She had to be rushed to a hospital for an overnight stay after suffering a cardiac arrhythmia during an experiment.

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An autopsy concluded she died of cardiac arrhythmia due to caffeine toxicity.

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Coroner David Crerar said her Coca-Cola consumption had given rise to cardiac arrhythmia, a condition when the heart beats too fast or too slow.

BBC: Coca-Cola bottles (Archive shot)

And although EPA attributed her heart problem to PM2.5 in a published report, no one ever bothered to warn subsequent subjects of cardiac arrhythmia risk.

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Atrial fibrillation is the most common clinically significant cardiac arrhythmia.

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Laurence Epstein, chief of cardiac arrhythmia at Brigham and Women's Hospital in Boston, said that because the true risks of Riata are unclear, he leaves the choice up to his patients.

WSJ: Agonizing Choices for Heart Patients

Vollmer had the symptoms of long Q-T Syndrome, a condition that often leads to heart arrhythmia and sudden cardiac arrest.

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The condition, says Lee, can cause arrhythmia and sudden cardiac death.

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According to Dr. Sana Al-Khatib, lead researcher of the study published Tuesday in the Journal of the American Medical Association, ICDs often are recommended as a primary prevention tactic for patients who are at high risk for a cardiac arrest or life-threatening arrhythmia, but who have not yet suffered from these symptoms.

CNN: STORY HIGHLIGHTS

The new computer simulation allows doctors and physicists to model the faulty heart beats (arrhythmias) that can cause cardiac arrest, and run episodes of arrhythmia time and again, looking for the best way of treating it.

BBC: Virtual heart