QT dispersion has no prognostic value in patients with symptomatic heart failure: an ELITE II substudy.
This study prospectively investigated 3,118 standard 12-lead ECGs recorded in 1,804 patients, who participated in the Losartan Heart Failure Survival Study--ELITE II clinical trial. After exclusion of patients with rhythms other than sinus, or atrioventricular block, or poor quality ECGs, 986 (703 men, mean age 71 +/- 7 years) with baseline ECGs were retained, of whom 615 patients had follow-up ECGs 4 months after randomization. QT intervals were manually measured with a digitizing board. Heart rate, QRS duration, maximum QT and JT intervals, QT and JT dispersion (the interval ranges across all measurable ECG leads) were analyzed. In the overall population, there were 140 (14%) deaths from all causes, including 119 (12%) cardiac and 59 (6%) sudden deaths during a follow-up of 540 +/- 153 days. The mean heart rate was significantly faster in nonsurvivors than in survivors (77 +/- 16 vs 74 +/- 14 beats/min, P = 0.006), and in patients who died of cardiac death (76 +/- 16 beats/min, P = 0.04 vs survivors). Mean QRS duration was significantly longer in nonsurvivors (107 +/- 25 ms), and in the subgroups who died of cardiac (107 +/- 24 ms) or sudden death (112 +/- 23 ms) than in survivors (99 +/- 24 ms, P < 0.01 for all). The maximum and corrected (QTc) QT intervals were similar for nonsurvivors, regardless of cause of death, and in survivors (P = NS for all comparisons). Significantly shorter maximum and corrected (JTc) JT intervals were observed in victims of any mode of death compared to survivors (P < 0.05 for all). There was no significant difference in QT or JT dispersion between patients with any mode of death and survivors (P > 0.1 for all). Neither losartan nor captopril significantly modified QT or JT dispersion. In conclusion, increased QT dispersion is not associated with increased mortality in patients with heart failure, and is not suitable to examine drug efficacy in these patients.