Six-Minute Walk Stress Echocardiography Found To Predict PH in Connective Tissue Disease
Connective tissue diseases that largely affect bone, cartilage, and fat can sometimes be associated with pulmonary hypertension. Since not all patients with connective tissue disease will eventually develop pulmonary hypertension, it is important to be aware of how pulmonary hypertension can be found in the subset of affected patients. A research team led by, and , at Tokushima University Hospital in Japan recently confirmed that the six-minute walk (6MW) stress echocardiography test is useful in predicting the presence of pulmonary hypertension in connective tissue disease patients.
“This study hypothesized that pulmonary circulation pressure-flow relationships obtained by 6-min walk (6MW) stress echocardiography would better delineate differential progression of pulmonary hypertension and predict development of pulmonary hypertension during follow-up,” wrote Dr. Kusunose, lead author of “Prediction of Future Overt Pulmonary Hypertension by 6-Min Walk Stress Echocardiography in Patients With Connective Tissue Disease,” which was published in Journal of the American College of Cardiology. Pulmonary circulation pressure-flow relationships describe how cardiac output and blood flow are affected by the pressure gradient within the pulmonary artery. More often than not, cardiac output is negatively affected by pulmonary hypertension. This phenomenon is especially evident during exercise.
To investigate if this holds true in patients with connective tissue disease, the research team identified 78 individuals with connective tissue disease and conducted a 6MW stress echocardiographic test. The researchers followed up with the patients yearly for up to five years. During the five-year period, 16 patients were diagnosed with pulmonary hypertension via right heart catheterization, the gold standard for diagnosing pulmonary hypertension.
When making connections between the baseline 6MW stress echocardiographic test, the researchers noted that, “The 6MW stress echocardiography noninvasively provides an incremental prognostic value of pulmonary hypertension development in connective tissue disease.” In other words, patients who exhibited early characteristics of pulmonary hypertension, such as early diastolic tricuspid annulus motion velocity and an altered change in pressure relative to change in flow (ΔmPAP/ΔQ), were highly likely to develop pulmonary hypertension.
The researchers were able to create a prediction model that used ΔmPAP/ΔQ, and their model estimated that a ΔmPAP/ΔQ of more than 3.3 mm Hg/l/min was indicative of future pulmonary hypertension. Clinicians may be able to use this diagnostic criteria when evaluating their connective tissue disease patients for pulmonary hypertension.