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Exercise capacity in patients with beta-thalassemia major: relation to left ventricular and atrial size and function
A Trikas1, K Tentolouris, G Katsimaklis
1Department of Cardiology, University of Athens Medical School, Athens, Greece.
Insights
Exercise capacity in beta-thalassemia major is linked to left atrial function, not left ventricular function. Left atrial size and systolic dysfunction predict reduced exercise capacity in these patients.
Area of Science:
- Cardiology
- Hematology
- Exercise Physiology
Background:
- Echocardiography alone may not fully reflect functional status in beta-thalassemia major patients.
- Peak oxygen uptake (Vo2 max) and anaerobic threshold (AT) are objective measures of exercise capacity.
Purpose of the Study:
- To investigate the relationship between exercise capacity and echocardiographic measures of atrial and ventricular function in beta-thalassemia major.
Main Methods:
- Echocardiography and cardiopulmonary exercise testing were performed on 40 beta-thalassemia major patients and 30 controls.
- Measurements included left atrial and ventricular volumes, left atrial active emptying fraction (ACTEF), left ventricular ejection fraction (LVEF), Vo2 max, and AT.
Main Results:
- Beta-thalassemia patients showed reduced Vo2 max and AT, larger left atrial volume, and lower ACTEF and LVEF compared to controls.
- Vo2 max and AT were inversely related to left atrial maximal volume (Vmax) and directly related to ACTEF in patients.
- Exercise capacity parameters showed weak correlation with LVEF in beta-thalassemia major patients.
Conclusions:
- Exercise capacity in beta-thalassemia major is not correlated with left ventricular dimensions or function.
- Left atrial size and systolic dysfunction are likely predictors of diminished exercise capacity in this population.
Objectives:
The objective of this study was to examine the association between exercise capacity and echocardiographic indexes of atrial and ventricular function and size in patients with beta-thalassemia major.
Background:
In patients with beta-thalassemia major, the assessment of cardiac function with echocardiography alone does not always correspond to their functional status. Peak oxygen uptake and anaerobic threshold, on the other hand, constitute 2 objective and reproducible determinants of exercise capacity in patients with heart failure.
Methods And Results:
Forty consecutive patients (22 women and 18 men, 18 to 30 years old) who were in stable condition while receiving regular transfusions and 30 age- and sex-matched control subjects were studied. At 2 to 3 days after the last transfusion, each subject underwent complete echocardiographic study followed by cardiopulmonary exercise testing. Left atrial volumes (maximal [Vmax], at onset of atrial systolic [Vp], and minimal [Vmin]) and left ventricular volumes were measured with the biplane area-length method, and left atrial active emptying fraction (ACTEF) and left ventricular ejection (LVEF) fraction were calculated. Peak oxygen uptake (Vo 2 max) and anaerobic threshold (AT) were also estimated. After transfusion, patients with beta-thalassemia major had reduced Vo 2 max and AT and greater left atrial volume in comparison with control subjects. Also, ACTEF and LVEF were significantly lower in the patient group. Moreover, Vo2 max and AT were inversely related to Vmax (r = -0.74 and r = -0.80, respectively) and directly related to ACTEF (r = 0.85 and r = 0.82, respectively) in beta-thalassemia major, whereas they were poorly related to LVEF (r = 0.50 and r = 0. 53, respectively). In the control group, Vo 2 max and AT parameters were related to Vmax and ACTEF in a similar way to that in the beta-thalassemia group.
Conclusions:
In patients with beta-thalassemia major, exercise capacity does not correlate with left ventricular dimensions and function. On the contrary, left atrial size and systolic dysfunction are probably predictors of decreased exercise capacity.