Abstract
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Objectives The right ventricular function response to exercise may early detect pulmonary arterial hypertension (PAH). We aimed to investigate whether rest and stress cardiac function measured using first-pass radionuclide angiography (FP-RNA) is correlated with disease severity in patients with PAH.
Methods Left and right ventricular ejection fraction (LV/RV EF) at rest and immediately after exercise treadmill test (ETT) were measured by FP-RNA in symptomatic 29 patients (43±14 y, 10 man) with suspected PAH Aug 2009, together with other clinical variables including plasma levels of NT-pro-BNP, 6-minute walk test, chest CT, echocardiography and right heart catheterization hemodynamic values were correlated.
Results The PAH diagnosis was confirmed in 19 patients, whose clinical status and hemodynamics were compared with those without PAH (10 patients). In PAH patients, increase of NT-pro-BNP levels, right ventricular pressure, pulmonary vascular resistance (PVR) index, tricuspid regurgitation pressure gradient, dilated right heart and pulmonary trunk size, but lower cardiac output were noted (all P<.05). Two PAH patients failed to complete ETT due to severe sickness. The rest RVEF, rest and post-stress LVEF were not different between two groups; but significantly lower RVEF after ETT was noted in PAH patients. PVR index was the only independent predictor of post-stress RVEF (r=-0.56, P=0.001). Four PAH patients, but none of non-PAH subjects, died during a mean follow-up period of 12.5±10.9 (1-41) months, 3 experienced a deterioration of >5% of RVEF after ETT, and one was too weak to complete ETT, despite all preserved rest RVEF (>35%).
Conclusions Assessment of rest and stress cardiac function by FP-RNA is clinically feasible, but only post-stress RVEF is significantly associated with the disease severity in patients with PAH.
Research Support This work is partly supported by the National Science Council of Taiwan under Grant (NSC 100-2314-B-002-158).