No significant correlation between any daily level of coffee intake and risk of either death from or hospitalization for heart failure was observed in more than 30 000 men in Sweden prospectively followed for nine years.

The finding in a somewhat rarefied population–no women, geographically restricted, and probably with limited ethnic diversity–nonetheless conflicts with an analysis of a similar but smaller group in which the risk of heart-failure hospitalization went up significantly for those drinking >5 cups of coffee per day, compared with lesser amounts, according to the authors of the new report, led by Dr Hanna N Ahmed (University of Wisconsin, Madison).

As the groups notes in the October 2009 American Heart Journal, the older finding made its way into a recent American Heart Association scientific statement, which characterizes coffee consumption as a possible minor risk factor for heart failure.

Actually, few published studies have focused on coffee consumption and clinical heart-failure end points. There have been many looking for an effect on other cardiovascular diseases or diabetes.

“The original studies looking at coffee and cardiovascular events were primarily retrospective,” coauthor Dr Emily B Levitan (Beth Israel Deaconess Medical Center, Boston, MA) told heartwire . “They tended to show that coffee was associated with an increased risk for cardiovascular disease, and I think that made a big impression on popular culture. People thought that coffee was bad for the heart.”

But her group’s study is more in line with newer retrospective and other prospective studies, which “have not really shown a major increase in risk of cardiovascular diseases,” she said. “Telling people to reduce their coffee consumption or give it up to prevent heart failure is really premature. I don’t think the evidence supports coffee as a risk factor for heart failure.”

In the current study, 37 315 members of the Cohort of Swedish Men, which included men aged 45 to 79 in two counties in Sweden, were prospectively followed for nine years. Excluded from the analysis were men with a history of cancer, diabetes, MI, or heart failure at baseline.

About 2.1% of the group experienced heart-failure hospitalization or death over the follow-up. The relative risk (RR) was 0.99 (95% CI 0.82–1.18) among those who reported drinking >5 cups of coffee per day compared with <5 cups per day in multivariate analysis. Nor did lower rates of coffee consumption significantly increase risk. (The investigators didn’t control for hypertension, itself a risk factor for heart failure, to avoid possible underestimates of risk; coffee is known to increase blood pressure.)

No significant effect of coffee intake on risk was seen among the almost 5000 other men from the Swedish cohort who had a baseline history of either diabetes or MI.

The findings should be interpreted with a few things in mind regarding coffee in Sweden, according to Levitan. She said that most of the coffee consumed there these days is filtered, as it is in many other countries, but a minority of people, often older and living in rural areas, drink boiled coffee. With that more traditional method of preparation, which is probably rare in North America, coffee has higher levels of fatty acids that could have an effect on risk.

Also, she said, “In Sweden, decaffeinated coffee is almost unheard of.” The current analysis, therefore, can’t address whether there are differences in risk based on caffeine consumption. And the questionnaires used in the study, the group writes, “did not differentiate between caffeinated and uncaffeinated sodas, so we were unable to measure total caffeine intake.”

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