The association of
torsade de pointes and a prolonged electrocardiographic QT interval is well described. A prolonged QT interval may be congenital or acquired in several ways--by the use of
anti-arrhythmic agents exemplified by
quinidine, by the presence of hypocalcaemia or hypokalaemia, by the use of
psychotropic drugs, and by the presence of intrinsic
cardiac disease or
bradycardias. Possibly less well appreciated is the potential for drastic
weight loss to prolong the QT interval, as the present case report illustrates. A young woman weighing 244 pounds lost 24 pounds in two weeks with a consequent prolongation of QTc interval from pre-diet value of 0.57 seconds to 0.72 seconds at admission, when severely symptomatic paroxysms of
torsade de pointes were recorded. Successful therapy with
lignocaine and prompt re-feeding suppressed the
arrhythmia and, three days later, the QTc was reduced to almost its pre-diet state. A (UK)
DHSS report offers guidelines in the use of very
low calorie diets. This case suggests that a pre-diet electrocardiogram should be carefully assessed for QT prolongation before initiation of dieting to achieve serious
weight loss.