[QT interval dispersion in hospital patients admitted with cardiac insufficiency. Determinants and prognostic value]

The determinants and the prognostic value of the QT interval dispersion are analysed in a group of consecutive patients admitted to hospital with heart failure.

One hundred twenty-two consecutive patients admitted because of heart failure in whom a reliable measurement of QT dispersion in the first electrocardiogram was obtained (maximum QT-minimum QT) were studied. The main clinical, analytic and echocardiographic data were recorded. A control group (n = 35) matched in age and sex with the study group was also analysed.

The study group showed a greater QT dispersion than the control group (62 +/- 30 vs 40 +/- 21 ms; p = 0.01). Those cases with a QT dispersion > 80 ms (n = 50; 41%) exhibited a lower natremia (138 +/- 6 vs 141 +/- 4 mEq/l; p = 0.01), a higher probability of ischemic aetiology (52 vs 33%; RR = 2.2; IC95% 1.05-4.7; p = 0.04), an increased mortality during the first year (20 vs 6%; RR = 4.7; IC95% 1.3-16; p = 0.01) and during the whole follow-up (38 vs 19%; RR = 3.4; IC95% 1.3 a 8.6; p = 0.01) than those patients with a QT dispersion < 80 (n = 72; 59%). There were no significant differences between both groups with regard to the clinical, analytic or echocardiographic data. In the multivariate analysis only the ischemic etiology (p = 0.002) and the NYHA grade (p = 0.02) were related to a greater mortality.

Patients with heart failure show an increased QT interval dispersion. This parameter is a simple tool that suggests an ischemic etiology and can help in prognosis stratification.