Reducing caffeine for treatment of arrhythmias - myth or evidence-based medicine?
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Introduction
Cardiac arrhythmias are frequently encountered in isolation or associated with other conditions (eg. hyperthyroidism, sepsis, myocardial infarction, cardiac surgery). The term encompasses a range of disorders from benign premature atrial or ventricular complexes to malignant tachycardias such as ventricular tachycardia or fibrillation. In clinical practice, patients with a suspected or confirmed diagnosis of cardiac arrhythmia are often advised to limit their intake of caffeine, which can be an important source of enjoyment and have significant impact on their overall quality of life. Furthermore patients are exposed to news headlines such as “Teen dies from too much caffeine, coroner says.”(1) In this review, we will explore the association between caffeine intake and arrhythmias to evaluate whether providing such advice is truly justified.
Discussion
Caffeine is a methylxanthine compound related to theophylline that is able to stimulate the sympathetic nervous system through a variety of different mechanisms. Its effects include non-selective competitive antagonism of adenosine receptors that are responsible for cardiovascular regulation and increasing cytosolic calcium concentrations by blocking reuptake of calcium into the sarcoplasmic reticulum.(2)
The caffeine content in standard beverages is summarised in Table 1.(3,4)
Drinks | Caffeine content (mg) |
---|---|
Starbucks Hot Chocolate | 25 |
Green tea | 29 |
Coca-Cola | 34 |
Black tea | 47 |
Instant coffee | 57 |
Red Bull energy drink | 76 |
Shot of espresso | 77 |
Nespresso capsule - except Kazaar | 50 - 80 |
Starbucks - Caffe Latte or Cappuccino | 150 |
Monster energy drink | 160 |
Brewed coffee | 163 |
Table 1. Caffeine content in beverages
Previous studies have demonstrated that very high doses of caffeine in animals increased susceptibility to both supraventricular and ventricular arrhythmias.(5–7)
However, the results from human trials are less convincing with many studies showing no increase in arrhythmia burden or symptoms despite high doses of caffeine.(8–16) Some of these negative studies included patients with known arrhythmias(12,14,16), reduced ejection fraction heart failure(8) and recent myocardial infarction.(17) One large epidemiological study did show increased incidence of ventricular premature beats with caffeine. However, it was performed almost 4 decades ago and the association was found only in patients who ingested very high doses of caffeine (≥9 cups of coffee per day).(18) Studies demonstrating a lower risk of arrhythmias with caffeine are sparse. A recent study of 1,475 healthy patients found a lower incidence of atrial fibrillation with caffeine intake of >320mg per day.(19) A summary of published trials can be found in Table 2.
Study | Year | n | Findings |
---|---|---|---|
No increased risk with caffeine | |||
Zuchinali et al (8) | 2016 | 51 | No increase in arrhythmias with ingestion of 500mg caffeine in patients with reduced ejection fraction heart failure |
Conen et al (9) | 2010 | 33,638 | No increased risk of AF in healthy females |
Frost et al (10) | 2005 | 47,949 | No increased risk of AF or atrial flutter in healthy patients |
Newby et al (11) | 1996 | 13 | No change in symptoms or frequency of VPB with caffeine restriction in patients with symptomatic idiopathic VPBs |
Chelsky et al (12) | 1990 | 22 | No increase in inducibility or severity of arrhythmias in patients with previous ventricular arrhythmias |
Myers et al (13) | 1990 | 35 | No increase in ventricular arrhythmias with ingestion of 450mg caffeine in recent MI patients |
Graboys et al (14) | 1989 | 50 | No increase in arrhythmias with ingestion of 200mg caffeine during stress test in patients with malignant arrhythmias |
Newcombe et al (15) | 1988 | 18 | No increase in arrhythmias with ingestion of 1mg/kg caffeine every 30 minutes during all waking hours in healthy patients |
Myers et al (17) | 1987 | 70 | No increase in frequency or severity of ventricular arrhythmias with ingestion of 300mg caffeine in recent MI patients |
DeBacker et al (20) | 1979 | 81 | No decrease in VPB frequency with abstinence from caffeine in healthy males |
Clee et al (16) | 1979 | 50 | No increase in dysarrhythmias with caffeine ingestion in elderly patients (>60 years old) with a high incidence of ectopic beats, supraventricular tachycardia and sinus arrest |
Increased risk with caffeine | |||
Sutherland et al (21) | 1985 | 18 | Increased frequency of VPB with ingestion of 1mg/kg caffeine in patients with frequent VPB at baseline |
Prineas et al (18) | 1980 | 7311 | Ingestion of ≥9 cups of coffee per day is associated with 2x the prevalence of VPBs, compared to ≤2 cups of coffee per day in healthy patients |
Lower risk with caffeine | |||
Casiglia et al (19) | 2018 | 1475 | Lower incidence of AF with higher caffeine intake (>320mg per day) in healthy patients |
Table 2. Studies evaluating the effects of caffeine on arrhythmias. AF = atrial fibrillation; VPB = ventricular premature beats; MI = myocardial infarction
The European Society of Cardiology (ESC)(22,23) and American College of Cardiology/American Heart Association/Heart Rhythm Society (ACC/AHA/HRS)(24) guidelines for supraventricular and ventricular arrhythmias do suggest that patients should be advised to avoid stimulants such as caffeine. However, this is in the context of benign arrhythmias only, with no references provided.
With conflicting results from several studies, it is not surprising that physicians may choose to remain cautious and advise at-risk patients to reduce their caffeine intake. However, as with all clinical decisions, the patient’s views should be respected and any envisaged benefits should be balanced against potential impact to their quality of life. Additionally, it should be done in light of current available evidence that do not suggest an increased risk of arrhythmias with caffeine. However, there may remain a minority of patients who exhibit a clear relationship between arrhythmia onset and burden with caffeine intake. In such patients, it would seem appropriate to avoid caffeine.
Conclusion
Overall the evidence do not suggest that reducing or avoiding caffeine intake will reduce the risk of arrhythmias.
References
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- Zuchinali P, Souza GC, Pimentel M, Chemello D, Zimerman A, Giaretta V, et al. Short-term Effects of High-Dose Caffeine on Cardiac Arrhythmias in Patients With Heart Failure: A Randomized Clinical Trial. JAMA Intern Med. 2016 Dec;176(12):1752–9.
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- Frost L, Vestergaard P. Caffeine and risk of atrial fibrillation or flutter: the Danish Diet, Cancer, and Health Study. Am J Clin Nutr. 2005 Mar;81(3):578–82.
- Newby DE, Neilson JM, Jarvie DR, Boon NA. Caffeine restriction has no role in the management of patients with symptomatic idiopathic ventricular premature beats. Heart. 1996 Oct;76(4):355–7.
- Chelsky LB, Cutler JE, Griffith K, Kron J, McClelland JH, McAnulty JH. Caffeine and ventricular arrhythmias. An electrophysiological approach. JAMA. 1990 Nov;264(17):2236–40.
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- Graboys TB, Blatt CM, Lown B. The effect of caffeine on ventricular ectopic activity in patients with malignant ventricular arrhythmia. Arch Intern Med. 1989 Mar;149(3):637–9.
- Newcombe PF, Renton KW, Rautaharju PM, Spencer CA, Montague TJ. High-dose caffeine and cardiac rate and rhythm in normal subjects. Chest. 1988 Jul;94(1):90–4.
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- Prineas RJ, Jacobs DRJ, Crow RS, Blackburn H. Coffee, tea and VPB. J Chronic Dis. 1980;33(2):67–72.
- Casiglia E, Tikhonoff V, Albertini F, Gasparotti F, Mazza A, Montagnana M, et al. Caffeine intake reduces incident atrial fibrillation at a population level. Eur J Prev Cardiol. 2018 Jul;25(10):1055–62.
- DeBacker G, Jacobs D, Prineas R, Crow R, Vilandre J, Kennedy H, et al. Ventricular premature contractions: a randomized non-drug intervention trial in normal men. Circulation. 1979 Apr;59(4):762–9.
- Sutherland DJ, McPherson DD, Renton KW, Spencer CA, Montague TJ. The effect of caffeine on cardiac rate, rhythm, and ventricular repolarization. Analysis of 18 normal subjects and 18 patients with primary ventricular dysrhythmia. Chest. 1985 Mar;87(3):319–24.
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