Background Exercise Doppler echocardiography helps to select patients who need right-sided heart catheterization (RHC) . We introduced a formula for estimating mean pulmonary arterial pressure (mPAP) using it for connective tissue diseases (CTD) patients including systemic sclerosis (SSc) . Additionally, improved detection of pulmonary hypertension (PH) using pulmonary function test (PFT) has also been reported .
Objectives To validate the applicable formula with extended patients for selecting CTD patients with early PH who need RHC based on the results of their exercise Doppler echocardiography and to compare its diagnostic value with a formula using PFT.
Methods A total of 231 CTD patients having either dyspnea or lower carbon monoxide diffusing capacity (DLCO) were performed Doppler echocardiography before/after exercise with the Master's double two-step. RHC was recommended in 68 patients (29%) who had >45mmHg of tricuspid regurgitation pressure gradient (TRPG) just after exercise Doppler echocardiography or who had unexplained dyspnea or <40% of DLCO, and 32 patients (47%) agreed to undergo RHC. We derived a formula estimating mPAP with 32 patients and validated with the additional 25. Using the data from our 32 SSc patients, we also investigated its diagnostic value of a formula for estimating mPAP derived from PFT and SpO2, which was previously reported .
Results The 32 patients for the derivation consisted of 6 (19%) and 5 (16%) with borderline mPAP and manifest PH, respectively. TRPG measured at 3 minutes explained 53% of the variability in the mPAP (r2 =0.5305, P<0.0001), which was higher than TRPG at rest (r2 =0.1860, P=0.0137) or TRPG measured just after the exercise (r2 =0.4673, P<0.0001). The derived formula for estimating mPAP was the following: estimated mPAP =0.551 + 0.384 TRPG (post 3 minutes).
Applying the formula to the validation cohort of 25 patients, which included 3 patients with borderline mPAP and 7 with manifest PH, gave a good correlation between the estimated and actual mPAP (Spearman r =0.6051, p=0.0014). In receiver operating characteristic, the area under the curve was 0.885. Using an estimated threshold of 16.5 mmHg for diagnosis of PH, the sensitivity and specificity were 86% and 78%, respectively. There was no significant correlation of estimated mPAP derived from a formula with PFT and SpO2  with actual mPAP in our 32 SSc patients (Spearman r =0.2262, p=0.2132).
Conclusions The provided formula using exercise Doppler echocardiography for estimating mPAP would help the selection of candidate CTD patients potentially having early PH, whose diagnostic value was higher than that from PFT.
Lindqvist P et al. Echocardiography based estimation of pulmonary vascular resistance in patients with pulmonary hypertension: a simultaneous Doppler echocardiography and cardiac catheterization study. Eur J Echocardiography, 2011; 12: 961.
Yamasaki Y et al. Derivation and validation of a formula for screening and identification of early pulmonary hypertension using exercise Doppler echocardiography in patients with connective tissue diseases. EULAR 2013.
Schreiber B et al. Improving the detection of pulmonary hypertension in systemic sclerosis using pulmonary function tests. Arthritis Rheum, 2011; 63: 3531.
Disclosure of Interest None declared