This comes from a longitudinal study that corroborates some differences between the races long observed in cross-sectional analyses.

It also pins down a specific degree of heart failure risk in African Americans in an age group not usually included in clinical trials, as well as risk factors that would be appropriate targets for preventive therapies, according to the authors, led by Dr Kirsten Bibbins-Domingo (University of California, San Francisco).

Their findings are from the Coronary Artery Risk Development in Young Adults (CARDIA) study, which followed 5,115 black and white men and women in four US cities for 20 years; they were age 18 to 30 when they entered the study. The analysis is published in the March 19, 2009 New England Journal of Medicine.

Twenty-seven participants were hospitalized for heart failure after a mean of 15 years from baseline; 26 of them, averaging 39 years in age, were black.

Other research has demonstrated that African Americans are more prone to heart failure than whites. But the current study, she said, is the first to specify what the rate of heart failure may be in blacks and how much more common it is for blacks than for whites in a young and middle-aged adult population. The 1% rate in blacks was 20 times the rate for whites of the same age group.

The study also suggests, she said, "That the precursors of heart failure are present when these individuals are in their 20s. Elevated blood pressure and higher body-mass index at baseline were strongly associated with developing heart failure two decades later, when they were in their 40s." And unfortunately, Bibbins-Domingo observed, "It's clear that young adults are the adult group least likely to know they have hypertension, if they have it, and the least likely to be treated for it or, if on treatment, to have their blood pressure controlled."

Drazner, a lead investigator with the Dallas Heart Study but not a CARDIA coauthor, pointed out that the study's African Americans and whites had similar blood pressures at baseline, but already obesity appeared to be a bit more common in African Americans, suggesting that, "Obesity may be one of the earliest players, if not the earliest, here." Although the study doesn't address the role of preventive therapy, "It does suggest that if we attack those risk factors, we might be able to mitigate these early cases of heart failure."

In multivariate analysis, four baseline features were independently significant risk factors for heart failure. Several more were observed at the echocardiographic evaluations performed at five years.

Independent Predictors of Heart-Failure Hospitalization Over 20 Years in CARDIA

Drazner observed that in an analysis of 1,335 blacks and 858 whites from the population-based Dallas Heart Study [3], which entered participants aged 30 to 67 years, LV hypertrophy was two to three times as common in blacks as in whites. That difference, as covered by heartwire when the study was published, applied to both women and men.

"So there's no question that hypertensive heart disease is an epidemic in the African American community, and we need to be aggressive at treating this disease." He noted, however, that some doctors remain hesitant to treat hypertension aggressively in younger patients.

He pointed to the Bibbins-Domingo et al conclusion that, according to their data, "The number of young, black patients with hypertension that would need to be treated to prevent one case of heart failure before 50 years of age could be as low as 21."

"I'm impressed with that," Drazner said, speculating that the relatively low number might encourage doctors to treat a greater number of younger patients with hypertension.

Bibbins-Domingo noted that at baseline in the study, blacks and whites had "remarkably similar" blood-pressure levels and were comparable in body-mass index. "So why does only one group go on to develop heart failure and not the other?" she asked.

"We know from other research that blacks have greater rises in blood pressure and body-mass index during their 20s . . . and that very likely contributes to this story. But there may very possibly be other factors, including socioeconomic factors, including genetic factors, including environmental factors, that also may play a role in why we see this predominantly in blacks but not whites at these younger ages."

• Bibbins-Domingo K, Pletcher MJ, Lin F, et al. Racial differences in incident heart failure among young adults. N Engl J Med 2009; 360:1179-1190.
• Peterson ED, Yancy CW. Eliminating racial and ethnic disparities in cardiac care. N Engl J Med 2009; 360:1172-1174.