Very low calorie diets and pre-fasting prolonged QT interval: a hidden potential danger

ABSTRACT

The asssociation 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 the presence of hypocalcaemia or hypokaemia, by the use of psychotropic drugs, and by the presence of intrinsic cardiac disease or bradycardias. Possible less well appreciated is the potiental 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 administration, when severly symptomatic paroxysms of torsade de pointes were recorded. Successful therapy with lignocaine and prompt re-feeding supressed 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 caloric 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 (AU)