More good news for coffee drinkers. I can remember spending time explaining why my patient in the hospital after a heart attack could not have their morning coffee, because it might cause a life threatening arrythmia. It looks like I wasted my breath and deprived them needlessly. A recent study reported on MedPage Today shows moderate coffee intake is not only not associated with more arrhythmias, but coffee drinkers may actually have less serious cardiac arrhythmias. Coffee Not Linked to Serious Arrhythmias
By Todd Neale, Staff Writer, MedPage Today
Published: March 02, 2010
Reviewed by Robert Jasmer, MD; Associate Clinical Professor of Medicine, University of California, San Francisco.
SAN FRANCISCO — Contrary to conventional thinking, drinking lots of coffee appears to be associated with a lower risk of hospitalization for an arrhythmia, researchers found.
In a long-term prospective study, patients who reported drinking at least four cups of coffee a day were 18% less likely to be admitted with a heart rhythm disturbance than those who drank no coffee at all (RR 0.82, 95% CI 0.70 to 0.90), according to Arthur Klatsky, MD, a senior consultant in cardiology at Kaiser Permanente Division of Research in Oakland, Calif. Tea consumption did not have a similar effect.
The findings, which were presented at the American Heart Association’s Conference on Cardiovascular Disease Epidemiology and Prevention here, were unexpected, Klatsky said, because patient reports of palpitation or forceful heartbeat after drinking coffee are not uncommon.
“I think the take-home message from this very important epidemiologic study is that most people can drink coffee, even several cups of coffee, without increasing their risk of having a significant heart rhythm disturbance that would require hospitalization,” said Ellenbogen, an AHA spokesman.
Although conventional wisdom dictates that coffee can increase the risk of arrhythmia, few studies have explored the relationship, according to Klatsky.
So he and his colleagues analyzed data on 130,054 men and women who were treated at Kaiser. As part of a baseline medical check-up between 1978 and 1985, all participants completed a questionnaire that included information on coffee, alcohol, and tea consumption. Most were not asked to differentiate between caffeinated and decaffeinated coffee.
Through follow-up, 2.6% were hospitalized for an arrhythmia; half had atrial fibrillation.
When coffee drinking was evaluated as a continuous variable, increasing consumption was associated with decreasing risk of hospitalization (P<0.001).
The findings were consistent across types of rhythm disturbance and patient subgroups. In particular, patients with cardiorespiratory symptoms, or a history of such symptoms, at baseline had a similarly reduced risk.
Controlling for smoking, age, sex, ethnicity, alcohol, body mass index, and education did not substantially affect the findings.
In the small subset of 11,656 patients who provided specific information on their coffee consumption, it appeared the risk reduction was primarily attributed to caffeine, Klatsky said, although the small numbers precluded drawing firm conclusions.
The observational study could not establish a causal relationship, but Klatsky said it was plausible that caffeine could protect against arrhythmias by blocking the action of adenosine.
Adenosine is a nucleoside that causes drowsiness and sleepiness in the brain, and caffeine counteracts its effects by attaching to its receptors.
The chemical also has actions in the heart, affecting the conduction system, endothelial function, and recovery time of the cardiomyocytes. Caffeine’s antagonistic effect on adenosine could affect the development of arrhythmias, although this is speculative, Klatsky said.
“I do think this [study] is going to surprise people,” he said. “I think conventional wisdom is that coffee can cause palpitations and it can cause rhythm problems. I think, though, that conventional wisdom is not always right, and the data that were available before this study really do not support the idea that moderate amounts of coffee provoke rhythm problems.”
The study was supported by a grant from the Kaiser Foundation Research Institute and the Robert Wood Johnson Foundation.
The authors did not make any financial disclosures.
Primary source: American Heart Association’s Conference on Cardiovascular Disease Epidemiology and PreventionSource reference:
Hasan A, et al “Coffee, caffeine, and risk of hospitalization for arrhythmias” CCDEP 2010; Abstract P461.
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