Short-term ingestion of high-dose caffeine does not induce irregular heartbeats in patients with systolic heart failure, according to a study published in JAMA Internal Medicine.

Priccila Zuchinali, ScD, from the Federal University of Rio Grande do Sul in Porto Alegre, Brazil, and colleagues conducted a double-blinded clinical trial designed to evaluate real-life doses of caffeine intake. The study was performed from March 5, 2013, to October 2, 2015. The researchers examined 51 patients with predominantly moderate-to-severe left ventricular systolic dysfunction; 74% were male, and the median age was 60.6 years.

After abstaining from food and beverages containing caffeine for a 7-day washout period, the participants ingested 5 doses of 100 mL of decaffeinated coffee mixed with 100 mg of caffeine powder. Doses were consumed at 1-hour intervals for 5 hours. A treadmill test was conducted to determine if the caffeine intake influenced exercise levels.

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The primary outcome was the number and percentage of ventricular premature beats (VPBs) and supraventricular premature beats (SVPBs) measured by continuous ECG monitoring during each phase. Overall, there were no significant increases in VPBs or SVPBs in patients with higher blood levels of caffeine compared with lower levels. During the treadmill test, there were also no differences in VPBs or SVPBs.

“After 500 mg of caffeine administered over a 5-hour period, we found no association between caffeine ingestion and arrhythmic episodes, even during the physical stress of a treadmill test,” the researchers wrote. “Our results challenge the intuitive notion that caffeine intake should be limited or prohibited in patients with heart disease and at risk for arrhythmia.”


  1. Zuchinali P, Souza GC, Pimentel M, et al. Short-term effects of high-dose caffeine on cardiac arrhythmias in patients with heart failure: a randomized clinical trial. JAMA. 17 October 2016. doi:10.1001/jamainternmed.2016.6374