Introduction : Patients with heart failure (HF ) with systolic dysfunction of moderate to severe exhibit significant reduction in the ability to exercise compared to those with mild dysfunction , and have worse prognosis. However, some clinical markers of severity and diagnosis widely used in this population such as ejection fraction (EF) , are not always able to translate the actual degree of cardiac damage as well as their relationship with the cardiorespiratory fitness of these individuals and prognosis .

Objective: To evaluate the ability of the global longitudinal strain ( GLS ) in predicting exercise tolerance in heart failure patients with moderate and significant systolic dysfunction.

Inclusion Criteria:

• moderate and significant systolic dysfunction (LVEF < 45%) assessed by transthoracic echocardiography recent ( last month before evaluation ) Teichholz method , or when in the presence of contractile deficit target , by the Simpson method.

Exclusion Criteria:

• deformity in the face to prevent the coupling of the mask to perform the CPET ,
• orthopedic and neurological diseases that could make it impossible to perform the tests ,
• patients with psychiatric disorders that restricted them to respond to the questionnaire ,
• HF FC IV or hospitalization in the last three months ,
• angina unstable;
• myocardial infarction or heart surgery up to three months before the survey ;
• FEV1 / FVC <70 % predicted characterizing obstructive respiratory disorder .

The study population consisted of adults 21-65 years diagnosed with HF of all etiologies , in functional class II and III by the New York Heart Association ( NYHA ) , sedentary , of both sexes.