Eli Lilly, for example, a major pharmaceutical company, invested an enormous amount in a drug as a potential solution, but had to terminate it in Phase 3 trials because the medication worsened the patient rather than improved the condition.

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This is a new feature, available on some defibrillator-like devices that are now on the market, which is aimed at people with a form of heart condition that causes their two ventricles to beat slightly out of phase with each other.

ECONOMIST: Case history

This is a potentially deadly condition in which the individual chambers of a heart beat out of phase with each other.

ECONOMIST: Model behaviour