QTc dispersion and risk of cardiac death in peripheral vascular disease. Three facets of the study need attention.

EDITOR,—Darwood Darbar and colleagues showed the predictive value of QTc dispersion (>/=60 ms) in patients with peripheral vascular disease,1 but we think that three parts of this paper need attention. The first is the patient population. This small, retrospective study was not controlled for risk factors, which introduces significant selection bias. Patients with peripheral arterial disease have a higher incidence of coronary artery disease and its complications. Ischaemic burden (symptomatic or asymptomatic) and the severity of coronary stenosis influences prognosis.2 Mean ejection fraction is useful, but in individual patients the above …