Improvement of exercise tolerance in cardiopulmonary testing with sustained safety after regular training in outpatients with systolic heart failure (NYHA III) and an implantable cardioverter-defibrillator. Prospective 18-month randomized study

Abstract

Introduction: The aim of the study was to evaluate the impact of individual training on the level of physical capacity and echocardiographic parameters in patients with systolic heart failure (SHF), NYHA III and an implantable cardioverter-defibrillator (ICD).

Material and methods: The study included 84 patients with SHF, randomly assigned to one of two groups: with regular training (ICD-Ex) and a control group (ICD-control). The ICD-Ex group participated in a hospital rehabilitation program which after discharge was individually continued for 6 months in an outpatient setting. The ICD-control group participated in a training program during hospitalization, but after discharge did not perform any controlled activities. Prior to discharge, at 6 and 18 months cardiopulmonary exercise testing (CPX), standard echocardiographic examination and the 6-minute walk test (6-MWT) were performed in all patients.

Results: After 18 months in the ICD-Ex group most of the CPX parameters improved significantly (VO₂ peak, ml/kg/min: 13.0 ±4.1 vs. 15.9 ±6.1, p < 0.0017; VCO₂ peak, l/min: 1.14 ±0.34 vs. 1.58 ±0.65, p < 0.0008; Watt: 74.5 ±29.7 vs. 92.6 ±39.1, p < 0.0006; METs 3.72 ±1.81 vs. 4.35 ±1.46, p < 0.0131). In the ICD-control group no significant improvement of any parameter was observed. Left ventricular systolic dimensions remained significantly lower at 18 months only in the ICD-Ex group (49.5 ±11.0 vs. 43.4 ±10.0, p < 0.011). Left ventricular ejection fraction in both groups significantly increased at 6 and 18 months compared to baseline (ICD-Ex: 25.07 ±5.4 vs. 31.4 ±9.2, p < 0.001, vs. 30.9 ±8.9, p < 0.002, ICD-C: 25.1 ±8.3 vs. 29.2 ±7.7, p < 0.012 vs. 30.1 ±9.1, p < 0.005). Distance of the 6-MWT was significantly improved after 6 and 18 months in the ICD-Ex group and was overall longer than in the ICD-control group (491 ±127 vs. 423 ±114 m, p < 0.04).

Conclusions: An individual, 6-month training program, properly controlled in patients with SHF and an implanted ICD, was safe and resulted in a significant improvement of exercise tolerance and capacity and echocardiographic parameters.

Keywords: implantable cardioverter-defibrillator; systolic heart failure; training programs.

Figure 1

Study design ICD-Ex – rehabilitation group, ICD-control – control group.

Figure 2

Comparison of walking distance in 6-MWT before and after training program (6 months) and after 18-month follow-up ICD-Ex – rehabilitation group, ICD-control – control group, 6-MWT – 6-minute walk test.

Figure 3

NYHA class in study groups (ICD-Ex and ICD-control), evaluated in consecutive control visits ICD-Ex – rehabilitation group, ICD-control – control group.