Semi-quantitative assessment of pulmonary arterial hypertension associated with congenital heart disease through myocardial perfusion imaging.

OBJECTIVE The study aimed to use myocardial perfusion imaging (MPI) as a semi-quantitative method to assess the clinical severity of pulmonary arterial hypertension (PAH) in patients with congenital heart disease (CHD). SUBJECTS AND METHODS A total of 24 patients with PAH related to CHD (PAH-CHD) who received interventional or medical treatment were included. All patients underwent physical examination, cardiac function evaluation, biochemical test, echocardiography, right heart catheterization (RHC), and MPI with 99mTc-methoxyisobutyl isonitrile (99mTc-MIBI) pre and 6 months post treatments. The correlation between MPI target/background (T/B) ratios and other variables were calculated. The receiver operating characteristic (ROC) curves were developed to evaluate the diagnostic value of T/B ratios. RESULTS Most of the cardiac functional parameters, surplus pulse O2 (SPO2), biochemical values and right heart catheterization parameters were found significantly elevated after treatment (P<0.05). Pre-treatment MPI showed that T/B ratio had strong correlations with SPO2, Borg scale, cardiac output (CO), cardiac index (CI), right ventricular stroke volume (RV-SV), pulmonary artery pressure (PAP), total pulmonary resistance (TPR), total pulmonary resistance index (TPRI), pulmonary vascular resistance (PVR), and pulmonary vascular resistance index (PVRI). After 6 months treatment, the correlation between T/B ratios and most of these parameters measured were reduced. Receiver operating characteristics curves showed that the diagnostic performance of MPI T/B ratio in moderate/severe PAH patients was significant. The area under the curve (AUC) when measured pre-treatment was 0.929 (P=0.002) and reduced to 0.800 (P=0.046) at post-treatment. CONCLUSION Semi-quantitative MPI has high diagnostic value in evaluating the severity level of pulmonary arterial hypertension in patients with congenital heart disease. The diagnostic performance of MPI at pre-treatment patients was superior to that at post-treatment. More cases need to be included for further study.