INFLUENCE OF PHYSICAL TRAINING ON T-WAVE ALTERNANS ASSESSED DURING EXERCISE TEST IN HEART FAILURE PATIENTS
How various factors influence T-wave alternans (TWA) is still under discussion. There are no data about the influence of exercise training (ET) on TWA in heart failure (HF) patients (pts). Purpose. To evaluate the influence of ET on TWA assessed during exercise test in HF pts.
Methods: The study group comprised 111 pts (58±11 years) with HF (NYHA class II and III; EF<40%). After three weeks of clinical stability, the pts were randomized to either 8 weeks ET, five times a week, at 40-70% of maximal estimated heart rate - training group, n = 75 (TG), or to a control group, n = 36 (CG). TWA was calculated by the spectral method during exercise test before and after 8 weeks of follow-up.The effectiveness of ET was assessed by changes - delta (Δ) in NYHA class and peak oxygen consumption (pVO2) in cardiopulmonary exercise test as a result of comparing NYHA and pVO2 (ml/kg/min) from the beginning and the end of the program.
Results The groups were comparable in terms of demographic data, baseline clinical parameters and pharmacotherapy. Considering all pts, 57% in TG and 64% in CG were ineligible for TWA assessment due to: atrial fibrillation, pacemaker dependency, physical inability to undertake the exercise test. Eligible for TWA analysis were 32 pts in TG and 13 pts in CG. Changes in TWA In as many as 11 TG pts (34%), TWA results were changed, in contrast to CG with changes in TWA results between the beginning and the end of observation only in 2pts (15%). Despite the fact that in TG we observed lower Kappa value [k=0.4601 95%CI (0.2077-0.7125) p=0.7055] than in CG [k=0.7451 95%CI (0.4395-1) p=0.5724], these changes did not achieve statistical difference. Effectiveness of ET. Cardiac telerehabilitation resulted in a significant improvement in NYHA class (Δ-0.28±0.46, p 0.0015) and pVO2 ( Δ 2.02±2.38, p 0.0001). In CG we did not observe significant changes in these parameters. Between-group analysis showed that the differences between TG and CG were statistically significant: in Δ pVO2 (p=0.0009) and Δ NYHA class (p= 0.0364).There were correlations between the improvement in NYHA class and favorable changes in TWA in TG (r-0.38, p-0.03). We did not observe this effect in CG. There were no correlations between improvement in pVO2 and TWA in either group.
Conclusions: Exercise training seems to influence TWA but further studies on larger groups of pts are necessary. Less than half of patients with HF were eligible for TWA testing.