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A detailed history of patients with arrhythmia or syncope might need to include their cola intake or the origin of the honey they consume, two case studies suggest.

One case involved a 31-year-0ld woman who was admitted with traumatic syncope. There was no family history of sudden death and a physical exam was normal, according to Naima Zarqane, MD, and colleagues from The Princess Grace Hospital Centre, in Monaco.

The patient's ECG showed prolonged QTc (610 ms) and blood tests revealed severe potassium loss (2.4 mmol/L), they reported at the EUROPACE 2013 meeting in Athens.

Normal blood potassium levels range between 3.5 to 5.1 mmol/L and normal QTc for women is 450 ms or less.

Clinicians also excluded digestive symptoms, intake of licorice, and metabolic or hormonal abnormalities.

However, the patient admitted she had had no water since the age of 15. Instead, she drank only cola beverages, about 2 liters per day, the researchers reported.

She was weaned off cola, "without oral potassium supplements," and at the end of a week, her potassium returned to 4.1 mmol/L and 4.2 mmol/L at one month. Also, at 1 week, her QTc decreased to normal (430 ms).

"Pathways of cola-induced hypokalemia include potassium wasting via an osmotic diarrhea (due to indigestible high-fructose corn syrup) and osmotic diuresis (due to large glucose load)," Zarqane and colleagues explained.

They also found six other case studies in the literature chronicling too much cola with adverse medical conditions such as rhabdomyolysis, arrhythmias, and even one death related to Torsades de pointes, they reported.

The second case involved a father and son admitted to the emergency room of the Central Hospital in Izmir, Turkey.

The men, ages 68 and 27, were vomiting and complained of dizziness.

The ECGs revealed both patients had a complete atrioventricular block and atrial flutter with slow ventricular response.

A detailed family history revealed they had ingested high amounts of honey from the Black Sea region of Turkey. Turk and colleagues immediately suspected "mad honey poisoning."

Mad honey poisoning occurs after people consume honey contaminated with grayanotoxin, a chemical contained in nectar from the Rhododendron species ponticum and luteum, the researchers noted.

Grayanotoxin is a neurotoxin that binds to the sodium channels in the cell membrane, maintaining them in an open state and prolonging depolarization.

"It's like the effect of cholinergic agents, and results in stimulation of the unmyelinated afferent cardiac branches of the vagus nerve which leads to a tonic inhibition of central vasomotor centers with a reduced sympathetic output and a reduced peripheral vascular resistance," Turk said in a statement.

"This in turn triggers the cardioinhibitory Bezold-Jarisch reflex, which leads to bradycardia, continued hypotension, and peripheral vasodilatation," he added.

When the poisoning is mild, symptoms might include dizziness, weakness, nausea, vomiting, excessive perspiration, hypersalivation, and paresthesia.

Symptoms are generally gone within 24 hours, and can be treated with atropine, saline infusion, and close observation of vital signs for 12-24 hours, they said.

Symptoms of the more severe form of mad honey poisoning include syncope, seizures, complete atrioventricular block, and even fatal tachyarrhythmias (resulting from oscillatory after potentials).

Treatment can include temporary pacemaker implantation and vasopressor agents.

The father and son were discharged from the hospital on the fourth day, without the need for any medications.

An analysis of the honey they had eaten revealed it contained pollen from the Rhododendron species.

"The dissemination of honey around the world means that physicians anywhere may be faced with honey poisoning," Turk said.

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