMC, to the American Heart Association's scientific sessions in New Orleans. It follows on an early study by the same researchers showing small-particulate pollution increases the risk of heart attacks.

Increasingly, cardiologists can help patients survive heart attacks, but many of them then live with after-effects, including heart failure. Since it's known that short-term, heavy pollution can increase the risk of heart attacks, the researchers wondered if exposure over a longer term to air pollution would increase the impact on heart failure patients during and shortly after exposure.

They looked at the impact of fine particulate air pollution (PM2.5) on heart failure hospitalizations in 2,628 Utah patients. With heart attacks, says co-investigator C. Arden Pope, a professor of economics at BYU who is a noted expert on health effects of pollution, they saw the pollution effects within a few days of exposure, then they went away quite quickly. With heart failure, they studied cumulative effects of two and three weeks of exposure, since heart failure is not acute, but a chronic condition marked by weakened heart muscle.

They found a 14-day lagged cumulative average of PM2.5 pollution was associated with a 13.1 percent increase in heart failure admissions. The number went up among elderly patients who had been previously hospitalized for heart failure and were only back in the hospital for a short time; their 14-day lagged PM2.5 was linked to a 32.4 percent increase in heart failure admissions. Lagged average exposure after 21 days was linked to an increased risk of 14.5 percent, according to the study abstract.

The study suggests that air pollution may play a "small, but important role in precipitating acute cardiac decompensation" in patients who otherwise have pretty good control of their heart failure, Horne says.

While the research doesn't say definitely why pollution over time increases hospitalizations, he notes several possibilities. Heart arrhythmias can influence heart failure and it's believed that pollution makes heart rhythm disorders worse. About half of heart failure resulted from heart attack, and higher levels of inflammation are associated with increased risk of heart attack. Plus, pollution increases inflammation. Or those factors could all combine. It's also possible that higher levels of pollution decrease heart rate variability — the difference between how fast the heart beats when exercising and at rest — which is already a problem for people with heart failure. If the rate never goes down, the heart is overworked.

The good news in the study, Horne said, is that people are working hard to reduce air pollution and improve the air quality. "As we get a handle on that, we can potentially reduce the risk." And in most cases, researchers believe at least some of the damage can be reversed, he says.

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