Background and Rationale:

Individuals with heart failure have severely reduced exercise tolerance and often poor quality of life. Previous studies have reported that both peak oxygen uptake (VO_2peak) and ventilatory efficiency are reliable predictors of prognosis in heart failure patients. However, a considerable degree of uncertainty remains whether the acute exercise responses and quality of life are similar in patients with different heart failure etiologies.

Objective:

The aim of this study was to compare VO_2peak, ventilatory efficiency, quality of life, muscle strength, and metabolic profile in patients with ischemic (IHF) and non-ischemic heart failure (NIHF).

Methods:

We recruited 31 individuals with heart failure (IHF: n = 15, age (mean +/- SD): 67.7 +/- 7.5; NIHF: n = 16, age: 55.1 +/- 12.4). VO_2peak and ventilatory efficiency were obtained during a symptom-limited cycle exercise test. Ventilatory efficiency was measured as the slope of minute ventilation versus carbon dioxide values below the onset of anaerobic threshold (V_E/VCO_2slope). Quality of life was assessed using Minnesota Living with Heart Failure questionnaire. Upper and lower extremity muscle strength was assessed using a 1-repetition maximum procedure on chest press and leg extension exercises, respectively. Fasting blood glucose and lipoprotein profiles were measured using standard laboratory procedures.

Results:

IHF patients were significantly older than NIHF patients (P = .002). Moreover, IHF patients had lower VO_2peak (IHF: 12.7 +/- 4.2 vs. NIHF: 18.0 +/- 5.3 ml/kg/min; P = .005), higher V_E/VCO_2slope (IHF: 37.3 +/- 12.1 vs. NIHF: 28.3 +/- 3.6; P = .013) and a lower quality of life (total score, IHF: 54.3 +/- 15.6 vs. NIHF: 36.4 +/- 18.8; P = .007; physical component, IHF: 24.9 +/- 8.3 vs. NIHF: 16.4 +/- 8.8; P = .009) compared to individuals with NIHF. Differences in VO_2peak, V_E/VCO_2slope, and quality of life remained significant after adjusting for age. IHF and NIHF patients were similar with respect to upper and lower body muscle strength, fasting glucose, and lipoprotein profile (total cholesterol, LDL cholesterol, HDL cholesterol, triglycerides, and total cholesterol to HDL cholesterol ratio).

Conclusions:

Individuals with IHF have lower VO_2peak, higher V_E/VCO_2slope, and reduced quality of life compared to individuals with NIHF. These differences could not be explained by differences in age, muscle strength, or metabolic profile. Future studies need to determine if these subgroups of heart failure patients respond differently to cardiac (exercise) rehabilitation.

Section Description

For more information, contact Marilyn Thomas (204) 488-5854