Exercise limitation associated with asymptomatic left ventricular impairment: analogy with stage B heart failure

Stage B heart failure (SBHF) describes asymptomatic ventricular disease that may presage the development of heart failure (HF) symptoms. This entity has been largely defined by structural changes; the roles of sensitive indicators of nonischemic left ventricular (LV) dysfunction, such as LV strain, are undefined.

This study sought to define the association of exercise capacity with left ventricular hypertrophy (LVH) and systolic/diastolic dysfunction in asymptomatic patients with HF risk factors.

We used echocardiography to study 510 asymptomatic patients (age 58 ± 12 years) with type 2 diabetes mellitus, hypertension, or obesity. The results of cardiopulmonary exercise testing in patients with structural evidence of SBHF were compared with those in patients with subclinical dysfunction, defined by reduced LV strain (>-18%) or increased LV filling pressure (E/e' >13).

Compared with healthy subjects, groups with LV abnormalities differed in terms of oxygen uptake (peak VO2): 25.5 ± 8.2 versus 21.0 ± 8.2 for strain >-18% (p < 0.001); 26.4 ± 8.0 versus 19.0 ± 7.2 for E/e' >13 (p < 0.0001); and 26.0 ± 7.7 versus 15.9 ± 6.9 ml/kg/min for LVH (p < 0.0001). SBHF, defined as ≥1 imaging variable present, was associated with lower peak VO2 (beta = -0.20; p < 0.0001) and metabolic equivalents (beta = -0.21; p < 0.0001), independent of higher body mass index and insulin resistance, older age, male sex, and treatment with beta-blockers.

LVH, elevated LV filling pressure, and abnormal myocardial deformation were independently associated with impaired exercise capacity. Including functional markers may improve identification of SBHF in nonischemic heart disease.