Caffeine OK in heart failure patients at risk for arrhythmia

By Megan Brooks

NEW YORK (Reuters Health) - Most patients with heart failure can drink moderate amounts of caffeine with no major risk of inducing arrhythmias, a new study indicates.

"There is no contemporary data demonstrating that is safe to drink caffeine-rich beverages in patients with heart disease, regarding the risk of cardiac arrhythmias. Our results indicate the short-term use of caffeine in these patients is not pro-arrhythmic," Dr. Luis Rohde, of the Federal University of Rio Grande do Sul, Porto Alegre, Brazil, told Reuters Health by email.

"Caffeine-rich beverages have been implicated as a common cause of several cardiac-related symptoms, such as palpitations, tachycardia, or irregular heartbeats. Because of this 'intuitive' assumption, counseling to reduce or avoid caffeine consumption is still widely recommended in clinical practice by most physicians for patients with any heart disease," Dr. Rohde explained.

To see whether that advice is really appropriate, researchers studied 51 adults (mean age, 61) who were recently hospitalized for heart failure with reduced left ventricular ejection fraction.

Participants received decaffeinated coffee plus either caffeine powder or placebo lactose powder. The caffeine or placebo was ingested at one-hour intervals for a total of 500 mg of caffeine or placebo during a five-hour period. The study used a randomized placebo-controlled double-blind crossover design and included a treadmill test one hour after the last ingestion.

The primary outcome was number and percentage of ventricular and supraventricular premature beats measured by continuous electrocardiographic monitoring during the study.

"We found no association between caffeine ingestion and arrhythmic episodes," Dr. Rohde told Reuters Health, even during the physical stress of a treadmill test.

"In fact, we did not observe any indication of a potential increased risk of ventricular or supraventricular premature beats, couplets, or nonsustained tachycardia," the authors report online October 17th in JAMA Internal Medicine.

"Our results challenge the intuitive notion that caffeine intake should be limited or prohibited in patients with heart disease and at risk for arrhythmia," they say.

The researchers note that roughly half of participants in the study were habitual coffee drinkers and this could influence the results, because regular coffee drinkers might be less prone to the modulatory effects of caffeine. "Although we believe this to be unlikely, we cannot ensure that long-term and high-dose use of caffeine is not associated with a proarrhythmic effect in patients with HF," they write. "In this sense, our findings should be interpreted with caution because of the small number of patients included and the relatively low prevalence of arrhythmias that was observed." Also the results only apply to acute (one-day) use of caffeine on arrhythmias.

"This rigorous randomized clinical trial is a welcome addition to the literature," write the co-authors of a linked editorial. "However, there are limitations to the study, mainly around the short-term nature of the exposure and the small number of patients, that preclude any reliable information on clinical outcomes. For example, the upper bound of the 95% confidence interval for zero episodes of sustained and/or life-threatening arrhythmias out of 25 patients is approximately 12%, which is hardly comforting," write Dr. Jacob Kelly and Dr. Christopher Granger of the Duke Clinical Research Institute in Durham, North Carolina.

Nonetheless, the findings are "reassuring, including in the context of epidemiologic data that suggests safety in broader populations. However, the longer-term safety of moderate- and high-dose consumption of caffeine, including in popular energy drinks and in patients at high risk for arrhythmias, remains unknown. For the time being, it seems reasonable to reassure our patients that modest caffeine consumption appears to be safe, including for most patients with heart failure," they conclude.

SOURCE: http://bit.ly/2ebj79x and http://bit.ly/2eykgcH

JAMA Intern Med 2016.

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