Diagnostic and Prognostic Implications of Exercise Treadmill and Rest First-Pass Radionuclide Angiography in Patients With Pulmonary Hypertension.

Abstract

Pulmonary hypertension (PH) is characterized by abnormally increased pulmonary vascular pressure, leading to deteriorated right ventricular function and premature death. Pulmonary mean transit time (PMTT) and biventricular function response to exercise in first-pass radionuclide angiography (FP-RNA) may provide early detection and timely disease monitoring of PH. This study aimed to investigate the diagnostic and prognostic values of this imaging modality in PH patients. Left and right ventricular ejection fraction (LVEF/RVEF) and PMTT at rest and immediately after exercise treadmill test were measured by FP-RNA in 77 consecutive patients with clinical presentations suggestive of PH (aged 46 ± 15 years, 33 men), mostly with symptoms of unexplained progressive dyspnea. These parameters, along with other clinical variables, were correlated with right-sided heart catheterization data and clinical outcomes. Fifty patients (64.9%) were diagnosed as having definite PH. Besides higher N-terminal pro-B-type natriuretic peptide levels, right atrial pressure, and pulmonary vascular resistance, PH patients had significantly longer PMTT, lower LVEF after exercise and rest, and lower poststress RVEF (all P < 0.05), compared with non-PH subjects. Moreover, PH patients exhibited stress-induced right ventricular dysfunction and stationary poststress PMTT. Poststress PMTT and echocardiography had comparable diagnostic utility (area under the curve, 0.80 vs 0.84, respectively). Eighteen patients died during a median follow-up period of 380 days. Failure of exercise treadmill test, lower peak heart rate response, and stress/rest LVEF ratio of less than 90% using exercise treadmill FP-RNA were independent predictors of mortality in PH patients. Exercise treadmill and rest FP-RNA provided diagnostic value and had prognostic implications in patients with PH.