Many physicians will tell patients to avoid caffeine as it is thought to lead to arrhythmias, however evidence does not support this practice.
Animal studies show high doses of caffeine produces catecholamine triggered activity
Small studies in high risk patients (recent MI, malignant arrhythmias) have shown no increase in frequency or severity of arrhythmia
No large scale human studies exist evaluating caffeine's effects on patients with malignant arrhythmias (VF/VT)
Overall, the data suggest that caffeine is well tolerated in moderate doses in most patients, even those with known or suspected arrhythmias
In patients who claim sensitivity to caffeine, or in those with known arrhythmias where catecholamines are felt to drive the arrhythmia, caffeine may be discouraged by physicians.
References
Pelchovitz DJ, GoldbergerJJ. Arrhythmias: A Review of the Evidence. AJM April 2011;124(4):284-9.
