QT interval dispersion as a predictor of arrhythmic events in congestive heart failure Importance of aetiology

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Abstract
Aims Identification of patients with congestive heart failure at risk of sudden death remains problematic and few data are available on the prognostic implications of QT dispersion. We sought to assess the predictive value of QT dispersion for arrhythmic events in heart failure secondary to dilated cardiomyopathy or ischaemic heart disease. Methods and Results Twelve-lead ECGs calculated for QT dispersion, 24h Holter ECGs and signal-averaged ECGs were prospectively recorded in 205 heart failure patients in sinus rhythm. The 86 patients with ischaemic heart disease and the 119 with dilated cardiomyopathy were not significantly different as regards NYHA grades (51 vs 49% in grades III–IV), cardiothoracic ratio (57±7 vs 57±6%) and ejection fraction (28±8 vs 29±9%). The mean QT dispersion (66±29 vs 65±27ms), the frequency of non-sustained ventricular tachycardia (37 vs 38%) and ventricular late potentials (41 vs 40%) were not significantly different in patients with ischaemic or dilated cardiomyop-athy. QT dispersion was not significantly related to other arrhythmogenic markers. During follow-up (24±16 months), 66 patients died, 22 of them died suddenly and seven presented a spontaneous sustained ventricular tachycardia. In patients with dilated cardiomyopathy, in multivariate analysis, only a QT dispersion >80ms was an independent predictor of sudden death (RR: 4·9, 95% CI 1·4–16·8,PPConclusion: In congestive heart failure, abnormal QT dispersion can identify patients with dilated cardiomyopathy who are at high risk of arrhythmic events.

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