A study, led by experts from Cardiology and Cardiovascular Sciences, Medical School, Federal University of Rio Grande do Sul, Porto Alerge, Brazil, brings a good news for people who suffer from chronic systolic heart failure (HF) but are addicted to consuming high amounts of caffeine, simultaneously.
Published recently on 17th October in the Journal of American Medical Association (JAMA), Internal Medicine, this small randomized trial suggests that ingesting high doses of caffeine is safe for people who suffer from systolic heart failure and those who are at high risk of ventricular arrhythmia (irregular heartbeat), as it was not found to be associated with inducing arrhythmias.
Consuming high caffeine containing beverages and foods is long associated with increasing heart health risks, particularly for the people who have had experienced heart failure in the past. While many of these claims remain mere speculations with little or no supportive evidence present, many people who fear for their health often believe this speculation to be true.
As a result, these people often tend to forgo their fondness with caffeinated beverages, specially tea and coffee in a hope to receive better health benefits.
Igniting the caffeine controversy, the researchers went out to compare the effects of high-dose caffeine with placebo on the frequency of supraventricular (rapid heartbeat caused by electrical impulses originating from areas above ventricles, which are the lower chambers of heart) and ventricular (irregular beating of ventricles) arrhythmias.
During this double-blinded randomized trial, carried out at the Heart Failure and Cardiac Transplant Clinic of a tertiary care university hospital, the heart activity after ingesting high dose caffeine was observed both at rest and during a symptom-limited exercise test, the treadmill exercise.
The study recruited 51 participants who had experienced a chronic heart failure, having a moderate-to-severe systolic dysfunction, which is characterized by reduced myocardial contractility (reduced ability of the cardiac muscles to contract).
As a result of this reduced myocardial contractility, a reduction in the left ventricular ejection fraction (LVEF) is also recorded which is a measure of percentage of blood volume pumped out of the heart, each time it contracts. Moderate to severe systolic function translates into the LVEF <45% which was present in this study participants.
These participants were given caffeine or lactose capsules of 100 mg along with 5 doses of 100mL decaffeinated coffee at an interval of 1 hour. 100mL of decaffeinated coffee was given for 5 hours, cumulatively making it 500mL.
The control group was, on the other hand, given a similar volume of placebo. This protocol was repeated after 1-week washout period and the study continued from March 2013 to October 2015.
The average left ventricular ejection fraction of the 51 participants was 29%. Out of them, 31 people had a pacemaker device implant. Most of these patients were also receiving standard heart failure treatment, which included beta blockers in 98%,, and ACE inhibitor or angiotensin II receptor blocker (ARB) in 97%.
By the end of this study, it was observed that the difference in the ventricular premature beats between the caffeine group and placebo group was not significant, which was recorded as 185 and 239 beats, respectively. The supraventricular premature beats were recorded as 6 and 6 beats, respectively.
When similar continuous electrocardiographic monitoring was carried out during exercise, both ventricular and supraventricular premature beats, peak oxygen consumption, heart rate and duration of exercise remained unaffected by caffeine intake.
In addition to this, ventricular premature beats in patients with high plasma caffeine concentration levels in comparison with low plasma caffeine concentration levels in placebo group had no significant difference which was recorded at 91, 223, and 207 beats, respectively.
Although it is a small study, the findings are significant and the extensively carried out procedure speaks for its credibility.
The stance of American Heart Association, though, is worth noting at this point. It says that studies linking negative effects of caffeine on heart health are currently conflicting and hence not conclusive.
We know that caffeine has a role in stimulating central nervous system and helps us staying alert. It releases free fatty acids from adipose tissues and it can lead to dehydration due to increased urination. But nothing can be certainly said for heart, as of now.
The AHA also adds that moderate amounts of caffeine, up to 2 cups of coffee per day, are not harmful for health (one cup of brewed coffee can contain 95-200 mg of caffeine).
With this study, many firmly held notions against caffeine consumption are challenged and the landscape of medical debate involving caffeine intake has taken an interesting turn.
While many people who stand in opposition of caffeine intake will now be triggered to bring forward some evidence to refute the findings of this very study, you can enjoy a cup of coffee in the meanwhile without worrying much about your heart health