Table 2. Physiological Risk Factors for QTc Prolongation and Arrhythmia.

Cardiac

Long QT syndrome

Bradycardia

Ischaemic heart disease

Myocarditis

MI

Left ventricular hypertrophy

Metabolic

Hypokalemia

Hypomagnesaemia

Hypocalcaemia

Others

Extreme physical exertion

Extreme physical exertion

Anorexia nervosa

Extremes of age – children and elderly may be more susceptible to QT changes

Stress or shock

Female sex

Note: Hypokalemia-related QTc prolongation is more commonly observed in acute psychotic admissions. Also, there are a number of physical and genetic factors which may not be discovered on routine examination, but which probably predispose patients to arrhythmia. Source: The Maudsley Prescribing Guidelines in Psychiatry.[1] Reproduced with permission from Wiley Blackwell.