Lots of caffeine may be OK for those with systolic heart failure

Patients with heart failure may not have to limit their caffeine intake, according to a recent small, randomized study.

The trial enrolled 51 patients in Brazil who had systolic heart failure and were at high risk for ventricular arrhythmias. A group that consumed 500 mg of caffeine within a five-hour period had a similar number of arrhythmic episodes at rest and during a treadmill test compared with a placebo group.

Lead researcher Priccila Zuchinali, ScD, of Federal University of Rio Grande do Sul in Porto Alegre, Brazil, and colleagues published their results online Oct. 17 in JAMA Internal Medicine.

“We did not observe any indication of a potential increased risk of ventricular or supraventricular premature beats, couplets, or nonsustained tachycardia,” they 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.”

The researchers conducted the study from March 5, 2013 to Oct. 2, 2015 and recruited patients from a tertiary-care hospital in Porto Alegre who had a previous diagnosis of heart failure, left ventricular ejection fraction less than 45 percent and New York Heart Association functional class I to III heart failure.

The mean age of patients was 60.6 years old, and 74 percent were male. The first 25 patients were required to have an implantable cardioverter-defibrillator (ICD), but the researchers then amended the protocol to include patients who did not have an ICD.

After a seven-day washout period, during which patients were told not to consume food and beverage sources of caffeine, the researchers randomized the patients to the caffeine or placebo groups. Patients ingested five doses of 100 mL of decaffeinated coffee mixed with 100 mg of caffeine or lactose powder at one-hour intervals. They arrived at 8 a.m. and drank their first dose of caffeine at 9 a.m., which was when they began continuous electrocardiogram (ECG) monitoring. They consumed their last dose of caffeine at 1 p.m. and then had a treadmill test at approximately 2 p.m.

There were no significant differences between the groups in the number of ventricular and supraventricular premature beats, couplets, bigeminal cycles or nonsustained tachycardia during continuous ECG monitoring. They also had similar mean heart rates.

The researchers mentioned that caffeine consumption did not influence the duration of exercise, ventricular and supraventricular premature beats, estimated peak oxygen consumption and heart rate.

They also cited a few limitations of the study, including that approximately half of the patients were habitual coffee drinkers. They noted that the study had a small number of patients and a relatively low prevalence of arrhythmias. In addition, the sub-group analyses were underpowered for definitive conclusions.

“The acute ingestion of high doses of caffeine did not induce arrhythmias in patients with chronic systolic [heart failure] at rest and during a symptom-limited physical exercise,” the researchers wrote. “To date, there is no solid evidence to support the common recommendation to limit moderate caffeine consumption in patients at risk for arrhythmias.”