Acute caffeine poisoning resulting in atrial fibrillation after guarana extract overdose.

UNLABELLED: Guarana (Paullinia cupana) is the climbing vine native to Amazon Basin, characterized by high caffeine content in its seeds. Guarana extract is a common ingredient of energy drinks used in order to boost energy and physical endurance and increase alertness. Severe caffeine intoxication is rare, but may be life-threatening mostly due to supraventricular and ventricular dysrhythmias.

OBJECTIVES: We present the case of intentional caffeine poisoning after ingestion of tablets containing guarana extract, complicated by atrial fibrillation.

CASE REPORT: A44-year-old man with no significant medical history was admitted to hospital about 21 h after ingestion of guarana extract containing 1.6 g of caffeine. Typical symptoms of caffeine toxicity, i.e. nausea, vomiting, anxiety and palpitaions, occurred shortly after ingestion. On admission, he was conscious, with blood pressure of 136/86 mmHg, heart rate of 106-113 beats per minute, fever of 37.8 °C, and symmetrically increased deep tendon reflexes. QTc interval in electrocardiogram was prolonged to 0.542 s. Laboratory tests revealed hypokalemia, hyperglycemia, leukocytosis, as well as elevated creatinine and creatine phosphokinase levels. Approximately 45 h post ingestion, the patient developed atrial fibrillation with fast ventricular rhythm. Tachydysrythmia subsided after infusion of amiodarone and restoration of electrolyte balance. Echocardiogram revealed presence of asymmetrical hypertrophy of the left ventricle with the systolic anterior motion of the mitral valve and normal left ventricular outflow tract gradient suggesting non-obstructive hypertrophic cardiomyopathy.

CONCLUSION: Acute caffeine poisoning may result in atrial fibrillation, especially in predisposed patients with underlying hypertrophic cardiomyopathy.