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High-dose caffeine and cardiac rate and rhythm in normal subjects
P F Newcombe1, K W Renton, P M Rautaharju
1Department of Medicine, Dalhousie University, Halifax, Nova Scotia, Canada.
Insights
High-dose caffeine intake did not significantly alter cardiac rhythm or rate in healthy adults. This study found no clinically significant ventricular or supraventricular dysrhythmias associated with caffeine consumption in normal subjects.
Area of Science:
- Cardiology
- Pharmacology
- Electrophysiology
Background:
- Previous studies indicated a potential link between moderate caffeine doses and increased ventricular ectopic beats (VEBs) in patients with pre-existing dysrhythmias.
- A prior study showed a statistically insignificant increase in VEBs in normal subjects, raising concerns about beta-error and necessitating further investigation.
Purpose of the Study:
- To investigate the electrophysiologic effects of high-dose caffeine on cardiac rhythm and rate in healthy adults.
- To determine if elevated caffeine consumption induces clinically significant ventricular or supraventricular dysrhythmias in a normal population.
Main Methods:
- Recruited 34 healthy adults (15 males, 19 females; mean age 31 years) who abstained from caffeine for 72 hours.
- Calculated individual caffeine half-life and administered caffeine at 1 mg/kg every 0.5 half-life during waking hours.
- Utilized 24-hour Holter ECG monitoring before and during caffeine administration to assess cardiac rhythm and dysrhythmias.
Main Results:
- High-dose caffeine administration did not result in significant changes in prevailing cardiac rhythm or rate in normal adults.
- No clinically significant ventricular or supraventricular dysrhythmias were observed in the study participants following caffeine ingestion.
Conclusions:
- In healthy adults, high-dose caffeine consumption does not appear to adversely affect cardiac rhythm or rate.
- Caffeine, even at high doses, does not induce clinically significant cardiac dysrhythmias in individuals without pre-existing cardiac conditions.
Abstract:
In a previous 24-hour study of the electrophysiologic effects of moderate dose caffeine (1 mg/kg body weight/half-life), we found a significant (p less than 0.01) increase in ventricular ectopic beat (VEB) frequency among 18 patients with preexisting primary ventricular dysrhythm (mean 207 +/- 350 VEBs/hour, no caffeine, versus 307 +/- 414 VEBs/hour, caffeine). We also found a statistically insignificant (NS) increase in the incidence of infrequent VEBs in 18 normal control subjects (four of 18, no caffeine vs nine of 18 caffeine). Because of the high risk of beta-error among the previously-studied normal control subjects, we tested another group of 34 normal subjects, 15 males and 19 females with a mean age of 31 years (range 21 to 49 years), using a higher dose of caffeine. All subjects abstained from caffeine for 72 hours and had a control 24-hour Holter ECG recorded between hours 48 and 72. Caffeine half-life was calculated for each subject and caffeine was then ingested at 1 mg/kg every 0.5 half-life during all waking hours. A 24-hour Holter test was recorded, beginning just prior to the second caffeine dose. It was concluded that in normal adults, even high-dose caffeine does not affect prevailing cardiac rhythm and rate, and moreover, does not cause clinically significant ventricular or supraventricular dysrhythm.