Clinical value of noninvasive pulmonary artery systolic pressure estimates in our patients with pulmonary artery hypertension

Introduction

Invasive and noninvasive measurements of pulmonary artery pressures are used to diagnose and control patients with pulmonary artery hypertension (PAH) [1–3]. In our hospital all patients with PAH are diagnosed and first treated in the ICU. Besides right heart catheterization (RHC), noninvasive estimate of pulmonary artery systolic pressure (PASP) with transthoracic echocardiography (TTE) is performed. As RHC is an invasive procedure it is not suitable to repeat it. We compared values of invasively and noninvasively measured PASP to examine correlation so we could use TTE for ambulatory control and estimation of treatment success in our patients.

Methods

In a retrospective manner we examined the correlation between pulmonary artery pressures estimated by TTE versus RHC among our patients, diagnosed for PAH from 2003 to 2007. The data were collected from 36 patients with PAH of different cause (chronic pulmonary thromboembolism, 12 patients; connective tissue disease, 10 patients; idiopathic pulmonary artery hypertension, eight patients; other, six patients). Bivariate correlations were used for statistical analysis.

Results

The median time interval between methods was 2 (1 to 30) days. The median PASP by RHC was 74.8 (30 to 122) mmHg and by TTE was 62.3 (41 to 110) mmHg (r = 0.65, P < 0.0001). In 29 (80.6%) patients the difference between the two methods was >20 mmHg, and in 10 (27.8%) patients it was <10 mmHg. We did not find a difference between the two methods regarding the cause of PAH.

Conclusion

In our group of patients we found a week correlation between invasively and noninvasively estimated PASP. However, there has been a trend of good correlation for a small proportion of our patients. We conclude that when the first measurements by TTE and RHC correlate well we can use TTE for future evaluation of disease progress and treatment response. When the measurements of the two methods differ we have to exclude potential reversible cause (different examiner, different conditions, to wide time interval) and serial invasive measurements may be needed.