Influence of aging and chronic heart failure on temporal dispersion of myocardial repolarization

Gianfranco Piccirillo,1 Federica Moscucci,1 Matteo Pascucci,1 Maria Antonella Pappadà,1 Gaetana D’Alessandro,1 Pietro Rossi,2 Raffaele Quaglione,1 Daniele Di Barba,1 Francesco Barillà,1 Damiano Magrì3 1Department of Cardiovascular, Respiratory, Nephrological and Geriatric Sciences, Policlinico Umberto I, “Sapienza” University of Rome, Rome, Italy; 2Division of Cardiology, S. Giovanni Calabita Fatebenefratelli Hospital, Rome, Italy; 3Department of Clinical and Molecular Medicine, Sant’Andrea Hospital, “Sapienza” University of Rome, Rome, Italy Background and purpose: QT and Tpeak-Tend (Te) intervals are associated with sudden cardiac death in patients with chronic heart failure (CHF). We studied age-dependent influence on short-term temporal dispersion of these two variables in patients with postischemic CHF. Method: We grouped 75 CHF and 53 healthy control subjects into three age subsets: ≤50 years, >50 years and ≤65 years, and >65 years. We then calculated the following indices: QT and Te variability index (QTVI and TeVI), the ratio between the short-term variability (STV) of QT or Te, and the STV of resting rate (RR) (QT/RR STV and Te/RR STV). Results: In all different age subgroups, patients with CHF showed a higher level of QTVI than age-matched control subjects (≤50 years: P < 0.0001; >50 years and ≤65 years: P < 0.05; >65 years: P < 0.05). Patients with CHF < 50 years old also had all repolarization variability indices higher than normal age-matched controls (TeVI, P < 0.05; QT/RR STV, P < 0.05; Te/RR STV, P < 0.05), whereas we did not find any difference between the two older classes of subjects. Both QTVI (r2: 0.178, P < 0.05) and TeVI (r2: 0.433, P < 0.001) were positively related to age in normal subjects, even if the first correlation was weaker than the second one. Conclusion: Our data showed that QTVI could be used in all ages to evaluate repolarization temporal liability, whereas the other indices are deeply influenced by age. Probably, the age-dependent increase in QTVI was more influenced by a reduction of RR variability reported in older normal subjects. Keywords: aging, QT variability, heart rate variability, chronic heart failure, sudden death