CARDIOVASCULAR MEDICINE

Long QTc predicts future cardiac death in stroke survivors

K Y K Wong¹, R S Mac Walter², D Douglas², H W Fraser², S A Ogston³, A D Struthers¹

¹ The Cardiovascular Research Group, Department of Clinical Pharmacology and Therapeutics, University of Dundee Medical School, Ninewells Hospital, Dundee, UK
² Stroke Studies Centre, Department of Medicine, University of Dundee Medical School
³ Department of Epidemiology and Public Health, University of Dundee Medical School

Correspondence to:
Correspondence to:
Dr Kenneth Wong, Departments of Clinical Pharmacology and Therapeutics, University of Dundee Medical School, Ninewells Hospital, Dundee DD1 9SY, UK;
kywong{at}doctors.org.uk

Objectives: To test the hypothesis that the QTc of any lead of the ECG predicts death after stroke, and to determine which lead of the ECG carries the greatest risk of cardiac death when its QTc is measured.

Design: Standard 12 lead ECGs were analysed by one observer who was blind to patient outcome.

Setting: A major teaching hospital in Scotland.

Patients: 404 stroke survivors were studied at approximately one year after the cerebrovascular event and followed for up to 6.3 years.

Outcome measures: Death from any cause and cardiac mortality.

Results: The QTc measured from any lead of the ECG (except aVR) was associated with death from any cause. A prolonged QTc in limb lead III and chest lead V6 carried the highest relative risk of cardiac death (a 3.1-fold incease). After adjusting for overt ischaemic heart disease, pulse pressure, glucose, and cholesterol, a prolonged QTc in lead V6 was associated with a relative risk of cardiac death of 2.8 (95% confidence interval (CI) 1.1 to 7.3) (p = 0.028) and of death from all causes of 2.9 (95% CI 1.6 to 5.3) (p < 0.001). If the QTc in V6 exceeded 480 ms, then the specificity of predicting cardiac death within five years after the stroke was 94%.

Conclusions: Although treatment of the conventional modifiable risk factors is important, stroke survivors with a prolonged QTc in lead V6 are still at a high risk of cardiac death and may need more intensive investigations and treatments than are currently routine practice.

Keywords: cardiac death; QTc; stroke; hypertension

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