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Background and aim: Heart failure (HF) is a major and growing health problem characterized by high mortality, frequent hospitalization, reduced quality of life and a complex therapeutic regimen. Six minute walking test (6-MWT) may serve as a reproducible test for assessing exercise capacity in HF patients and can be clinically predicted. The aim of this study was to assess clinical, biochemical and echocardiographical predictors of limited exercise capacity in HF patients.

Methods: The study subjects were 135 consecutive clinically stable HF patients (64±11 years, 66 [47%] female, classified as NYHA I-III). Echocardiography, including tissue Doppler measurements, was performed in all patients. A six minute walk test (6-MWT) distance was performed in all patients, who were divided into two groups based on the 6-MWT distance (Group I: ≤ 300 m and Group II: >300 m).

Results: Patients with limited exercise performance (≤ 300 m) were older (p<001), more frequent female (p=0.007) and diabetics (p=0.003), had lower level of hemoglobin (p=0.02), larger left atrium (LA, p=0.003), higher basal heart rate (p=0.009), higher E/e’ ratio (p=0.01) and lower septal systolic myocardial velocity (p=0.03) compared with good performance patients. Enlarged LA [2.856 (1.439-5.666), p=0.003], older age [1.110 (1.036-1.188), p=0.003], increased basal heart rate [1.055 (1.012-1.099), p=0.012] and the presence of diabetes [3.321 (1.022-10.796), p=0.046] independently predicted poor 6-MWT performance.

Conclusions: In patients with HF, the limited exercise capacity assessed by 6-MWT, is related mostly to the enlarged left atrium as e reflection of longstanding increased left ventricular filling pressure, increased basal heart rate, in addition to the older age and the presence of diabetes. These findings highlights the need of the optimal medical treatment of HF patients towards the decreasing LV filling pressure and heart rate.